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Shinrin-Yoku (Forest Bathing) and Nature Therapy: A State-of-the-Art Review

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Background: Current literature supports the comprehensive health benefits of exposure to nature and green environments on human systems. The aim of this state-of-the-art review is to elucidate empirical research conducted on the physiological and psychological effects of Shinrin-Yoku (or Forest Bathing) in transcontinental Japan and China. Furthermore, we aim to encourage healthcare professionals to conduct longitudinal research in Western cultures regarding the clinically therapeutic effects of Shinrin-Yoku and, for healthcare providers/students to consider practicing Shinrin-Yoku to decrease undue stress and potential burnout. Methods: A thorough review was conducted to identify research published with an initial open date range and then narrowing the collection to include papers published from 2007 to 2017. Electronic databases (PubMed, PubMed Central, CINAHL, PsycINFO and Scopus) and snowball references were used to cull papers that evaluated the use of Shinrin-Yoku for various populations in diverse settings. Results: From the 127 papers initially culled using the Boolean phrases: "Shinrin-yoku" AND/OR "forest bathing" AND/OR "nature therapy", 64 studies met the inclusion criteria and were included in this summary review and then divided into "physiological," "psychological," "sensory metrics" and "frameworks" sub-groups. Conclusions: Human health benefits associated with the immersion in nature continue to be currently researched. Longitudinal research, conducted worldwide, is needed to produce new evidence of the relationships associated with Shinrin-Yoku and clinical therapeutic effects. Nature therapy as a health-promotion method and potential universal health model is implicated for the reduction of reported modern-day "stress-state" and "technostress.".
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Int. J. Environ. Res. Public Health 2017, 14, 851; doi:10.3390/ijerph14080851 www.mdpi.com/journal/ijerph
Review
Shinrin-Yoku (Forest Bathing) and Nature Therapy:
A State-of-the-Art Review
Margaret M. Hansen *, Reo Jones and Kirsten Tocchini
School of Nursing and Health Professions, University of San Francisco, 2130 Fulton Street, San Francisco,
CA 94901, USA; rjjones2@usfca.edu (R.J.); kntocchini@usfca.edu (K.T.)
* Correspondence: mhansen@usfca.edu; Tel.: +1-014153787577
Academic Editors: Yoshifumi Miyazaki, Hiromitsu Kobayashi, Sin-Ae Park and Chorong Song
Received: 11 June 2017; Accepted: 21 July 2017; Published: 28 July 2017
Abstract: Background: Current literature supports the comprehensive health benefits of exposure
to nature and green environments on human systems. The aim of this state-of-the-art review is to
elucidate empirical research conducted on the physiological and psychological effects of Shinrin-
Yoku (or Forest Bathing) in transcontinental Japan and China. Furthermore, we aim to encourage
healthcare professionals to conduct longitudinal research in Western cultures regarding the
clinically therapeutic effects of Shinrin-Yoku and, for healthcare providers/students to consider
practicing Shinrin-Yoku to decrease undue stress and potential burnout. Methods: A thorough
review was conducted to identify research published with an initial open date range and then
narrowing the collection to include papers published from 2007 to 2017. Electronic databases
(PubMed, PubMed Central, CINAHL, PsycINFO and Scopus) and snowball references were used
to cull papers that evaluated the use of Shinrin-Yoku for various populations in diverse settings.
Results: From the 127 papers initially culled using the Boolean phrases: “Shinrin-yoku” AND/OR
“forest bathing” AND/OR “nature therapy”, 64 studies met the inclusion criteria and were included
in this summary review and then divided into “physiological,” “psychological,” “sensory metrics”
and “frameworks” sub-groups. Conclusions: Human health benefits associated with the immersion
in nature continue to be currently researched. Longitudinal research, conducted worldwide, is
needed to produce new evidence of the relationships associated with Shinrin-Yoku and clinical
therapeutic effects. Nature therapy as a health-promotion method and potential universal health
model is implicated for the reduction of reported modern-day “stress-state” and “technostress.”.
Keywords: Shinrin-Yoku; forest bathing; nature therapy; integrative medicine
1. Introduction
Research conducted in transcontinental Japan and China points to a plethora of positive health
benefits for the human physiological and psychological systems associated with the practice of
Shinrin-Yoku (SY), also known as Forest Bathing FB (FB) [1–3]. SY is a traditional Japanese practice
of immersing oneself in nature by mindfully using all five senses. During the 1980s, SY surfaced in
Japan as a pivotal part of preventive health care and healing in Japanese medicine [4]. The reported
research findings associated with the healing components of SY specifically hones in on the
therapeutic effects on: (1) the immune system function (increase in natural killer cells/cancer
prevention); (2) cardiovascular system (hypertension/coronary artery disease); (3) the respiratory
system (allergies and respiratory disease); (4) depression and anxiety (mood disorders and stress);
(5) mental relaxation (Attention Deficit/Hyperactivity Disorder) and; (6) human feelings of “awe”
(increase in gratitude and selflessness) [5]. Moreover, various contemporary hypotheses, such as:
Kaplan’s Attention Restorative Hypothesis [6]; Ulrich’s Stress Reduction Hypothesis [7]; and Kellert
Int. J. Environ. Res. Public Health 2017, 14, 851 2 of 37
and Wilson’s Biophilia Hypothesis [8] provide support and a lens for the practice of SY and other
forms of nature engagement.
Furthermore, SY may be considered a form of Nature Therapy (NT). Song, Ikei and Miyazaki’s
present day model: Concept of Nature Therapy (CNT) [9] clearly defines NT as “a set of practices
aimed at achieving ‘preventive medical effects’ through exposure to natural stimuli that render a
state of physiological relaxation and boost the weakened immune functions to prevent diseases” [9].
The conceptual model of NT starts with a “stressed state” at the top and then points to the “restorative
effects” of nature (forests, flowers, etc.) where there is a hypothesis of improvement in “physiological
relaxation” and “immune function recovery” responses (individual differences noted). These
responses to nature are then incorporated in the Evidence Based Medicine (EBM) model and is
illustrated by an arrow leading to the “preventive medical effect.” This clear model supports Song,
Ikei and Miyazaki’s [9] review of some medically proven outcomes. Kaplan and Kaplan [6] associated
with exposure to naturally occurring stimuli (all 5 senses) that has a direct effect on increasing the
parasympathetic nervous system and a heightened awareness that leads to a state of relaxation
(Figure 1).
Figure 1. Concept of nature therapy [9]. Permission to publish from Yoshifumi Miyasaki.
Individuals living and interacting in green spaces (GS) report being more energetic, in good
overall health and, have more of a sense of meaningful purpose in life [10]. Current scientific findings
are illuminating what humans intuitively know: nature has great benefits for the human brain and
this is shown through increased happiness, health/well-being and cognition [5]. Historically
speaking, Cyrus the Great intuitively built lush green gardens in the crowded urban capital of Persia
2500 years ago to increase human health and promote a sense of “calm” in a busy city. The 16th
Century Swiss-German physician, Paracelsus, declared: “The art of healing comes from nature, not
from the physician” [5]. These insights have lead SY researchers to investigate the modern health
benefits of humans being exposed to nature or GS.
Several studies explored the therapeutic benefits of SY in Asian countries [2,3,9,11].
Physiological and psychological differences between participants in a “forest therapy (FT)” program
and a control were examined in the Seoul Metropolitan area with findings of a significant reduction
in chronic widespread pain and depression [3]. Song and colleagues [9] demonstrated how male
Japanese students who walked 15-min in an urban park during the autumn season had decreased
stress and heart rates. By using several valid psychological tests, researchers demonstrated the
positive effects of FT on individuals coping with chronic side effects of a cerebral vascular accident -
specifically anxiety and depression [2]. At the Center for Environment, Health, and Field Sciences,
Chiba University, Japan, researchers measured oxyhemoglobin levels in the pre-frontal cortexes of
research participants while the participants observed three dracaena plants [11]. Results indicated a
Int. J. Environ. Res. Public Health 2017, 14, 851 3 of 37
significant increase in participants’ oxyhemoglobin levels for urban, domestic and workplace foliage
effects which directly demonstrates the health-promotion effects associated with indoor foliage
plants on humans [11].
While exploring recent research about the health benefits associated with SY a dearth of scientific
research conducted in Western populations was determined. Therefore, the increasing interest and
the current published significant research findings surrounding the healing benefits related to SY, GS
and the wilderness offers healthcare professionals an opportunity to delve deeper into this
complementary modality for the prevention of disease and to assist with the potential healing of
certain existing conditions in Western cultures. Revealing current research methods and subsequent
research outcomes associated with SY practices may provide researchers, clinicians and students with
an intervention that assists with preventative medicine and evidence-based practice (EBP). Therefore,
the aim of this paper is to offer: (a) an in-depth inquiry of the current literature, (b) invite researchers
residing in Western cultures to design and conduct empirical research regarding the therapeutic
benefits associated with SY and, (c) to encourage healthcare providers/students to consider practicing
SY to decrease undue stress and potential disconnection.
2. Materials and Methods
Review Method
The terms of this comprehensive review were to emphasize the core elements of the research
proposition. The initial literature search was conducted with the intention of identifying publications
that offered significant historic relevance to the practice of SY, included various populations, sample
sizes and geographic locales, utilized evidence-based practices, illustrated measurable physiological
and psychological effect parameters, expounded upon practical frameworks and methodologies for
the practice of SY, explicated unique measurable criteria for the application of SY and deduced
limitations of previous research.
Search Method
The electronic databases searched included PubMed Central, PubMed, CINAHL, Scopus, and
PsycINFO (Figure 2). Hand searched bibliographies and reference lists from seminal researchers of
SY were also applied to the initial culling of publications. PubMed Central was searched to ensure
the incorporation of relevant publications not indexed in PubMed. Keywords were used for each
database and during snowball searches. All titles and abstracts were searched with the following
terms: “shinrin-yoku,” “forest bathing,” and “nature therapy.” These searches were combined with
the Boolean operators AND/OR. These terms were chosen from careful analyses of supporting
literature. For example, the aforementioned terms “nature therapy”, “shinrin-yoku”, and “forest
therapy” are used in conjunction with one another in the most recent scholarly literature review of
NT in Japan [9].
To remain prescient, the reference range utilized in this review included literature published
between the years 2007 and 2017. Therefore, the inclusion criteria allowed for publications that were
available in English, dated from 2007 to 2017, incorporated transparent evidence based practices in
reviews or trials, included robust quantitative and/or qualitative data, offered unique frameworks
and theories, and explored current trends in research. Studies not meeting the tenets of this criteria,
specifically those that pertained to physical exercise, fitness, landscape architecture, and laboratory,
or animal studies were withdrawn from considerations.
Int. J. Environ. Res. Public Health 2017, 14, 851 4 of 37
Figure 2. Literature search process.
3. Results
The findings of all relevant studies were synthesized (Table 1). The initial literature search
revealed a series of topical themes apropos of the research aim. Articles were grouped into categories
reflecting upon their most pertinent features. These categories include Background information,
Frameworks, Physiological and Psychological effects, Sensory Metrics, and Limitations to findings.
Previous Systematic Reviews and Literature Reviews were identified. Characteristics of publications
specific to the themes of Physiological and Psychological Effects (PP), Sensory Metrics (SM), which is
a subtopic of PP, and Frameworks (F) are delineated, an explicated within the key in Table 1.
3.1. Physiological and Psychological (PP) Effects
Livni [12] published an editorial on the health benefits of SY and described the historic trends in
biophysical and psychosocial research. While news of the beneficial elements of SY has been
gathering momentum in popular lexicon, it has been the robustness of pioneering research, largely
from Japanese scholars, that illuminates empirical links between the PP effects of SY. Tsunetsugu,
Park and Miyazaki [13] conducted a novel review representing a didactic integration of various
parameters specific to central nervous system (CNS) activity biomarkers; heart-rate variability
(HRV), salivary cortisol levels (SCL), immunoglobulin A (IgA) and sense-specific metrics.
Of the studies included within the PP section, and irrespective of study aims, there was a trend
towards small sample sizes, gender and age homogeneity, and skewed ratios of females to males/vice
versa, which by either methods of convenience, purpose and/or imparted bias to the research. An
overwhelming number of studies included homogenous gender sampling [14–27]. Population
demographics specific to gender were unreported in [28–30]. Proportionately skewed ratios of male
Int. J. Environ. Res. Public Health 2017, 14, 851 5 of 37
to females and vice versa were identified in these studies [31–36]. Studies may have been limited to
research participants specific to the student body of the courses and facilities within which the
research was designed. The aspects of cultural specificities and sensitivity in research design must be
considered when approaching a literature review from a global lens. The methods, tests, and findings
of 40 relevant publications expounding upon the PP indices are included in this review. These
publications are further assorted into Heart-rate Metrics; Disease States; Autonomic Nervous System
Effects; Endocrine Function; and Sense Metrics. The multitudinous reasons for natural environs
generating the aforementioned positive qualities have been systematically incorporated into the
investigation of the physiological and psychological effects of SY as follows.
3.2. Heart-Rate Metrics
As changes in cardiac function, revealed by cardiac monitoring, are correlational to the
physiological effects of stress regardless of environmental setting, it is coherently expected more than
one third of the articles reviewed observe not only standard vital signs, including heart rate (HR) and
pulse rate (PR), systolic and diastolic blood pressure (SBP/DBP) and ECG interpretation, but also heart
rate variability (HRV), as well as left ventricular function and right ventricular function (LVF/RVF).
While LVF is attributed to the ability of the left ventricle to perfuse the body, RVF is related to
pumping blood to the lungs. HRV is defined as the variation in the time interval between heartbeats
and is associated with the activation of the parasympathetic nervous system (PNS) through high
frequencies (HF) and the sympathetic nervous system (SNS) through low frequencies (LF).
Int. J. Environ. Res. Public Health 2017, 14, 851 6 of 37
Table 1. Characteristics of selected studies and supporting evidence.
Study Country Population Sample Setting Aim & Design Findings
Bowler
[1] UK
Articles were culled from
PubMed, EMBASE, CINAHL,
PsycINFO, Web of Science,
SPORTDiscus, ASSIA, HMIC
Data, LILACS, UK Natl.
Research Register archives,
TRIP database, UK Natl. Lib. for
Health, Index to Theses Online,
Directory of Open Access
J
ournals, Economic and Social
Data Service, Database of
Promoting Health Effectiveness
Reviews, Trials Register of
Promoting Health
Interventions, Cochrane Collab.,
Campbell Collab.
Article total = 25. Studies
that met the review inclusion
criteria included crossover or
controlled trials, which
investigated the effects of
short-term exposure to each
environment during a walk
or run. Including ‘natural’
environments, such as public
parks and green university
campuses, and synthetic
environments, such as
indoor and outdoor built
environments.
Centre for Evidence-Based
Conservation at the School of
the Environment and Natural
Resources, Bangor University,
Bangor, Gwynedd, United
Kingdom.
Systematic review to collate and synthesize the
findings of studies that compare measurements of
health or well-being in natural and synthetic
environments. Effect sizes of the differences between
environments were calculated and meta-analysis
used to synthesize data from studies measuring
similar outcomes.
PP
The studies suggested that natural
environments may have direct and
positive impacts on several aspects
of health and well-being.
Chun [2] Korea
Chronic stroke patients
recruited from a stroke welfare
center in the Republic of Korea.
Of those included: 31 patients
had a history of cerebral
infarcts, and 28 with a history of
intracerebral hemorrhage.
N = 59; 40 men, 19 women;
60.8 ± 9.1 years of age with
an age range of 36–79 years.
Settings included a recreational
forest area in Gyenggi-do,
Republic of Korea. The urban
group stayed in a hotel
Gyenggi-do in the Republic of
Korea.
Assessment of forest therapy effectiveness for
treating depression and anxiety in patients with
chronic stroke by using psychological tests. This
study measured reactive oxygen metabolite (d-
ROM) levels and biological antioxidant (BAPs)
potentials associated with psychological stress.
Patients were randomly assigned to a forest group
(recreational forest site) or urban group (staying in
an urban hotel). Scores on Beck’s Depression
Inventory, Hamilton Depression Scale, and the
Spielberger State Trait Anxiety Inventory were
analyzed.
PP
Forest groups had BDI, HAm-D17
and STAI scores were significantly
lower following treatment. BAPs
were significantly higher than
b
aseline. Urban group STI scores
were significantly higher following
treatment. Forest therapy is
b
eneficial for treating depression
and anxiety symptoms in patients
with chronic stroke and may be
useful in patients who can’t be
treated by standard
pharmacological or
electroconvulsive therapies.
Han [3] Korea
Employees of a public
organization providing building
and facilities management
services in Seoul Metro area, all
of whom were diagnosed with
N = 61; 35 females and 26
males; randomly assigned to
the either the experimental
forest therapy group
(n = 33), or the control
group (n = 28).
Forest therapy intervention
took place at a campsite at the
Saneum Natural Recreation
Forest in Yangpyeong county
of Gyeonggi Province.
Additional assessments were
To explore the effects of a 2-day forest therapy
program on those with chronic widespread pain.
Measures assessed included the following: pre- post
heart rate variability, natural killer cell, self-reported
pain, depression level and health related quality of
life.
Forest therapy participants
reported significant decreases in
pain, depression and increased
QOL. Forest therapy is an effective
intervention to relieve
Int. J. Environ. Res. Public Health 2017, 14, 851 7 of 37
Chronic Widespread Pain
(CWP).
taken at the Inje University
Seoul Paik Hospital in the
urban environment.
PP psychological and physiological
pain.
Anonym
ous [4] Supporting material NA NA Shinrin Yoku. A website describing the practice of
SY and programs offered for forest guide training. NA
Williams
[5] Supporting material NA NA An article presented in the National Geographic
magazine about the effects of NT. NA
Kaplan
[6] Supporting material NA NA A book about Kaplan’s Attention Restorative
Hypothesis. NA
Ulrich [7] Supporting material NA NA An article about Ulrich’s Stress Reduction
Hypothesis. NA
Kellert [8] Supporting material NA NA A book explaining the Biophilia Hypothesis. NA
Song [9] Japan
Researchers culled articles from
the Pubmed database using
various keywords.
Article total: 52 NA
Literature review aimed to objectively demonstrate
the physiological effects of NT. Reviewed research
findings in Japan related to the green space, plants
and wooden material and the analysis of differences
that arise therein.
PP
Researchers elucidated various
scientific data, which assessed
physiological indicators, such as
b
rain activity, autonomic nervous
activity, endocrine activity,
immune activity are accumulating
from the field and lab experiments.
NT will play a significant role in
preventative medicine in the
future.
Sifferlin
[10] Supporting material NA NA
A Time magazine article about the effects of living
and interacting in green spaces. Results indicate
people are more energetic, in good overall health
and have more of a sense of meaningful purpose in
life.
NA
Igarashi
[11] Japan
Female students from the
University of Chiba, Japan,
deemed healthy at the time of
the study.
N = 18; adult female
university students with a
mean age of 21.6 ± 1.5 years.
Artificial climate chamber in a
laboratory of the Center for
Environment, Health, and Field
Sciences, Chiba University,
apan.
Quantitative study was to determine if images of
natural objects elicited similar neural responses
(activation of the prefrontal cortex) as those brought
about with the interaction of real objects.
Physiological measurements were performed in an
artificial climate chamber maintained at 25 °C with
50% relative humidity and 300 lux illumination. For
foliage plants three dracaena plants (Dracaena
deremensis) were used. Oxy-hemoglobin
concentrations in the prefrontal cortex were assessed
with time-resolved near-infrared spectroscopy.
SM
Subjects viewing actual live plants
had significantly increased oxy-
hemoglobin concentrations in the
prefrontal cortex. Subjective
ratings of “comfortable vs.
uncomfortable” and “relaxed vs.
awakening” were similar for both
live and artificial plants. Results
were significant for the benefits for
urban, domestic and workplace
foliage.
Int. J. Environ. Res. Public Health 2017, 14, 851 8 of 37
Livni [12] Supporting material NA NA The Japanese practice of ‘Forest Bathing’ as
scientifically proven to improve your health. NA
Tsunetsu
gu [13] Japan N/A
Author-researchers culled
articles for this literature
review from a studies rooted
in physiological data, data
collected from field
experiments in forest
settings, laboratory settings,
and studies categorized into
sub-themes specific to the
five-senses. Exact literature
search methodology and
total number of articles
culled unknown.
N/A
To investigate the physiological effects of Shinrin-
yoku according to specific themes centered on the
health applications of FB. The authors reviewed
previous physiological experiments with trials in
forests and laboratory settings, to determine the
physiological effects on individuals from exposure to
forests and elements of forest settings. Metrics
investigated included: physiological measurements
of central nervous activity, autonomic nervous
activity, and biomarkers reflecting stress response.
PP
Author-researchers summarized
the separate elements of forests in
terms of the five senses, and
provide contribution to effects of
Shinrin-yoku within the
framework of the “Therapeutic
Effects of Forests” project.
Jo [14] Japan
Participants comprised Japanese
male graduate and
undergraduate students at
Chiba University, recruited
from landscape and horticulture
programs.
N = 26; males aged early to
mid- twenties mean age 24 ±
1.8 years.
Chiba University in a screened
room, such that the participants
were blinded to the observers.
Quantitative. Controlled trial without
randomization. The aim of this study was to
elucidate how floral fragrance could impact human
health; specifically, the psycho-physiological
responses to the floral scent of the Japanese plum
b
lossom. Changes in cerebral activity were measured
b
y multichannel near-infrared spectroscopy. Pulse
rate, heart-rate variability and arterial blood
pressure were taken. The brief-form Japanese
version Profile of Mood States questionnaire (POMS)
tested for psychological stress.
SM
Sensory stimuli from plants may
reduce stress and provide a
general sense of wellbeing among
this population. Hypothesis was
supported by the data.
Igarashi
[15] Japan
Seventeen Japanese adult
females were recruited from a
population living within the
urban suburbs of Kashiwa in
the Chiba Prefecture of Japan.
All were deemed healthy prior
to the experiment.
N = 17; Adult Japanese
females with a mean age of
46.1 ± 8.2 years.
Kiwifruit orchard adjacent to
the Center for Environment,
Health and Field Sciences,
Chiba University, Japan.
Physiological and psychological relaxation effects of
viewing kiwifruit orchard landscapes in
summertime in Japan were investigated.
Quantitative, randomized controlled trial wherein
subjects viewed a kiwifruit orchard landscape or a
b
uilding site (control) for 10 min. Intervals. HRV and
HR were measured continuously. Modified semantic
differential method and short-form Profile of Mood
States (POMS) were determined.
SM
Significant increase in PNS activity
and marginally significant
decrease in HR and an increase in
comfortable, relaxed and natural
feelings and a significant
improvement in mood states.
Ikei [16] Japan Female students from the
University of Chiba, Japan,
N = 13; adult female
university students with a
mean age of 21.5 ± 1.0 years.
Center for Environment,
Health and Field Sciences,
Chiba University, Japan.
Quantitative controlled trial without randomization
was to determine the effects of olfactory-stimulation
of the alpha-pinene (a volatile compound in
Olfactory stimulation by a-pinene
significantly increased the High
Frequency measure of HRV, which
Int. J. Environ. Res. Public Health 2017, 14, 851 9 of 37
deemed healthy at the time of
the study.
J
apanese cedar wood) on autonomic and
parasympathetic nervous system activity. Measures
were taken at 30 s before and 90 s during/after smell
admin. HRV and HR were measured. HR
SM
is associated with parasympathetic
nervous activity, and decreased
HR overall—these are signs of
increased physiologic relaxation.
Kobayash
i [17] Japan
The study consisted of 456
J
apanese male students at the
University of Chiba, Japan,
deemed healthy at the time of
the study.
N = 456; Males aged 20 to 29
years old (mean, 21.9 ± 1.6
years).
Experimental design and
procedures took place at the
Forestry and Forest Products
Research Institute and Center
for Environment, Health and
Field Sciences, Chiba
University, Japan.
To deduce and present the “normative values,” or
“reference” range of heart rate variability (measured
in 417 young male students), and salivary alpha-
amylase in 430 “healthy” male students from Chiba
University with an emphasis on the distribution and
reproducibility of the values. Measures within this
quantitative study included: short-term HRV; beat to
b
eat HR recorded at 2 min intervals with
portable/wearable HR monitor Salivary alpha-
amylase measurements taken before breakfast (6:30
to 7:30 a.m.) after subjects sat “resting” 1 min.
PP
Results suggested a relatively
small correlation between HRV
and salivary alpha-amylase. This
study is mostly indicative of intra-
individual variability in measures.
Provides example of metrics we
can use in our study as well as
“normative” values.
Kobayash
i [18] Japan
The population consisted of in
267 male students from The
University of Chiba, Japan,
deemed healthy at the time of
the study.
N = 267: Males with a mean
age of 21.7 ± 1.5 years.
Chiba University’s research
labs and additional laboratory
studies performed at the
laboratories of SRL Inc. in
Tokyo, Japan.
Quantitative study aimed to specify the normal
salivary cortisol levels, and reference ranges in
subjects at University of Chiba, as a relatively
innocuous biomarker for stress levels during the
mornings on two consecutive days, which were
analyzed by radioimmunoassay. Quantitative. Saliva
collected before breakfast, appx. 20–40 min after
awakening (6:30–7:30 a.m.) and again before
participants brushed teeth. Each subject rested for 1
min in a sitting position before saliva collection.
Measures were repeated the following day.
PP
Consistency and reliability
(“distribution characteristics”) of
salivary cortisol measures were
reported to be steadier in the
morning samples ~30–45 min after
waking.
Koga [19] Japan
J
apanese male students from
The University of Chiba were
recruited for this study.
N = 14; Males with an age
range of 21–27 years.
Laboratory rooms at The
University of Chiba, Japan.
Quasi-experimental study was to gauge the feeling
elicited by (with eyes closed), touching four different
“tactile” samples: a plate of aluminum, a piece of
velveteen, leaf of natural Epipremnum aureum, and
an artificial resin-made leaf, for about ~120 s.
Measures included pre and posttest psychological
and physiological indices, Cerebral Blood Flow
(hemodynamics) measured via near infrared
spectroscopy (NIRS; NIRO-300; Hamamatsu
Photonics, JAPAN); measured pre and post
Participants successfully reported
feeling a measurable sense of
“calm” when touching natural
plant material, as opposed to the
other materials
Int. J. Environ. Res. Public Health 2017, 14, 851 10 of 37
stimulus. Psychological data were acquired using a
semantic differential questionnaire.
SM
Lee [20] Japan Male students from the
University of Chiba, Japan.
N = 24; Japanese males with
a mean age of 24.9 ± 2.1.
Settings included laboratory
rooms at The University of
Chiba, Japan.
To examine the psychological and physiological
b
enefits of interaction with indoor plants vs.
computer tasks. Researchers implemented a
quantitative crossover experimental design.
Participants were randomly distributed into 2
groups (n = 12 plants; n = 12 computer task).
PP
Feelings during the transplanting
task were different from that
during the computer task. Feeling
more comfortable, soothed, and
natural after the transplanting task
Sympathetic activity increased
over time during the computer
task but decreased at the end of the
transplanting task. Diastolic BP
lower after transplanting task.
Lee [21] Japan
Twelve young Japanese male
adults were recruited from local
universities. At the recruitment
stage, those who had past or
current mental disorders, and
those with cardiovascular or
allergic diseases were screened.
Those who were habituated to
smoking or drinking were
excluded. The adults who
participated in the study had a
mean age of 21.2 years
[standard deviation (SD) 0.9].
N = 12; Japanese males with
a mean age of 21.
Field experiments were
performed at two different sites
(forest and urban) in Hokkaido
Prefecture, Japan. The forest
site was characterized by
b
road-leaved deciduous trees
and was located in Tsurui
Village. The urban site was a
typical commercial area
situated in the town of Kushiro.
To provide scientific evidence supporting the
efficacy of FB as a natural therapy by investigating
its physiological benefits using biological indicators
in outdoor settings. 3 days 2-night study.
Physiological responses as well as self-reported
psychological responses to forest and urban
environmental stimuli were measured in real
settings.
PP
Results of each indicator were
compared against each
environmental stimulus. HF power
analysis, which reflects the activity
of the parasympathetic nervous
system, significantly higher values
were obtained for forest stimuli
than urban stimuli. Additionally,
LF/HF ratio values of HRV, which
mediate the activity of the
sympathetic nervous system, were
significantly lower in the forest
than at the urban site.
Lee [22] Japan
Male students ages 21–22 at
Chiba University in Japan were
recruited to participate in the
walking programs. All were
deemed healthy at the outset of
the trials.
N = Japanese males with a
mean age of 21.1 ± 1.2 years.
Field experiments were
performed at four different
sites in Japan including:
Yoshino Town in Nara
Prefecture, Akiota Town in
Hiroshima Prefecture, Kamiichi
Town in Toyama Prefecture,
and Oita City in Oita
Prefecture. Data analysis
performed at The University of
Chiba, Japan.
Quasi-experimental study aimed to compare the
effects of a forest walking therapy program with an
Urban walking program over 2 consecutive days to
determine the cardiovascular relaxation indices.
Walks included 12–15 min of self-paced walking in
forest (4 sites selected throughout Japan) and urban
(the control) environments. HRV measured with a
portable ECG w/in 1 min intervals. 4 psychological
questionnaires delivered: semantic differential (SD)
techniques. Japanese version of the Profile of Mood
States (POMS). Anxiety levels studies with
Spielberger State-Trait Anxiety Inventory (STAI).
PP
Cardiovascular relaxation was
noted with the forest walking
therapy program, but not as with
the urban control -specifically the
differences in HRV and BP within
the two exposures. Psychological
tests are concurrent with these
findings.
Int. J. Environ. Res. Public Health 2017, 14, 851 11 of 37
Li [23] Japan
Male adult subjects were
selected from four large
companies in Tokyo, Japan.
Subjects having infectious
disease, utilizing
immunosuppressive drugs
and/or other relevant
medications were ruled out.
Subjects were deemed healthy
at the time of the trial.
N = 12; Males aged 35–56
years, with a mean age of
45.1 ± 6.7.
Various forested and urban
locations across Japan.
Specifically, the FB groups
experienced three different
forest areas in Agematsu town
in Nagano prefecture of
northwest Japan. Whereas the
city group experienced Nagoya
city located in Aichi prefecture
in the center of Japan.
To study NK activity in both forest and urban
environments.
Twelve healthy male subjects, age 35–56 years,
experienced a three-day/two-night trip to forest
fields and to a city, in which activity levels during
b
oth trips were matched. On day 1, subjects walked
for two hours in the afternoon in a forest field; and
on day 2, they walked for two hours in the morning
and afternoon, respectively, in two different forest
fields; and on day 3, the subjects finished the trip
and returned to Tokyo after drawing blood samples
and completing the questionnaire. Blood and urine
were sampled on the second and third days during
the trips, and on days 7 and 30 after the trip, and NK
activity, numbers of NK and T cells, and granulysin,
perforin, and granzymes A/B expressing
lymphocytes in the blood samples, and the
concentration of adrenaline in urine were measured.
Similar measurements were made before the trips on
a normal working day as the control.
PP
Phytoncide concentrations in forest
and city air were measured. The FB
trip significantly increased NK
activity and the numbers of NK,
perforin, granulysin, and
granzyme AlB-expressing cells and
significantly decreased the
concentration of adrenaline in
urine. The increased NK activity
lasted for more than 7 days after
the trip. In contrast, a city tourist
visit did not increase NK activity,
numbers of NK cells, nor the
expression of selected intracellular
anti-cancer proteins, and did not
decrease the concentration of
adrenaline in urine.
Mao [24] China
Male University students
deemed healthy at the time of
the trials without documented
history of physiological or
psychiatric disease and/or
disorder.
N = 20; Male age 20.79 ± 0.54
years.
Locations included the Wuchao
Mountain Forest in Hangzhou,
Zhejiang, China and the urban,
downtown district of
Hangzhou, China.
Quantitative randomized controlled trial was to
measure the effects of forest-bathing for short
periods of time on overall human health using a
variety of metrics. To investigate potentially positive
effects of FB on the subject’s health from the
standpoint of pathophysiological metrics. Subjects
were randomly divided into two groups. Forest site
and city site. Measures included: malondialdehyde
(MDA) concentrations, cytokine production, serum
cortisol, testosterone assay, lymphocyte assay, POMS
evaluations.
PP
Data supported the hypothesis that
several physiological and
psychological metrics were
presented in accordance with a
decrease in overall stress and
subsequent toxic physiologic
effects of stress.
Ochiai
[25] Japan
Participants included those
recruited from the Health
Promotion Center in Agematsu,
Nagano Prefecture. All
participants needed to be
Inclusion aged 40 years or older
N = 17 Female adults with an
average age of 62.2 ± 9.4
years.
Forest therapy phase was
conducted in Akasawa Shizen
Kyuyourin, Akasawa Natural
Recreation Forest, Agematsu,
Nagano Prefecture. Additional
assessment took place at the
To assess the psychological and physiological effects
of a forest therapy program on middle age adult
women. Measures included pulse rate, salivary
cortisol levels and psychological indices were taken
the day before and the day of forest therapy.
PP
Pulse rate, salivary cortisol levels
were significantly lower than
b
aseline indicating a physiological
relaxed state. Reported
significantly more comfortable,
relaxed and natural according to
the semantic differential. POMS
Int. J. Environ. Res. Public Health 2017, 14, 851 12 of 37
and deemed healthy at the time
of the study.
nearby health promotion
center.
negative mood subscale for tension
and anxiety was significantly
lower while the “vigor” was
significantly higher following
forest therapy. A significant
decrease in pulse, decrease in
salivary cortisol levels, increase in
positive feelings, decrease in
negative feelings. Substantial
b
enefit to middle age females.
Park [26] Japan
Participants included young
male Japanese university
students.
N = 168 Male (100%), mean
age 20.4 ± 4.1 years
14 forests and 14 urban areas
across Japan
To investigate the relationships between
psychological responses and either an urban or a
forest setting. Using both the SD method and POMS
questionnaire, comparisons were made for both the
walking and viewing phases within each area of
accommodation.
PP
Researchers found that
descriptions of the forest area
using the SD method were more
“enjoyable, friendly, natural, and
sacred”. There were also
significant differences among
POMS results for both the city and
forest areas.
Park [27] Japan
Male University students
recruited from Chiba
University, Japan.
N = 12; Males with an
average age of 22.8 ± 1.4
years.
The experimental trials took
place in a Seiwa Prefectural
Forest Park in Chiba Prefecture,
apan.
To investigate the physiological effects of Shinrin-
yoku using salivary cortisol and cerebral activity as
indicators. On the first day of the experiment, one
group of 6 subjects was sent to a forest area, the
other 6 were sent to a city area. On the second day,
each group was sent to the opposite area for a cross
check. In the morning, the subjects were asked to
walk around their location for 20 min. In the
afternoon, they were asked to sit on chairs and
watch the landscapes of their set locale for 20 min.
Prefrontal cortical cerebral activity and salivary
cortisol were measured before and after walking in
the forest, or city locations and before and after
watching the landscapes in the afternoon in the
forest and city areas.
PP
Results indicated that cerebral
activity in the prefrontal area of the
forest area group was significantly
lower than that of the group in the
city area after walking; the
concentration of salivary cortisol in
the forest area group was
significantly lower than that of the
group in the city area before and
after watching each landscape. The
results of the physiological
measurements show that Shinrin-
yoku can effectively relax both
people’s body and spirit.
Joung
[28] Korea
Eight Korean university
students participated in this
study. The subjects were
deemed physically and
mentally healthy prior to the
initiation of this study.
N = 8; Participants had an
age range of 22.0 ± 2.2 years.
Gender undocumented.
Forested-region located in
Dowon-ri, Toseong-myun,
Goseong-gun, Gangwon-do,
Korea. The contrasting urban
area was in Yuseong-gu,
Determine if forest environments have physiological
and psychological relaxing effects by viewing a
forest area compared with viewing an urban area
from the roof of an urban building without being
watched by others. Near-infrared spectroscopy
measurement was performed on subjects while they
Total hgb and oxyhemoglobin
concentrations were significantly
lower in their forest area than the
urban area. Comfortable, natural,
and soothed were significantly
higher in the forest vs. urban area.
Int. J. Environ. Res. Public Health 2017, 14, 851 13 of 37
Daejeon Metropolitan City,
Korea.
viewed scenery for 15 min. At each experimental site
(forest and urban) Total hgb and oxyhemoglobin
concentrations were measured.
SM
For mood states, the forest group
had significantly lower negative
emotions.
Mao [29] China
Subjects included patients
diagnosed with essential
hypertension in stable condition
at the time of the study. All
were being treated in
Hangzhou, China.
N = 24; Adults, aged from 60
to 75 years, specific
demographics unknown.
Broad-leaved evergreen forest
“White Horse Mountain
National Forest Park” in
Suichang, County, Zhejiang
Province, China. For
comparison, the control city
was an urban area in
Hangzhou, China.
Quantitative randomized controlled trial was to
provide scientific evidence to support the use and
efficacy of SY as a practical application for treating,
or ameliorating essential hypertension in the elderly.
Patients with essential hypertension were randomly
divided into a field study group and a control group
of 12 persons each. The intervention (field study)
group went to a broad-leaved evergreen forest to
experience a 7-day/7-night trip, and the control
group experienced a city area in Hangzhou for
control. Measurements of the following were
collected: blood pressure indicators, cardiovascular
disease-related pathological factors including
endothelin-1, homocysteine, renin, angiotensinogen,
angiotensin II, angiotensin II type 1 receptor,
angiotensin II type 2 receptor, inflammatory
cytokines interleukin-6 and tumor necrosis factor
were detected. The profile of mood states (POMS)
was used for psychological indicators.
PP
Results of this study demonstrated
that there is direct evidence to
support the application of SY for
the amelioration of essential
hypertension in the population
studied. Data indicates that SY
practices contribute to the
inhibition of the renin–angiotensin
system and inflammation, thereby
reducing cardiac workload and
further stress on the heart when
compared with the urban control.
McCaffre
y [30] USA
Participants included older
adults over the age of 65 with
depression.
N = 40 (mean age = 71.3
years) with depression
diagnosed by a physician.
Morikami Gardens, Florida
To determine the effects of garden walking on
depression in older adults. Participants were asked
to complete 12 two- hour garden walks during a 3-
month period. Throughout the walks, they were
asked to read a descriptive paragraph and journal
upon reaching specified locations within the
gardens. Pictures of these locations were also
provided so that journaling could continue when the
participants were away from the gardens as well.
PP
Mean scores on the Geriatric
Depression Scale decreased from
13 to 9.4 after completion of the 12
forest walks.
Kim [31] Korea
Patients recruited for this study
were among a population
diagnosed with major
depressive disorder at one
university hospital located in
Seoul, Republic of Korea.
N = 63 males and females; 23
in the forest group, 19 in the
hospital group, and 21 in the
control group.
Settings were the following; the
forest program took place at
the Hong-Reung arboretum,
while the hospital program
took place at the Seoul Paik
Hospital.
To test the effect of cognitive behavior therapy
(CBT)-based psychotherapy applied in a forest
environment on major depressive disorder. Tests
used included the Hamilton Rating Scales for
Depression (HRSD) scores of the forest group were
significantly decreased after 4 sessions compared
CBT-based psychotherapy applied
in the forest environment was
helpful in the achievement of
depression remission, and its effect
was superior to that of
psychotherapy performed in the
Int. J. Environ. Res. Public Health 2017, 14, 851 14 of 37
with controls. Montgomery-Asberg Depression
Rating Scales (MADRS) scores of the forest group
were significantly decreased compared with both the
hospital group and the controls. The remission rate
(7 and below in HRSD) of the forest group was 61%
(14/23), significantly higher than both the hospital
group (21%, 4/19) and the controls (5%, 1/21).
PP
hospital and the usual outpatient
management.
Morita
[32] Japan
71 healthy adult volunteers
participated in this study. Ages
ranged from teens to late 70s.
N = 71; 43 males and 28
females.
Ryukoku Forest of Ryukoku
University in Shiga Prefecture,
located in the western region of
Honshu, Japan. Data analysis
took place at the University of
Shiga, Japan.
Pre and posttest study was to evaluate the
immediate effects of forest walking in a community-
b
ased population with sleep complaints. Two-hour
forest-walking sessions were conducted on 8
different weekend days. Sleep conditions were
compared between the nights before and after
walking in a forest by self-administered
questionnaire and actigraphy data.
PP
Results indicated that 2 h of forest
walking improved sleep
characteristics; impacting actual
sleep time, immobile minutes, self-
rated depth of sleep, and sleep
quality.
Nakau
[33] Japan
Patients were recruited from a
pool of cancer patients,
specifically those with breast
cancer, or lung cancer of
various stages. For all
participants, one month passed
after they had undergone
surgery, chemotherapy, or
radiation and were in stable
condition at the time of study.
All participants resided in
urban areas and lacked access to
green, outdoor environments.
N = 22; Men and women
with a mean age of 58.1
years +/10.8 years.
Participants included 4
males with an average age of
65.3 and 18 females with an
average age of 56.6 years.
Within the Kyoto prefecture of
J
apan, sites included: The Japan
World Exposition 70
Commemorative Park (Suita,
Osaka Pref, Japan), parks,
forests, and gardens within the
park, horticultural settings,
participants’ homes, and a local
day treatment facility.
While watching a yoga video.
To explore the impacts of spiritual care and
integration of the natural environments in terms of
its’ impact on 22 cancer patients. Specifically, the
integrative treatment protocol consisted of forest
therapy, horticultural therapy, yoga meditation, and
support group therapy sessions were conducted
once a week for 12 weeks. The spirituality (the
Functional Assessment of Chronic Illness Therapy-
Spiritual well-being), quality of life (Short Form-36
Health Survey Questionnaire), fatigue (Cancer
Fatigue Scale), psychological state (Profile of Mood
States, short form, and State-Trait Anxiety
Inventory) and natural killer cell activity were
metrics assessed before and after the sessions.
PP
There were dramatic shifts pre and
post intervention to support the
hypothesis aforementioned.
Emotional and spiritual health
improved for all participants. This
study helps to delineate what is
meant by “spiritual well-being”
with specific questionnaires from
which we can glean much in terms
of semantics.
Ohtsuka
[34] Japan
Researchers culled their
participants from a sample of
patients being treated for Type
II Diabetes with an age range of
60–83, mean height 154.0 cm ±
1.3, and mean body mass index
(BMI) of 23.6 ± 0.4 kg/m2.
Additionally, researchers
N = 48 (16 males and 32
female) Type 2 Diabetic
patients with a mean age of
66.8 years.
Research facility and nearby
recreational areas in connection
with Hokkaido University,
apan.
Quantitative longitudinal study aimed to address
the effects of Shinrin-Yoku on blood glucose levels in
patients with Type II Diabetes. In an effort to
summarize data from future studies, the author of
this article noted that an additional sample of 116
persons, organized into 25 paired groups were
incorporated. Available data reflects these additional
participants.
Results demonstrated that Shinrin-
yoku and a decrease in blood
glucose are significantly correlated.
However, due to the additional
longitudinal participant sample
b
eing reported in the data, the
specificities of the total population
are unclear.
Int. J. Environ. Res. Public Health 2017, 14, 851 15 of 37
incorporated data from
longitudinal studies addressing
Type II Diabetic patients over a
period of 6 years. This increased
the sample to 116 persons, from
which 25 paired samples were
studied. Healthy subjects were
used as a control.
Of the initial sample (N = 48), 11 participants
experienced only dietary and exercise therapy, 27
were given oral medication, and 10 were being
treated with insulin administration at the time of,
and during the study.
Pre and posttest measures of blood glucose were
taken at specific timed intervals during the
intervention process. Participants were assessed after
morning meals at the research hospital. Peripheral
venous blood samples were collected for glucose
levels. Participants were divided into two forest-
walking groups. Glucose samples were drawn again
post Shinrin-yoku treatment.
PP
Shin [35] Korea
Subjects were adult males and
females diagnosed with
alcoholism and coming from
treatment at the Korean Alcohol
Research Center, Chungbuk
Province, South Korea. The
Korean Alcohol Research
Center is a national inpatient
alcohol rehabilitation facility.
N = 92; Adults 84 males, 8
females, aged ~44–49 yeas.
Saneum Recreational Forest, in
Kyungggi Province, South
Korea.
Quantitative case-control/cohort study with pretest
vs. posttest assessments. Subjects were assessed over
9-day while in a forest healing camp in Saneum
Recreational Forest, in Kyungggi Province, South
Korea, for the determining this therapy’s potential
treatment of depression for alcoholics. Measures
included The Beck Depression Inventory (BDI), and
a self-reported survey of 21 items relating to
personal variables and lifestyle metrics.
PP
Alcoholics with higher pre-test
depression levels improved on the
BDI post-test scores upon
completion of the forest program
more than participants with lower
pre-test depression levels.
Education level and marital status
of participants did not significantly
influence results.
Stigsdotte
r [36] Denmark
Initial sampling of data from
21,832 adults from Denmark
was used for this study. The
sample came from a 2005
nationally administered health
interview survey employing
region-stratified random
sampling from the Danish Civil
Registration
System. 10,250 individuals
responded and their data
recorded for this study.
N = 10,250; Adult Danes
aged 16–75 years, 5802 men
and 5448 women.
Utilized data from a previous
study taking place across
various regions of Denmark by
The Danish National Institute
of Public Health, University of
Southern Denmark.
Case study of pre-existing data. The aim of this
study was to research and determine the relevant
associations between access to green-space, health,
health-related quality of life indicators, and stress.
Data was collected from respondents following up of
a 2005 Danish Health Interview Survey. The data
was collected from face-to-face interviews and self-
administered questionnaires. Measures analyzed
included: the SF-36, (measuring eight dimensions of
health) and the Perceived Stress Scale. Multiple
logistic regression analyses were used to determine
the association between distance to green space and
self-perceptions stress.
PP
Results of this study demonstrate
that Danish individuals living
more than 1 km from green-space
reported lower satisfaction of
perceived health and quality of life
than those living less than 1 km to
accessible green-space.
Additionally, persons living less
than 1 km from a green-space
experienced less stress than
respondents living farther from
green-space. Respondents who
didn’t report stress were reported
to be more likely to visit green-
spaces than respondents reporting
stress. Overall, there was a viable
Int. J. Environ. Res. Public Health 2017, 14, 851 16 of 37
association between distance to
green-spaces and the health-
oriented variables in the research
question.
Park [37] Japan Male students from the Chiba
University, Japan.
N = 12; Male (100%), mean
age 21.8 ± 0.8
Conifer forest in Hinokage
Town , and Hyuga City in
Miyazaki Prefecture, Japan
Quantitative randomized controlled trial forest
recreation and its effects on the autonomic nervous
system were assessed. By random assignment, two
groups were formed into forest-area and urban-area
groups. Measures included heart rate and heart-rate
variability. The R-R interval of the electrocardiogram
was used to analyze how aspects of HRV reflect the
parasympathetic nervous activity sympathetic
nervous activity respectively. Pulse rate a blood
pressure were also measured.
PP
Pulse rate, diastolic blood pressure
and LF/(LF + HF) (LF—low
frequency, HF—high frequency)
components of HRV were
significantly lower in the forest
area than in the city area. HF
components of HRV tended to be
higher in the forest than in the city.
Forest recreation is effective for
relaxation of both the mind and
b
ody.
Park [38] Japan
Participants included young
male Japanese university
students.
N = 12; Male (100%), mean
age 21.3 ± 1.1
Areas of study included
Shinano town and Nagano city
in Nagano Prefecture.
To determine the physiological effects of SY. Day
one of the experiment required that six subjects went
to the forest area, and the other six went to a city
area. On the second day, subjects went to the
opposite of their previously assigned areas. During
the morning and evening within the area of
accommodation, heart rate variability (HRV),
salivary cortisol and pulse rate were measured, In
the afternoon, they were seated on chairs watching
the landscapes of their given area for 15 min. The
aforementioned physiological indices were again
measured before and after watching the landscapes
in the given field areas.
PP
Researchers found that HRV of
subjects in the forest area was
significantly higher than that of
subjects in the city area. On the
other hand, both pulse rate and
salivary cortisol concentration of
subjects in the forest area was
significantly lower than that of
subjects in the city area.
Song [39] Japan Male students from the Chiba
University, Japan.
N = 23; Male (100%), mean
age 22.3 ± 1.2
Kashiwa-no-ha Park in
Kashiwa City, Chiba
Prefecture, Japan, with a
nearby city area denoted as the
urban control site.
Quantitative. Non-randomized controlled trial,
within-subjects design. The aim of this study was to
demonstrate how the intervention of walking in
urban parks during the fall season impacted
participants’ heart-rate and stress levels. Students
walked 15 min each on specific trails in a park and in
a nearby urban area (the control). HR, HRV, the State
Trait Anxiety Inventory, and POMS, were measured
to assess the difference outcomes between walk-
sites.
PP
The walk in the park enhanced
relaxation in the participants via
parasympathetic nervous system
stimulation, while sympathetic
nervous system stimulation was
decreased. Heart-rate lowered
overall. Suggests the effectiveness
of even “small” green areas on
heart-rate variability.
Int. J. Environ. Res. Public Health 2017, 14, 851 17 of 37
Tsunetsu
gu [40] Japan
Male university students were
recruited for this study. All
were deemed healthy at the
time of the trial.
N = 12; Males aged 21 to 23
(mean ± SD: 22.0 ± 1.0).
Conducted in a broadleaf forest
mainly Nukumidaira, Oguni,
Yamagata, Japan.
To study the physiological effects of SY were
examined by investigating blood pressure, pulse
rate, heart rate variability (HRV), salivary cortisol
concentration, and immunoglobulin A concentration
in saliva. Subjective feelings of being “comfortable”,
“calm”, and “refreshed” were also assessed by
questionnaire. Physiological measurements were
conducted six times, i.e., in the morning and evening
b
efore meals at the place of accommodation, before
and after the subjects walked a predetermined
course in the forest and city areas for 15 min, and
b
efore and after they sat still on a chair watching the
scenery in the respective areas for 15 min.
PP
Data of the study revealed that
b
lood pressure and pulse rate were
significantly lower, and that the
power of the HF component of the
HRV tended to be higher and
LF/(LF + HF) tended to be lower.
Salivary cortisol concentration was
significantly lower in the forest
area, and feelings of comfort were
significantly higher in the forest
area.
Song [41] Japan
Participants recruited for this
study were adult male Japanese
citizens with a history of
prehypertension and/or current
hypertension deemed in
suitable physical condition to
participate in this study.
N = 20; Adult men with a
mean age of 58.0 ± 10.6
years.
Akasawa Shizen Kyuyourin;
Akasawa natural recreation
forest within Agematsu town
of Nagano Prefecture in central
J
apan. The control was a city
area within A City of Nagano
Prefecture, Japan.
To look at the effects of forest walking on the
autonomic nervous system in middle aged
hypertensive adults. Subjects were instructed to
walk predetermined courses in forest and urban
(control). The course length was 17-min. Walk
walking speed and energy expenditure were equal
b
etween both groups. HRV and HR were used to
quantify physiological responses.
PP
HR significantly lower and high
frequency component of HRV was
significantly higher. Questionnaire
results indicate after walking in the
forest the feelings were increased
around comfortable, relaxed,
natural, vigorous, decreased
tension and anxiety, depression,
anxiety hostility, fatigue and
confusion. A brief walk in the
forest elicited psychological
relaxation and physiological calm
on the subjects.
Kardan
[42] Canada Large urban population in
Toronto, Canada.
Tree lined streets in urban
neighborhoods.
The study was conducted in
Toronto, Canada.
Multivariate study combining high-resolution
satellite imagery and individual tree data from
Toronto with self-reports of general health
perception, cardio-metabolic conditions and mental
illness derived from the Ontario Health Study.
Having 10 or more trees in a city
b
lock improves health perception
in a way that is like an increase in
annual personal salary of $10,000.
And, having 11 more trees in a city
b
lock decreased cardio-metabolic
conditions in ways compared to an
increase in an annual personal
income of $20,000.
Grazulevi
ciene [43] Lithuania
20 male and female residents of
Kaunas, Lithuania each with a
diagnosis of Coronary Artery
Disease and cardiac
N = 20; Male and female
participants with a mean age
of 62.3 ± 12.6 years.
The study was conducted in
Kaunas. The urban exposure
area was a street near the
Hospital of Lithuanian U.
Quantitative Randomized Controlled Trial was to
study the impact of forest-walking on patients being
treated for CAD. Participants were randomly
assigned to either green or urban exposure groups
Walking in a park had a more
positive effect on overall cardiac
function in patients than walking
in urban environments.
Int. J. Environ. Res. Public Health 2017, 14, 851 18 of 37
comorbidities being treated at
the Cardiologic Clinic of the
Hospital of Lithuanian
University of Health Sciences.
Cardiology Clinic. The green
exposure region was a pine tree
park located near the
Cardiology Clinic.
and walked in these different environments for 30
min on 7 consecutive days. Researchers aimed to
determine how the different environments impacted
patients’ hemodynamics and state of their CAD
diagnoses. Testing involved pretest phenotype
questionnaires, various health assessment tools
including: SBP, DBP, HR, PWV, ECG, W (workload),
Spiroergometry.
PP
Jia [44] China
Adult patients diagnosed with
Chronic Obstructive Pulmonary
Disease, from the region of
Hangzhou, China, with no
exacerbations of COPD within 6
weeks of the trial.
N = 20; male and female
adult participants aged 60 to
79 years.
Hangzhou, China
Elucidate health effects of a FB trip on elderly
patients with chronic obstructive pulmonary disease
(COPD).
Subjects were randomly divided into two groups.
One group was sent to forest, and the other was sent
to an urban area as control. Flow cytometry, ELISA,
and profile of mood states (POMS) were evaluated.
PP
Within the forest group, there was
a significant decrease of perforin
and granzyme B expressions,
accompanied by decreased levels
of pro-inflammatory cytokines and
stress hormones. Meanwhile, the
scores in the negative subscales of
POMS decreased after FB trip.
These results indicate that FB trip
has health effect on elderly COPD
patients by reducing inflammation
and stress level.
Ohtsuka
[45] Japan
Researchers culled their
participants from a sample of
patients being treated for Type
II Diabetes with an age range of
60–83, mean height 154.0 ± 1.3
cm, and mean body mass index
(BMI) of 23.6 ± 0.4 kg/m2.
Additionally, researchers
incorporated data from
longitudinal studies addressing
Type II Diabetic patients over a
period of 6 years. This increased
the sample to 116 persons, from
which 25 paired samples were
studied. Healthy subjects were
used as a control.
N = 48 (16 males and 32
female) Type 2 Diabetic
patients with a mean age of
66.8 years.
Research facility and nearby
recreational areas in connection
with Hokkaido University,
apan.
Quantitative longitudinal study aimed to address
the effects of Shinrin-Yoku on blood glucose levels in
patients with Type II Diabetes. In an effort to
summarize data from future studies, the author of
this article noted that an additional sample of 116
persons, organized into 25 paired groups were
incorporated. Available data reflects these additional
participants.
Of the initial sample (n = 48), 11 participants
experienced only dietary and exercise therapy, 27
were given oral medication, and 10 were being
treated with insulin administration at the time of,
and during the study.
Pre and posttest measures of blood glucose were
taken at specific timed intervals during the
intervention process. Participants were assessed after
morning meals at the research hospital. Peripheral
venous blood samples were collected for glucose
levels. Participants were divided into two forest-
NA
Int. J. Environ. Res. Public Health 2017, 14, 851 19 of 37
walking groups. Glucose samples were drawn again
post Shinrin-yoku treatment.
PP
Morita
[46] Japan
71 healthy adult volunteers
participated in this study. Ages
ranged from teens to late 70s.
N = 71; 43 males and 28
females.
Ryukoku Forest of Ryukoku
University in Shiga Prefecture,
located in the western region of
Honshu, Japan. Data analysis
took place at the University of
Shiga, Japan.
Pre and posttest study was to evaluate the
immediate effects of forest walking in a community-
b
ased population with sleep complaints. Two-hour
forest-walking sessions were conducted on 8
different weekend days. Sleep conditions were
compared between the nights before and after
walking in a forest by self-administered
questionnaire and actigraphy data.
PP
Results indicated that 2 h of forest
walking improved sleep
characteristics; impacting actual
sleep time, immobile minutes, self-
rated depth of sleep, and sleep
quality.
Sung
[47]
The
Republic of
Korea
Recruitment included stable
patients with stage 1 HTN,
and/or patients who were on
antihypertensive medication.
N = 56; Males and females
aged 63–73 years.
The forest group participated at
two recreation forest sites
including Hoengseong and
Saneum, in Kangwon-do,
Republic of Korea. The control
group maintained regular
treatment at the treatment
facility.
To study the effects of a Forest Therapy/CBT-based
community program on adult patients with HTN,
referred from two local health centers in Seoul, S.
Korea. This study was a controlled trial without true
randomization. For an 8-week intervention duration
of the treatment protocol. Data included a
comparison of pre and post intervention measures
of: BP, A. Qol. (Quality of Life survey tool), and
salivary cortisol measurements of control group vs.
Forest Therapy program group, SBP and DBP
manual measurements.
PP
Forest Therapy/CBT-based
community program may have
initially reduced SBP measures,
marked decrease in salivary
cortisol levels, and improvement in
A Qol measures.
Largo-
Wight
[48]
USA
Full-time, desk-bound, and
otherwise sedentary office staff
(secretaries and clerks), at an
undisclosed southeastern
university in Florida, USA.
N = 503. Office staff at a
southeastern university.
Response rate (30%). Women
(92.9%) Caucasian (82.5%).
Mean age (42 years; SD 12
years) Appx. (47.5%) of all
participants attended college
or technical school. (49.5%)
reported annual income of
$25,001–$35,000 per year.
(54.4%) reported being
married.
Workplace (office)
environment at a southeastern
university.
Quantitative study with a cross-sectional design.
Employed all web-based questionnaires including
(via email invitation); 16-item survey on workplace
environs, the Nature Contact Questionnaire (NCQ),
The Perceived Stress Questionnaire (PSQ) and 13-
item health behavior assessed dependent variables
and health outcomes. web-based survey design.
PP
Significant, negative association
b
etween nature contact and stress
and nature contact and general
health complaints. The results
indicate that as workday nature
contact increased, perceived stress
and generalized health complaints
decreased.
Takayam
a [49] Japan
Participants were recruited
from four prefectures in Japan.
All participants were male
N = 45; Adult males aged 19–
22 years.
Forested and urban sites (8
total)), were used in this study.
All sites located in, or near to
the towns of Yoshino, Akiota
To test the beneficial health effects of walking in
forests against urban environs in 45 total
respondents. Four nature walking sites and an urban
control were used as the field sites. This quantitative
Hypothesis was supported—in
that- compared with the urban
control, overall psychological well-
b
eing improved more in forest
Int. J. Environ. Res. Public Health 2017, 14, 851 20 of 37
university students deemed
healthy at the time of the study.
and Kamiichi and the city of
Oita, Japan.
study included the following psychological
assessment tools: Profile of Mood States (POMS)
indexes, Restorative Outcome Scale (ROS) and
Subjective Vitality Scale (SVS).
PP
environments. Subjects noted that
the forest walking program
induced feelings of relief and
revitalization, whereas the urban
walks did not.
Kang [50] Korea
Participants for this study were
recruited from the Department
of Rehabilitation Medicine of
Hanyang University Medical
Center, where they were being
treated with posterior neck pain
for a period of 3 months or
greater.
N = 64; 11 males and 53
females.
Experimental trials took place
at the Department of
Rehabilitation Medicine of
Hanyang University Medical
Center and undisclosed nearby
forested area.
To compare the pain-reducing effect of FB alone vs.
FB in combination with stretching and strengthening
exercises in patients with chronic posterior neck
pain. Participants were randomly divided into FB
Alone (FBA: n = 32) and FB Exercise (FBE: n = 32).
The Visual Analog Scale, neck disability index (NDI),
Euro-Qual 5D-3L VAS (EQ VAS) and index (EQ
index). McGill pain questionnaire (MPQ), number of
trigger points in posterior neck region (TRPs) and
ROM of cervical spine were evaluated on the first
and last day of the program and compared between
groups.
PP
The number of TRPs were
significantly reduced in the FBE
group compared with the FBA
group (p = 0.013). The other scales
used showed no difference.
Hawker
[51] Visual Analog Scale reliability
and validity NA NA
Measures of adult pain: Visual Analog Scale for Pain
(VAS Pain), Numeric Rating Scale for Pain (NRS
Pain), McGill Pain Questionnaire (MPQ), Short-Form
McGill Pain Questionnaire (SF-MPQ), Chronic Pain
Grade Scale (CPGS), Short Form-36 Bodily Pain Scale
(SF-36 BPS), and Measure of Intermittent and
Constant Osteoarthritis Pain (ICOAP)
NA
Beil [52] USA Participants included residents
of Portland, Oregon.
N = 15; 15 (8 males, 7
female), aged 20–61 years
with an average age of 42.3.
Urban and natural outdoor
settings (4 total) within 15 km
of research lab.
Quantitative, randomized controlled trial with pre-
and post-test design. Participants were exposed to
urban and natural forested environmental settings
respectively for 20 min at a time. Salivary amylase
and subjective measures of stress were taken before
and after each exposure. Testing methods included
web-based survey analyses via the Subjective Stress
Scale (Stress), Environmental Identity (EID) Scale
Perceived Stress Scale (PSS) Perceived
Restrictiveness Scale (PRS) [post-test only], Saliva
(sCort and sAA).
PP
Participants experienced less
physiological & psychological
stress from exposure to the natural
environments versus built
environs as measured by pre- and
post-intervention changes in
salivary amylase and self-reported
stress. The greatest decrease in
stress was noted in females in
natural settings.
Kobayash
i [53] Japan
The study consisted of 625 male
J
apanese students at the
University of Chiba, Japan,
N = 625; Males with a mean
age of 21.6 years +/1.6 years.
Forested areas (57), and urban
areas (57) within Japan.
To expose Japanese students at the Chiba University
to urban and forest environments respectively—in
order to ascertain relevant effects on autonomic
Demonstrated a roughly 80%
increase in the parasympathetic
indicators of HRV with a decrease
Int. J. Environ. Res. Public Health 2017, 14, 851 21 of 37
deemed healthy at the time of
the study.
nervous system function. This quantitative RCT
included 57 Forest and 57 Urban sites selected across
J
apan. Participants sat for 15 min while viewing
either setting. Measures included HRV, which was
monitored continuously. The experiment was
performed over 2 consecutive days at each site.
Measures of HRV were conducted between 13:30
and 15:30 for 15 min at a time. These were RCTs; one
group was exposed to the forest site prior to the
urban site & vice versa.
PP
in sympathetic indicators of
HRV—physiologically
demonstrating that forest-viewing
was more effective in reducing
indicators of stress than the urban
areas.
Engert
[54] Supporting material NA NA
Investigation into the cross-correlation of salivary
cortisol and alpha-amylase responses to
psychological stress.
NA
Fisher
[55] Supporting material NA NA A Conversation with David Milarch NA
Igarashi
[56] Japan
Students (male and female),
from the Chiba Prefectural
Kashiwanoha Senior School,
deemed in good health prior to
the orientation of the study.
N = 48; 19 high school males
mean age 16.2 ± 0.7 years,
and 21 high school females
mean age 16.6 ± 0.9 years.
Chiba Prefectural Kashiwanoha
Senior High School lab rooms.
Clarification on the physiological and psychological
effects on HS students viewing real vs. artificial
pansies. Participants were exposed to yellow fresh
pansies for 3 min each. Artificial pansies in a planter
were used as a control. Heart rate variability (HRV)
was tested.
SM
Exposure to real pansies increased
the activity of the Parasympathetic
Nervous System (PNS). Viewing
real flowers resulted in
comfortable relaxed and natural
feelings. Visual stimulation with
real flowers induced psychological
relaxation effects HS students
Tsutsumi
[57] Japan
Participants included young
male Japanese adults deemed
healthy at the time of study.
N = 12; Males, with a mean
age of 22.2 ± 1.7 years.
Studies completed in
laboratory settings at the
research center.
To determine whether stimulation by viewing an
individual preferred video of sea or forest has an
effect on relaxation. Participants were divided into
two groups based on their preference for sea or
forest scenery. By using a visual analog scale the
participants watched 90 min. DVDs of the sea with
natural sounds and forest with natural sounds while
HR variability and Bispectral Index System value
were measured using MemCalc/Tawara and
Bispectral Index System monitor.
SM
Decreased HR, increase in high
frequency and sustained arousal
level were observed while viewing
the preferred video. The viewing
of the preferred video had a
positive relaxation effect.
Individual preferences should be
honored when initiating video
relaxation therapy.
Park [58] Supporting material NA NA
The physiological effects of Shinrin-yoku (taking in
the forest atmosphere or forest bathing): Evidence
from field experiments in 24 forests across Japan.
NA
Logan
[59] USA Supporting material NA NA Literature review is based upon 30 years of available
research demonstrating the potential healing
Research culled demonstrated that
“nature” exposure is beneficial to
Int. J. Environ. Res. Public Health 2017, 14, 851 22 of 37
properties of nature on mental and physical well-
b
eing under the premise of nature’s healing power
coined by Sir. J. Arthur Thomson. The authors
propose a philosophical and psychological
framework from which to conceive of the potential
for forest-therapy and forest-bathing programs
F
the mind in terms of relaxation and
feelings of connectedness - as are
viewed by the tenets of this paper
to be “beneficial.”
Selhub
[60] Supporting material NA NA The Science of Nature’s Influence on Your Health NA
Berger
[61] USA Supporting material NA NA
Describes a creative framework in which nature is
incorporated into therapy with older adults. Using a
practical example, this study illustrated how the
integration of concepts from a narrative approach
and the innovative nature-therapy framework could
aid a geriatric population in expanding personal
perspectives, strengths, and coping strategies, while
gaining a wider sense of acceptance and completion
in life.
F
This framework highlighted a way
in which the connection between
the personal story and the natural,
cosmic story could enhance the
participants’ sense of completion
within themselves and their
surroundings, which may be
further implemented into holistic
nursing.
Zdravkov
ic [62] Supporting material NA NA Nature and forest therapy workshops offered online. NA
Poulsen
[63] Denmark
The population addressed were
soldiers and veterans from the
Danish military rehabilitation
unit who had served in war and
were diagnosed with some
degree of Post-Traumatic Stress
Disorder.
N = 8; Males aged 26–47
years.
University of Copenhagen
forest therapy garden
“Nacadia,” which is located in
Hørsholm arboretum. .
Qualitative study employed a phenomenological
approach in an effort to understand and elucidate
the effects of Nature-Based Therapy (NBT), on the
well-being of the subjects. The design of the study
was based on a previous case study from China
addressing similar questions. In this study the
participants PTSD is the concern, the context is the
forest therapy garden and the phenomenon is the
participant’s experience of NBT from 10 consecutive
weeks of treatment. Interviews were conducted at
four stages of the program.
PP
Researchers generated three key
themes from analysis of the
interviews. These included: taking
nature in, Nature-Based
association as an initiation to
therapeutic processes, and nature
seen as a part of everyday life.
Participants reported a sense of
refuge, safety, calmness, and
general wellbeing.
Beck [64] Supporting material NA NA Perceived level and sources of stress in baccalaureate
nursing students. NA
Reeve
[65] Supporting material NA NA Perceived stress and social support in undergraduate
nursing students’ educational experiences. NA
Kreitzer
[66] Supporting material NA NA Integrative nursing: Application of principles across
clinical settings. NA
Int. J. Environ. Res. Public Health 2017, 14, 851 23 of 37
Watson
[67] Supporting material NA NA The core concepts of Jean Watson’s Theory of
Human Caring and Caring Science. NA
Olsson
[68] Sweden
Population criteria included
males and females from a
region in Sweden diagnosed
with early-stage dementia of
various ages, who were able to
speak. Sampling included
persons who had an expressed
desire to be alone outdoors and
were living at home.
N = 11; Aged between 52 to
81 years, 5 women and 6
men.
Interviews in this study took
place in the participant’s
homes; indoors and outdoors at
the homes.
Qualitative interview based study was to determine
and report on how persons diagnosed with dementia
reflect on what it’s like for them when experience an
outdoor setting. Purposive sampling was used to
obtain this cohort. As part of a larger study focusing
on dementia, qualitative content analysis was used
to categorize the interview results into core themes
b
ased upon interviewee’s experiences and
discussion.
PP
Results of these interviews
reflected that subjects unanimously
experiences a sense of well-being
and self-worth regarding
independent outdoor activity.
Furthermore, interviewees
reported the outdoor setting as
complementary to a sense of well-
b
eing. Potential challenges and
adaptive strategies were addressed
when navigating outdoor settings.
Song [69] Japan
Middle-age hypertensive men,
that had never taken medication
for HTN, HLD, or DM
N = 20; Male (100%, )mean
age 58.0 ± 10.6 years
Akasawa natural recreation
forest near the Agematsu town
of Nagano Prefecture
To determine the effects of FB on the autonomic
nervous system. Participants were asked to sit in
b
oth urban and forest areas for 10 min in each
location and Heart Rate were both measured.
Questionnaires were also given to participants to
collect data on emotional condition while viewing
b
oth settings.
PP
HF HRV was increased while
viewing a forest landscape, while
heart rate was decreased in
comparison to the urban setting
viewings. Additionally,
participants felt more
“comfortable,” “relaxed,” and
“natural” after viewing the forest.
Berger
[70] USA Supporting material N/A N/A
Proposed an application of NT for the treatment of
emotional and psychiatric issues. This expository
piece provided a framework based upon previous
applications of NT in two anecdotal examples from
Israel: “The Healing Sand” and “The Enchanting
Forest.”
F
The innovative approach offered in
this article was supported by
b
ackground research in relevant
expressive arts therapies. It
inferred that NT enables persons to
feel relief from stress in addition to
increased social conscientiousness.
Berger
[71] Israel
The population at the center of
this study included students in
the elementary classroom of
Galim as well as their
homeroom teacher and
therapist.
N = 13; 9 boys and 2 girls
aged 7–9, 2 female adults
aged 42 and 33, respectively.
Galim elementary school
(Israel) for children with
learning and behavioral
disabilities.
Expositional case study, rooted in grounded theory
analysis, qualitatively analyzed the utilization of the
NT framework for children with learning and
b
ehavioral disabilities. Subjects engaged in a NT
program for 1 year. Interviews and questionnaires
provided data based upon analysis of the
framework’s role in education and scholastic
development.
PP
This study demonstrated a
successful protocol and application
for nature -oriented therapeutic
activities in a classroom setting for
study population and described
how NT can enhance, or support
pre-existing modalities for
students with learning disabilities.
Berger
[72] USA Supporting material N/A N/A
NT created theories and models to assist the
therapist working in nature to create a
therapeutically appealing setting. From a
This framework showcased
concepts from eco-psychology,
drama and ritual.
Int. J. Environ. Res. Public Health 2017, 14, 851 24 of 37
psychological, eco-social perspective, the author
surmised that strengthening a relationship with
nature may reduce depression and anxiety and
foster emotional continuity, happiness and wonder.
The purpose of this book chapter (#2) was to
illustrate a framework for NT as a creative
therapeutic discipline via active research and
reflexive process for the author’s PhD.
F
Key: PP: Psychological & Physiological. SM: Sense Metrics. F: Frameworks.
Int. J. Environ. Res. Public Health 2017, 14, 851 23 of 37
The trends revealed by SY research over the past 10 years in relation to the cardiovascular and
autonomic nervous systems (ANS) appears to have started with basic cardiac monitoring then shifted
to the correlation of cardiac monitored data points with the PNS and SNS, and this started the
development of a more in-depth study design to research the effects of SY on specific disease states,
such as: hypertension (HTN), coronary artery disease (CAD), and chronic obstructive pulmonary
disease (COPD).
According to Kobayashi, Song, Ikei, Song, Kagawa and Miyazaki [18], 625 Japanese males
situated in 57 forest-sites and 57 urban-sites across Japan revealed an 80% increase in the
parasympathetic indicators of HRV while experiencing the forest setting—physiologically
demonstrating forest-viewing was more effective in reducing indicators of stress than in the urban
participants. The methods and findings of this large sample study are grounded in some of the earlier
pilot studies culled for this review. In Park et al. [37] quantitative study, the sample size was limited
to 12 males; however, it was one of the earliest studies to interpret the R-R intervals of the
electrocardiogram analyzing pulse rate, in addition to SBP/DBP and LF/HF) components of HRV.
This study design [37] has been echoed throughout multiple studies which limit physical activity
levels to 20-min for each activity researched in order to control for the cardiovascular effects of
physical exertion on each participant [19,22,27,38–41].
Blood pressure and PR also decreased while in the forest settings compared to the urban settings.
In comparison to physical exercise tasks, Lee, Lee, Park and Miyazaki [20] measured HR and BP in
relation to synthetic versus organic stimulation. This study revealed both HR and BP decreased in
participants after they had completed a garden transplanting task compared with participants’ HR
and BP gradual increase throughout a computer performance task. Similar to the findings of
Tsunetsugu et al. [40] consisting of 12 males, a study of 17 females over the age of 40 by Ochiai et al.
[25] revealed an overall decrease in HR after one day of a “forest-therapy program”. These studies
demonstrate cardiovascular benefits for both genders. After controlling for both demographic and
socioeconomic factors, Kardan et al. [42] conducted a correlation analyses of data acquired through
the Canadian Ontario Health Study. High resolution satellite imagery suggests residents of
neighborhoods with a higher density of trees on the streets report less ill cardio-metabolic conditions
than do residents of neighborhoods with less trees. Thematically, it is evident the cardiovascular (CV)
benefits of SY are apparent regardless of age, gender, socioeconomic background, or previous
exposure to a nature setting.
3.3. Physiological Disease States
Significant research has revealed the effects of SY and NT on specific physiological disease states,
including HTN, CAD, COPD, and Diabetes Mellitus Type II (DMII). In a randomized control trial
(RCT) of 24 adults with HTN, Mao et al. [29] found throughout a week-long trip to a nature setting,
BP indicators, and CV disease-related pathological factors decreased the activation of the renin-
angiotensin system, therefore reducing the workload of the heart and helping to manage the
symptoms of HTN. In a RCT of 20 Lithuanian adult patients with CAD, Grazuleviciene et al. [43]
found after a week of 30-min sessions in nature, the participants’ cardiac function improved overall.
This is a groundbreaking study in there has never been a study prior to their publication that
addressed “cardiovascular relaxation and recovery of homeostasis in CAD patients.” Jia et al. [44]
found a decrease of perforin and granzyme B expressions accompanied by decreased levels of pro-
inflammatory cytokines and stress hormones in 20 patients diagnosed with COPD indicating some
of the potential health benefits of SY for individuals living with COPD. Furthermore, in a longitudinal
study of 48 adults diagnosed with DMII, Ohtsuka [45] found blood glucose readings declined after
multiple SY practice sessions, therefore indicating a significant correlation between SY and the
reduction of blood glucose levels. This study is one of the few measuring the effects of SY over time,
which indicates further research may be conducted to confirm the long-term effects of SY, not only
for its effects on patients with DMII, but for patients with different disease states as well [23,29,43–45].
Int. J. Environ. Res. Public Health 2017, 14, 851 24 of 37
3.4. Psychological
Morita et al. [46] noted while SY has been popularized in Japan given the ease of access to
forested environments and its’ conscientious governmental recommendations, individuals globally
have reduced acute psychological distress from time spent in greenspace (Figure 3).
Figure 3. Walking in nature. Permission to publish from CiCi Lee.
Furthermore, Morita et al. [46] investigated SY’s effect on 498 Japanese residents suffering from
acute and chronic stress. Of these research participants, those suffering from chronic stress states
reported the greatest reduction in subjective feelings of hostility, depression and anxiety as a direct
result of time spent in the forested environs. Additionally, a RCT reflecting this practice, Sung et al.
[47] developed a Cognitive Behavioral Therapy (CBT) based on a FT program, which included
educational sessions and guided FB activities for middle-aged men and women diagnosed with Stage
I HTN in South Korea. The CBT FT program incorporated elements of meditation and relaxation
techniques in chosen forested environments, as well as participant self-reflection and goal setting
[47]. The results of which demonstrated a significant decrease in the salivary cortisol (tested as a
biomarker of stress), increase in Quality of Life (via the QoL questionnaire) and a decrease in anxiety.
However, this study also gleaned a transient effect in the reduction of individual’s manual self-
reported BP measures. Self-reported manual BP reports are subject to reliability issues of
measurement and bias. Moreover, the lack of additional objective analysis in the short-term forest-
environment exposure are identified confounding variables, as well as the fact the participants took
prescribed antihypertensive medications throughout the trials in the intervention and control groups
respectively [47].
A hallmark of SY research has been the investigation of its’ relaxation inducing properties and
application for ameliorating psychological distress. Within this review, 12 studies specifically
addressed psychological disorders/disease states and relevant comorbid conditions with popular
reference to stress and stress related heart disease, emotional distress and chronic depression,
alcoholism, sleep disorders, and pain [5,6,26,30–33,47–51]. Takayama et al. [49] noted the impetus for
their SY research stemmed from a growing concern for overworked urban dwellers’ chronic stressors.
The results of this comparative study, while limited by sampling bias regarding the subject
population consisting entirely of males, indicated a unanimous preference for forest walks versus
urban walks based upon data synthesized from participants’ responses to the Profile of Mood States
(POMS), Restorative Outcome Scale (ROS) and Subjective Vitality Scale (SVS) pre- and post-intervention.
Stress from urban environments caused by surmounting noise and environmental pollution,
commuter traffic, financial expenses, increasing tasks, and lack of proximity to FB environs/attributes
Int. J. Environ. Res. Public Health 2017, 14, 851 25 of 37
motivated Park et al. [26] to investigate the connection between psychological distress and
greenspace accessibility. This study which included a large, single-sex sample of 168 males between
the ages of to 20 to 24 years of age, demonstrated subjects’ preferences for forested environments,
specifically in relation to temperature, as demonstrated by participants’ reported lower Predicted
Percentage Dissatisfied (PPD) scores related to summer climes within forested environs compared
with higher air temperature and heat indexes in urban environments [26].
Citing the impact of chronic stress on growing populations with insomnia and poor sleep
patterns in Japan, Morita et al. [32] studied forest-walking to induce relaxation and improve general
sleep-wake cycles in a population of 71 men and women over the course of three months. Participants
reported a statistically significant correlation between increased sleep time (from an average of
365.9 ± 89.4 min to 419.8 ± 128.7 min) post 2-h afternoon forest walks with decreased anxiety.
McCaffrey, Hansen and McCaffrey [30] investigated garden walking to reduce severity of signs
and symptoms of depression in older adults. Participants’ personal stories citing the emotionally
healing attributes of the natural surroundings and garden walking paths at the Morikami Japanese
Museum and Gardens in Delray Beach Florida, USA inspired the aforementioned researchers.
Similarly, Kim, Lim, Chung and Woo [31] investigated the application of a 4-week forest-walking
based CBT program for treating clinical depression. Research findings from Kim et al. [31]
demonstrated a significant remission rate in the forest walking group at 61% over the traditional
psychotherapy hospital-based group at 21%. Kim et al. [31] explicitly cited the work of Australian
bush adventure therapy researchers Pryor, Carpenter and Townsend [52] in their pioneering work
regarding the connection between time spent in nature and an increase in participants’ health, well-
being and emotional confidence. Kim et al. [31] employed a robust research design in so much as
researchers incorporated the comparisons of a forest-walking based CBT program (N = 23), a hospital
based treatment group (N = 19) and an outpatient control (N = 21). Yet, as with the Pryor et al. [52]
research, inherent to the research aim of investigating the previous successes of nature-based therapy
[31] is an implicit bias toward the functionality and reliable successes of the research outcomes.
Given SY practices are relatively innocuous when compared with other more invasive
procedures, Chun, Chang and Lee [2] studied FT for patients (N = 59) diagnosed with depression and
anxiety (roughly 60–80% of the participants), as well as oxidative stress (roughly 30–50% the
participants) that is associated with stroke susceptibility and a positive stroke history. The results of
this study, indicated the Beck Depression Inventory (BDI), Hamilton Depression Rating Scale (HAM-
D17) and Spielberger State-Trait Anxiety Inventory (STAI) indicate scores were lowered in the post
FT intervention group when compared with the control group scores. These results led researchers
to recommend FT as a medically viable intervention for the psychological distress associated with
chronic illness [2]. Since its’ inception in the 1970s, the STAI has been a hallmark test used to
differentiate between participants’ state and trait anxiety, however, its’ brevity and pre-supposed
delineation between anxiety-oriented temperaments inspires cause for concern over its’ reliability [53].
Han et al. [3] and Kang et al. [50] focused on chronic widespread pain (CWP) and localized pain
in relation to the emotional distresses of coping with the side-effects of intractable pain. In Han et al.
[3] psychological indices were measured pre- and post- FT intervention with the BDI and the Visual
Analog Scale (VAS) to measure intensity and frequency of CWP. The results revealed statistically
significant decreases in pain and associated psychological distress as per the psychometric scales.
Whereas, Kang et al. [50] utilized the VAS and the neck disability index (NDI) for chronic neck pain
and the McGill pain questionnaire (MPQ) for localized pain, among other measures for physiological
indices. Kang et al. [50] measured incidents of painful trigger points in the posterior neck region
(TRPs) in the FB with exercise group compared with the FB without exercise, which resulted in
reduction by nearly ½ of TRPs in the FB plus exercise group. Widely utilized as a metric for measuring
pain, Kang et al. [50] noted the test’s functional role in objectively evaluating participants’ subjective
experiences of pain. Researchers noted the popularity of the VAS [51], but further investigation was
warranted to determine its’ reliability and validity. The VAS does have a reported test-retest
reliability among patients experiencing chronic pain (r = 0.94; p < 0.001) in a previous investigation
Int. J. Environ. Res. Public Health 2017, 14, 851 26 of 37
[51], yet, given the subjective nature of pain and uncertain unanimous consensus on pain metrics in
international medical literature, this study demonstrated a lack of criterion validity for the VAS.
With regards to human spirituality, Nakau et al. [33] noted in their pilot study involving 22
breast or lung cancer patients, consisting of 4 males (with an average age of 65.3 ± 2.6 years) and 18
females (with an average age of 56.6 ± 11.3 years), that FT can be viewed as an enhancement of
spiritual health in cancer patients. Patients in this study [33] were all participating one month or more
after undergoing surgery, chemotherapy, or radiation treatment. While patients were not considered
to be at risk of life-threatening conditions at the time of study [33], the stress of undergoing treatment
for chronic disease was implicated. All patients (N = 22), participated in the integrated FT,
horticultural therapy, yoga exercise, meditation and group therapy treatment intervention at the
Japan World Exposition (1970) Park in Suita, Osaka prefecture, Japan [33]. The results of this study
indicated statistically significant correlations pre- and post-intervention between green environments
and individuals’ experiences of self-realization, increased emotional health and integrative well-
being, as measured by the Japanese version of the Functional Assessment of Chronic Illness Therapy-
Spiritual Well-Being Scale (FACIT-Sp), QoL questionnaire, Cancer Fatigue Scale, POMS and STAI, in
addition to physiologic measures of NK activity [33].
3.5. Autonomic Nervous System Effects
Research on the cardiovascular effects of SY have precipitated a trend to discover how FB affects
the ANS. At the level of the central nervous system (CNS) alone, marked changes in cerebral activity
have been identified. Joung et al. [28] designed novel research to investigate identified specific
anatomical cortices within the brain that vary in stimulation to both forest and urban areas. Activity
in the prefrontal cortices of the forest-area group participants were significantly lower than that of
the city-area group participants in the “after walking” through their randomly assigned locations.
This decrease in activity suggests a strong correlation between nature settings and ANS activity [28].
Research has shown peak HF levels can be seen within 5–7 min of each nature experience, which
demonstrates not only will SY benefit the health of the ANS, but that positive HF components of HRV
are evident within minutes of forest immersion [9]. Regarding other physiologic indicators of stress,
Mao et al. [24] conducted a quantitative RCT that demonstrated after short periods of time in nature,
measures of malondialdehyde (MDA) concentrations, cytokine production, serum cortisol, testosterone,
and lymphocytes decreased. Universal findings revealed LF components were significantly lower in
the forest areas than in the city areas, while HF components of HRV tended to be higher in the forest
than in the city and therefore these research findings are important for further physiological research
and the effects of SY [17,18,20,23–25,27,52].
3.6. Endocrine Function
This section, a further investigation into the physiological and psychological effects of SY or NT
via the physiological metrics relevant to endocrine included 11 publications. These resources
specifically measured the effects of SY or NT on specific physiological and psychological indicators
of stress via measures of salivary cortisol (sCort), and/or emotional indicators of health and well-
being [1,17,24–27,34,36,40,47–49,52,53]. Kobayashi and Miyazaki [53] studied baseline cortisol
measures in 267 healthy male students from The University of Chiba, Japan, with the aim to compare
measures in future SY studies. In Largo-Wright et al. [48] researchers deduced a correlation between
increased contact with nature and decreased stress levels and generalized health complaints in office
workers at a Southeastern university in the U.S. via the Nature Contact Questionnaire (NCQ), The
Perceived Stress Questionnaire (PSQ), and a health behavior assessment derived from contact with
the outdoors, over other types of contact with nature, such as indoor plants [48]. Additionally,
practices of SY have demonstrated statistical significance in lowering blood-glucose. In a 2012
longitudinal trial, researchers from Hokkaido University, Japan, demonstrated forest-walking
reduced blood glucose levels in 48 Type 2 diabetic patients [34]. A total of 48 participants, 16 males
and 32 females, with a mean age of 66.8 years and diagnosed with DMII, walked for distances of 3 to
6 km nine times per week over a period of 6 years. There was no statistically significant difference
Int. J. Environ. Res. Public Health 2017, 14, 851 27 of 37
between the subjects’ glucose levels, or HbA1c levels between the shorter and longer walks.
However, averages of both groups’ blood glucose levels pre and post-forest walks declined by 79 ±
10 mg/dL and 76 ± 7 mg/dL respectively [34].
In the pilot study with a cross-over experimental design, investigators [52] addressed the impact
of participants (N = 15) exposure to four urban and natural environments on physiological and
psychological stress matrices. The study [52] utilized sCort and salivary amylase (sAA) as metrics,
which the authors note via the work of Engert et al. [54] have been significantly reliable physiological
biomarkers for stress. Additionally, Beil and Hanes [52] obtained data from questionnaires measuring
participants’ experience of stress via the Perceived Stress Scale (PSS), Perceived Restorativeness Scale
(PRS), Subjective Stress Scale (SSS) and susceptibility of affective connections to natural environments
via the Environmental Identity Scale (EID), pre- and post-intervention, which included a 20-min
exposure to 4 different environments ranging from the “mostly built” to the “mostly natural.” The
participants’ sAA and sCort levels respectively peaked after exposure to the urban environments,
while levels were within normal range post exposure to the natural environments, which also
correlated with participants’ subjective impressions of stress [52]. The EID, while relatively novel,
was noted to have been previously tested for its’ effectiveness in ascertaining subjects’ general health
and welfare status in response to the environment [52].
3.7. Sensory Metrics (SM)
Fisher [55] illuminated an emerging interest in FT practices for psychological and physiological
healing. By interviewing a proponent of FT, Fisher described the growing trend of individuals
restoring native tree habitats with the dual purpose of environmental stewardship and psychological
welfare of the persons involved in the process; paralleling the sentiments of many SY researchers [9]
and supporting the Biophilia hypothesis [8]. Furthermore, Stigsdotter [36] conducted a case-study
that followed up on survey driven data collected from a 2005 Danish Health Interview of 10,125 adult
males and females and, results revealed significant positive correlations between access to green-
space within 1 km, self-perceptions of stress and general health and well-being.
A subset of publications explicitly focused on sensorial stimuli, as a function of the effects of SY,
which included time spent in forested outdoor environments, interactions with elemental aspects of
natural environments and laboratory settings. Tsunetsugu et al. [13] synthesized evidence from
physiological and psychological indices into subcategories, which exemplified the biomechanics of
SY impact on the five senses. Eight key publications specific to SM were incorporated within this
review, including: the metrics of olfaction [14,16], tactile stimulation [19], and visual stimulation, or
neurological response [11,15,28,56,57].
Research included within the SM theme invariably measured nervous system activity and
emotional response of participants in relation to experiencing authentic aspects of forested
environments by comparative means. Igarashi et al. [56] studied participants’ HRV, as an indicator
of PNS activity in 48 high-school students viewing real vs. artificial pansies, the results of which
illustrated a stronger correlation between relaxation with the real pansies versus the silk flowers. This
was represented by a significant decrease in the ratio of LF/HF HRV, and subjective analysis of
students’ self-perception of relaxation indicating preference towards real flowers. Furthermore,
Igarashi et al. [11] analyzed right and left prefrontal cortical activity in terms of cerebral blood-flow,
and hemoglobin concentration changes via Near Infrared Time Resolved Spectroscopy (NIRS), which
was measured in units of micro-meters (µM), according to the wavelengths observed. This was
performed before and after participants were subjected to four visual conditions (real dracaena
plants, images of dracaena plants, cardboard boxes and images of cardboard boxes) for timed
intervals of 0–3 min each. Notably, µM concentrations were higher in participants viewing the actual
dracaena plant stimulus for 3 min versus the pictorial sample for the same amount of time in right
and left prefrontal cortical areas respectively [11]. Joung et al. [28] also utilized NIRS to determine
µM levels pre-posttest upon participants viewing actual forested versus urban areas. Counter to the
aforementioned Igarashi et al. [11] study, participants demonstrated increased subjective measurements
of relaxation correlated with decreased µM concentrations and prefrontal cortical activity, and
Int. J. Environ. Res. Public Health 2017, 14, 851 28 of 37
increased feelings of calmness from the forested site vs. urban site [28]. This may indicate not only
are aspects of the natural environment optically stimulating as illustrated by Igarashi et al. [11] but
they may also require less executive functioning as demonstrated by Joung et al. [28]. Mutual feelings
of “calmness” were derived from each study.
Igarashi et al. [15] looked at comparisons between participants viewing images of kiwifruit
orchards and specific urban areas in Japan. The POMS and HRV were used to evaluate participants’
responses, which demonstrated moderate increases in PNS activity and feelings of “relaxation and
calmness” when viewing the orchard versus an urban setting. Subjective measures of stress reduction
have been consistently apparent in the studies focused on visual stimulation regardless of physiological
indices. In Tsutsumi et al. [57], researchers aimed to investigate and compare participants’ relaxation
states before and after viewing visual footage of forested landscapes, and comparatively, seascapes.
Measures of HRV, results from POMS questionnaires, and Bispectral Index System analysis
(measured brain activity via electrode placement) allowed researchers to determine participants’
sleep-wake states while comparing brain wave activity. Findings indicated significant decreases in
HR, greater relaxation in post-intervention analysis in both groups, with the forest-viewing group
demonstrating the greatest difference in relaxation-states across all measures [57]. These studies give
statistically significant credence to the notion visual stimulation by aspects of forested environments
reduces stress and increases a general sense of well-being in various study populations. Furthermore,
these studies serve as templates to be integrated into therapeutic practices as suggested by
Tsutsumi, et al. [57].
Koga and Iwasaki [19] investigated the potential for foliage-based tactile stimuli to induce
relaxing effects that have been demonstrated via SY based field experiments. These researchers [19]
utilized NIRS to detect cerebral blood-flow and the Semantic Differential (SD) model to determine
emotional responses in participants’ experiences with touching leaves versus other non-natural
substances, such as plates of metal and fabrics. As noted by Park et al. [58], laboratory-based research
on the physiological and psychological effects of SY has been paramount. Furthermore, the Koga and
Iwasaki [19] study revealed statistically significant correlations between touching natural substances,
such as tree-bark, and incidents of decreased blood pressure. Moreover, these findings are associated
with an increase in participants’ subjective feelings of calmness. However, despite the clarity in
exposition, researchers didn’t identify the reliability and validity of the SD method utilized in the
study. As with several SY studies, specific to psychological indices, self-reported measures in the
form of questionnaires, such as the SD method, provided a bulk of the data. Therefore, leaving a
question about the consistency, validity and reliability of the reported psychological outcomes.
Previous research regarding the effects of SY explored elements of olfaction as a sense metric
relevant to the biological effects of experiencing forested environments. Tsunetsugu et al. [13] noted
in their review, phytoncides, or volatile organic chemical compounds released from plants and trees
have previously been associated with the effects of SY. Furthermore, Li et al. [63] described how the
scent derived from phytoncides of 13 different tree species (phytoncides are unique to each specie
and serve as a critical communication pathway between trees classified under the same genus)
increased human Natural Killer Cell activity and decreased adrenaline in the FT intervention group
of the study comparing urban and forested environments on human immune and stress function.
Ikei et al. [16] studied the impact of α-pinene, a phytoncide from Japanese cedar wood (which is
notably ubiquitous in forested areas of Japan) on ANS function via HRV indexes and the SD method.
The results of which indicated an increase in PNS activity and a decrease in heart rate [16].
Jo et al. [14] focused research efforts on “floral scent”, specifically Japanese plum blossoms,
utilizing NIRS, HRV, POMS, and the SD as the physiological and psychological indices. Researchers
created a unique apparatus for metering the floral and control scents, which involved a polypropylene
pressurized bag with a constant flow of controlled air to be inhaled by participants. This novel
approach controlled for many potential confounding factors given the ubiquity of various scents in
laboratory settings. Utilizing multichannel NIRS enabled researchers to investigate the effects of
olfactory stimulation on 47 localized neurological regions corresponding to areas noted for emotional,
judgement, motor control, memory, somatosensory, cognitive, visual, auditory, and speech functions
Int. J. Environ. Res. Public Health 2017, 14, 851 29 of 37
[14]. The literature expounding upon sense-metrics pertaining to the effects of SY illuminates a
thorough pursuit of specificity and ingenuity.
Following a systematic review of 25 articles from databases including, but not limited to
PubMed, EMBASE, CINAHL, and PsychINFO, Bowler [1] found each study suggested natural
environments may have direct and positive impacts on humans’ overall well-being. Bowler
recognizes it is difficult to truly separate the raw effects of experiencing nature from confounding
factors, such as physical activity performed, previous exposure to nature, as well as an optimal time
frame for these effects. However, Bowler and every author mentioned throughout this literature
review stress the aim to encourage research on the health benefits associated with the practice of SY.
While research in primarily Japan and China has shown a positive impact of SY on both the
physiological and psychological structures throughout the human body, it also calls for Western
cultures to incorporate elements of the SY practice, so as to demonstrate compatible results world-
wide for both patients and their healthcare providers [1].
3.8. Conceptual Frameworks
3.8.1. Nature Therapy
During the review of the literature, existing conceptual frameworks emerged that may be
applied to SY practice and NT research. The first conceptual framework (CF) is Thomson’s “vis
medicatrix naturae,” otherwise known as, “the innate ability of the body to heal itself” as presented
in Logan and Selhub’s review of the effects nature has on the human brain [59]. Thomson posits the
healing power associated with nature is directly connected with an individual’s intentional contact
with “animate and inanimate” aspects of the outdoors, such as touching the bark of a tree. While
recognizing today’s citizens’ increased use of technology, exposure to air pollution and the associated
increased stress responses, Logan and Selhub [60] present questions based on Thomson’s framework.
For example, “What might be an appropriate “dose” (duration and frequency) of nature contact to
reduce stress?” “Are certain types of activities (e.g., gardening, walking in forest settings,
contemplating in an urban park) more effective than others?” [60] Future directions for research,
global urban planning and architecture, and policy making may be based on Thomson’s framework
of “vis medicatrix naturae.” Furthermore, the research conducted by Selhub and Logan directly
points to the health benefits associated with natural environments and may be parallel to the practice
of SY and NT.
3.8.2. Psychological Underpinnings
The second CF is by Berger [61]. Berger presents a novel, autonomous and independent NT
framework that serves as a model to support art and drama therapy. Within this theoretical and
applied framework, which is considered “integrative” because it takes place in nature and serves as
a part of the human healing process is the self- “reflexive” process that includes personal experiences.
The NT model and theory are supported by past evidence derived from Gestalt psychology and the
narrative research approach mixed with traditional “ritual” foundations. This novel theory attempts
to put a spotlight on modern individuals detachment from nature, absence from community
engagement and spirituality through a psycho-eco-social lens. Berger purports individual’s personal
estrangement from nature, lack of involvement in community affairs and spirituality as being main
factors influencing the modern-day spread of loneliness, depression, anxiety, low self-esteem and
detachment. SY practice and NT research may be grounded in Berger’s CF that recognizes the healing
natural forces, resilience and recovery associated with nature.
The third CF is from a Threshold Concept and Transformational Learning perspective [62]. The
practice of SY assisted by trained nature and forest therapy guides leads individuals into a “liminal”
space. In this “liminal” space, also known as an “in-between” human state or “suspended state of
partial knowing,” the healing properties associated with SY are purportedly activated [62]. During
the “liminal” phase, a person integrates, discards and experiences an “ontological shift” and then
experiences “transformation” and a “changed discourse,” known as a “post-liminal phase.” The
Int. J. Environ. Res. Public Health 2017, 14, 851 30 of 37
individual may experience a “pre-liminal” space in nature and may vacillate between old and
emergent thoughts that may be disruptive. However, once in the “liminal” psychological space, the
individual experiences a sense of calm and mastery. The immersion into nature may lead to a
transformative way of knowing and understanding the self. These noteworthy concepts may serve
as foundations for future research studies.
3.9. Limitations
Limitations of this review include the biases among the authors of the studies and articles culled,
as well as the conceivable restrictions of SY as an evidence based practice within the traditional
principles of Western medicine. While search criteria for the articles remained consistent across all
database searches, publication bias must be acknowledged as most of the studies reviewed
demonstrate a positive correlation among SY practice and NT with favorable physiological and
psychological outcomes. In addition, original study sample sizes were often limited to less than
20 participants, with the inclusion criteria of primarily of healthy, young, male university students,
making results difficult to generalize across entire populations. Other limitations within the studies
include their inability to distinguish physical and psychological effects purely based on the
participants’ surroundings versus the participants’ level of activity while present in either an urban
or nature setting. Most studies offer little distinction among senses used, and which, if any, have a
greater influence on positive or negative outcomes. While the current research has continued to trend
toward the benefits of SY and NT on specific disease states and diagnoses, it has primarily focused
on the short-term effects of the practice of SY and NT with little research to indicate the longevity of
its benefits. This concept of permanence relates not only to the amount of time spent in a nature
setting for short-term optimal results within a study timeframe, but the participants’ previous
relationship with nature throughout their lifetime, and how a priming bias may influence the
amplitude and frequency of corporeal effects. SY as a therapeutic practice to be exemplified by
healthcare providers and recommended to their patients includes the limitations of theoretically
defining SY for clinical use, the social and economic determinants of health which limit access to
natural environments, and the correlation between the ever changing diversity of nature itself and
the unpredictable physiological and psychological responses it may induce within the human body
as noted by the Biophilia Hypothesis [8].
4. Discussion
4.1. Overview of Health Benefits of SY and NT
In general, from a physiological perspective, significant empirical research findings point to a
reduction in human heart rate and blood pressure and an increase in relaxation for participants
exposed to natural GS [13,40]. Even research involving the use of nature videos of the forest or the
ocean have the same physiological effects [60]. From a qualitative and psychological perspective,
Danish participants reported a sense of safety, calm and overall general wellbeing following exposure
or engagement with nature [63]. South Korean participants with a known alcohol addiction and high
pre-test scores of depression benefited more from the Forest Therapy Camp than participants with
lower pre-test scores of depression and alcohol abuse [35]. Differences in culture, gender, education,
marital or economic status were not associated confounding factors in many of the empirical studies.
Overall, our review of the literature, as illustrated in Table 1, points to positive health benefits
associated with SY and NT while confounding factors were clearly identified by the researchers.
4.2. Implications for Future Research
The aims of this state-of-the-art review are to showcase and elucidate the existing research on
the effects of the practice of SY and NT on human physiological and psychological systems, existing
frameworks and sense metrics in order to assist researchers in conducting future empirical research
to substantiate, gain a better insight and enrich the scholarly literature. Longitudinal research is
Int. J. Environ. Res. Public Health 2017, 14, 851 31 of 37
recommended to investigate the powers of nature as a healer and preventative element in today’s
modern/technological driven world over a long period of time. Proposed thoughtful and well-
designed research would include both quantitative and qualitative approaches to identify specific SY
and NT factors that influence disease and health promotion in Western Cultures. Furthermore, a
systematic review of the current literature would honor the scholarly work completed to date and
provide a higher level of evidence for the practitioner considering SY and NT as EBP interventions.
4.3. Implications for Future Healthcare Practice
This in-depth review illustrates, honors and supports the increased awareness of the positive
health-related effects (e.g., stress reduction and increased holistic well-being) associated with humans
spending time in nature, viewing nature scenes via video, being exposed to foliage and flowers
indoors and the development of urban green spaces in large metropolitan areas worldwide. Not only
valid and reliable psychometrics have been implemented, but valid and reliable physiological
measurements have been used to show significant and potentially healing and health promoting
effects. Furthermore, physiological and psychological research, based on sound NT frameworks and
hypotheses is needed in the areas of healthcare professional/student stress-reduction and life balance
[64,65].
Healthcare professionals and educators may turn to the SY and NT literature for simple,
affordable and enjoyable complementary interventions to reduce stress, anxiety, and depression
symptoms and enhance joy, relaxation, overall sense of well-being and balance in life. The founder
and faculty member of the Association of Nature and Forest Therapy Guides and Programs, Amos
Clifford, states the organization’s mission is to integrate FT into healthcare systems [62]. Moreover,
the profession of nursing and medicine has moved toward an integrative approach to healthcare. The
third integrative nursing principle: “Nature has healing and restorative properties that contribute to
health and well-being” supports the health benefits associated with the practice of SY and NT and
serves as a part of the integrated healthcare model [66]. Furthermore, SY as a healing and restorative
modality may support the clinician’s and patient’s whole-being while promoting a sense of peace,
dignity and comfort. These ideas are supported by Watson’s Carative Processes [67], specifically
Process Eight: Creating healing environment at all levels, whereby wholeness, beauty, comfort, dignity, and
peace are potentiated.
5. Conclusions
Advancements in complementary and alternative medicine (CAM) are indicative of a time in
history when researchers and practitioners are willing to look at how humans evolved over the past
6- to 7-million years. When one ponders humans existing less than 0.01% of the species’ history in
modern surroundings and the other 99.99% of the time living in nature, it is no wonder some humans
yearn and are drawn back to where human physiological/psychological functions began and were
naturally supported. The Biophilia Hypothesis [8] supports SY and NT because it is steeped in the
idea humans have an inner biological attraction to nature and its importance in our human
development. Moreover, psychologically and spiritually speaking, humans intuitively know the
relaxing, soothing and “awe” effects of being in or viewing forests, plants, flowers, urban green
spaces, parks and natural wooden materials [68,69]. The mind-body-spirit experience associated with
SY is for all humans and may be accomplished in various documented ways as illustrated in the novel
review. These methods are supported by current scientific data, history and personal experiences
reported over time. The practice of SY and NT are ontological realism and offer humans an authentic
way of healing and health prevention for the mind, body and spirit [70–72]. How might we continue
to encourage this health-promotion method and demonstrate scientifically and intuitively in order to
add to EBP and global healthcare systems?
Acknowledgments: In great appreciation for the USF School of Nursing and Health Professions’ Faculty
Development Fund Committee for granting funds to publish in an Open Access journal. Claire Sharifi, Associate
Int. J. Environ. Res. Public Health 2017, 14, 851 32 of 37
Librarian: Liaison to the USF School of Nursing and Health Professions for her tireless support. CiCi Lee,
Independent Artist, thank you for contributing the nature photograph (Figure 3).
Author Contributions: Margaret M. Hansen led the research as Primary Investigator and contributed to the
writing/editing of the review. Reo Jones culled the research papers, organized and prepared the tables, literature
search figure, contributed to the writing/editing of the review and supervised Kirsten Tocchini. Kirsten Tocchini
organized the research papers and contributed to the writing/editing of the review.
Conflicts of Interest: The authors declare no conflict of interest.
References
1. Bowler, D.E.; Buyung-Ali, L.M.; Knight, T.M.; Pullin, A.S. A systematic review of evidence for the added
benefits to health of exposure to natural environments. BMC Public Health 2010, 10, 456, doi:10.1186/1471-
2458-10-456.
2. Chun, M.H.; Chang, M.C.; Lee, S. The effects of forest therapy on depression and anxiety in patients with
chronic stroke. Int. J. Neurosc. 2017, 127, 199–203, doi:10.3109/00207454.2016.1170015.
3. Han, J.; Choi, H.; Jeon, Y.; Yoon, C.; Woo, J.; Kim, W. The Effects of Forest Therapy on Coping with Chronic
Widespread Pain: Physiological and Psychological Differences between Participants in a Forest Therapy
Program and a Control Group. Int. J. Environ. Res. Public Health 2016, 13, 255, doi:10.3390/ijerph13030255.
4. Anonymous. Shinrin Yoku. Available online: http://www.shinrin-yoku.org/shinrin-yoku.html (accessed
on 21 July 2017).
5. Williams, F. This Is Your Brain on Nature. Natl. Geogr. 2016, 229.
6. Kaplan, R.; Kaplan, S. The Experience of Nature: A Psychological Perspective; Cambridge University Press:
Cambridge, UK, 1989.
7. Ulrich, R.S.; Simons, R.F.; Losito, B.D.; Fiorito, E.; Miles, M.A.; Zelson, M. Stress recovery during exposure
to natural and urban environments. J. Environ. Psychol. 1991, 11, 201–230.
8. Kellert, S.R.; Wilson, E.O. The Biophilia Hypothesis; Island Press: Washington, DC, USA, 1993.
9. Song, C.; Ikei, H.; Miyazaki, Y. Physiological Effects of Nature Therapy: A Review of the Research in Japan.
Int. J. Environ. Res. Public Health 2016, 13, 781, doi:10.3390/ijerph13080781.
10. Sifferlin, A. The healing power of nature. Time Mag. 2016, 188, 24–26.
11. Igarashi, M.; Song, C.; Ikei, H.; Miyazaki, Y. Effect of Stimulation by Foliage Plant Display Images on
Prefrontal Cortex Activity: A Comparison with Stimulation using Actual Foliage Plants. J. Neuroimaging
2015, 25, 127–130, doi:10.1111/jon.12078.
12. Livni, E. Trees Please: The Japanese Practice of ‘Forest Bathing’ Is Scientifically Proven to Improve Your
Health. 2016. Available online: https://qz.com/804022/health-benefits-japanese-forest-bathing/ (accessed on
26 April 2017).
13. Tsunetsugu, Y.; Park, B.; Miyazaki, Y. Trends in research related to “Shinrin-yoku” (taking in the forest
atmosphere or forest bathing) in Japan. Environ. Health Prev. Med. 2010, 15, 27–37.
14. Jo, H.; Rodiek, S.; Fujii, E.; Miyazaki, Y.; Park, B.-J.; Ann, S.-W. Physiological and Psychological Response
to Floral Scent. HortScience 2013, 48, 82–88.
15. Igarashi, M.; Miwa, M.; Ikei, H.; Song, C.; Takagaki, M.; Miyazaki, Y. Physiological and Psychological
Effects of Viewing a Kiwifruit (Actinidia deliciosa ‘Hayward’) Orchard Landscape in Summer in Japan. Int.
J. Environ. Res. Public Health 2015, 12, 6657–6668.
16. Ikei, H.; Song, C.; Miyazaki, Y. Effects of olfactory stimulation by α-pinene on autonomic nervous activity.
J. Wood Sci. 2016, 62, 568–572.
17. Kobayashi, H.; Park, B.; Miyazaki, Y. Normative references of heart rate variability and salivary alpha-
amylase in a healthy young male population. J. Physiol. Anthropol. 2012, 31, 9, doi:10.1186/1880-6805-31-9.
18. Kobayashi, H.; Song, C.; Ikei, H.; Kagawa, T.; Miyazaki, Y. Analysis of Individual Variations in Autonomic
Responses to Urban and Forest Environments. Evid. Based Complement. Altern. Med. 2015, 2015, 671094.
19. Koga, K.; Iwasaki, Y. Psychological and physiological effect in humans of touching plant foliage—Using
the semantic differential method and cerebral activity as indicators. J. Physiol. Anthropol. 2013, 32, 7,
doi:10.1186/1880-6805-32-7.
Int. J. Environ. Res. Public Health 2017, 14, 851 33 of 37
20. Lee, M.; Lee, J.; Park, B.; Miyazaki, Y. Interaction with indoor plants may reduce psychological and
physiological stress by suppressing autonomic nervous system activity in young adults: A randomized
crossover study. J. Physiol. Anthropol. 2015, 34, 21, doi:10.1186/s40101-015-0060-8.
21. Lee, J.; Park, B.J.; Tsunetsugu, Y.; Ohira, T.; Kagawa, T.; Miyazaki, Y. Effect of forest bathing on
physiological and psychological responses in young Japanese male subjects. Public Health 2011, 125, 93–100,
doi:10.1016/j.puhe.2010.09.005.
22. Lee, J.; Tsunetsugu, Y.; Takayama, N.; Park, B.; Li, Q.; Song, C.; Komatsu, M.; Ikei, H.; Tyrväinen, L.;
Kagawa, T.; et al. Influence of Forest Therapy on Cardiovascular Relaxation in Young Adults. Evid. Based
Complement. Altern. Med. 2014, 2014, doi:10.1155/2014/834360.
23. Li, Q.; Morimoto, K.; Kobayashi, M.; Inagaki, H.; Katsumata, M.; Hirata, Y.; Hirata, K.; Suzuki, H.; Li, Y.J.;
Wakayama, Y.; et al. Visiting a forest, but not a city, increases human natural killer activity and expression
of anti-cancer proteins. Int. J. Immunopathol. Pharmacol. 2008, 21, 117–127.
24. Mao, G.X.; Lan, X.G.; Cao, Y.B.; Chen, Z.M.; He, Z.H.; Lv, Y.D.; Wang, Y.Z.; Hu, X.L.; Wang, G.F.; Yan, J.
Effects of short-term forest bathing on human health in a broad-leaved evergreen forest in Zhejiang
Province, China. Biomed. Environ. Sci. 2012, 25, 317–324.
25. Ochiai, H.; Ikei, H.; Song, C.; Kobayashi, M.; Miura, T.; Kagawa, T.; Li, Q.; Kumeda, S.; Imai, M.; Miyazaki,
Y. Physiological and Psychological Effects of a Forest Therapy Program on Middle-Aged Females. Int. J.
Environ. Res. Public Health 2015, 12, 15222–15232.
26. Park, B.; Furuya, K.; Kasetani, T.; Takayama, N.; Kagawa, T.; Miyazaki, Y. Relationship between
psychological responses and physical environments in forest settings. Landsc. Urban Plan. 2011, 102, 24–32.
27. Park, B.-J.; Tsunetsugu, Y.; Kasetani, T.; Hirano, H.; Kagawa, T.; Sato, M.; Miyazaki, Y. Physiological effects
of Shinrin-yoku (taking in the atmosphere of the forest)—Using salivary cortisol and cerebral activity as
indicators. J. Physiol. Anthropol. 2007, 26, 123–128.
28. Joung, D.; Kim, G.; Choi, Y.; Lim, H.; Park, S.; Woo, J.; Park, B. The Prefrontal Cortex Activity and
Psychological Effects of Viewing Forest Landscapes in Autumn Season. Int. J. Environ. Res. Public Health
2015, 12, 7235–7243.
29. Mao, G.; Cao, Y.; Lan, X.; He, Z.; Chen, Z.; Wang, Y.; Hu, X.; Lv, Y.; Wang, G.; Yan, J. Therapeutic effect of
forest bathing on human hypertension in the elderly. J. Cardiol. 2012, 60, 495–502.
30. McCaffrey, R.; Hansen, C.; McCaffrey, W. Garden Walking for Depression: A Research Report. Holist. Nurs.
Pract. 2010, 24, 252–259.
31. Kim, W.; Lim, S.; Chung, E.; Woo, J. The Effect of Cognitive Behavior Therapy-Based Psychotherapy
Applied in a Forest Environment on Physiological Changes and Remission of Major Depressive Disorder.
Psychiatry Investig. 2009, 6, 245–254.
32. Morita, E.; Imai, M.; Okawa, M.; Miyaura, T.; Miyazaki, S. A before and after comparison of the effects of
forest walking on the sleep of a community-based sample of people with sleep complaints. Biopsychosoc.
Med. 2011, 5, 13, doi:10.1186/1751-0759-5-13.
33. Nakau, M.; Imanishi, J.; Imanishi, J.; Watanabe, S.; Imanishi, A.; Baba, T.; Hirai, K.; Ito, T.; Chiba, W.;
Morimoto, Y. Spiritual care of cancer patients by integrated medicine in urban green space: A pilot study.
Explore 2013, 9, 87–90, doi:10.1016/j.explore.2012.12.002.
34. Ohtsuka, Y. Effect of the Forest Environment on Blood Glucose; Li, Q., Ed.; Forest Medicine; Nova: Hauppauge,
NY, USA, 2012; pp. 109–114.
35. Shin, W.S.; Shin, C.S.; Yeoun, P.S. The influence of forest therapy camp on depression in alcoholics. Environ.
Health Prev. Med. 2012, 17, 73–76.
36. Stigsdotter, U.K.; Ekholm, O.; Schipperijn, J.; Toftager, M.; Kamper-Jørgensen, F.; Randrup, T.B. Health
promoting outdoor environments—Associations between green space, and health, health-related quality
of life and stress based on a Danish national representative survey. Scand. J. Public Health 2010, 38, 411–417.
37. Park, B.-J.; Tsunetsugu, Y.; Kasetani, T.; Morikawa, T.; Kagawa, T.; Miyazaki, Y. Physiological effects of
forest recreation in a young conifer forest in Hinokage Town, Japan. Silva Fenn. 2009, 43, 291–301.
38. Park, B.-J.; Tsunetsugu, Y.; Ishii, H.; Furuhashi, S.; Hirano, H.; Kagawa, T.; Miyazaki, Y. Physiological
effects of Shinrin-yoku (taking in the atmosphere of the forest) in a mixed forest in Shinano Town, Japan.
Scand. J. For. Res. 2008, 23, 278–283.
39. Song, C.; Ikei, H.; Igarashi, M.; Takagaki, M.; Miyazaki, Y. Physiological and Psychological Effects of a Walk
in Urban Parks in fall. Int. J. Environ. Res. Public Health 2015, 12, 14216–14228.
Int. J. Environ. Res. Public Health 2017, 14, 851 34 of 37
40. Tsunetsugu, Y.; Park, B.; Ishii, H.; Hirano, H.; Kagawa, T.; Miyazaki, Y. Physiological effects of Shinrin-
yoku (taking in the atmosphere of the forest) in an old-growth broadleaf forest in Yamagata Prefecture,
Japan. J. Physiol. Anthropol. 2007, 26, 135–142.
41. Song, C.; Ikei, H.; Kobayashi, M.; Miura, T.; Taue, M.; Kagawa, T.; Li, Q.; Kumeda, S.; Imai, M.; Miyazaki, Y.
Effect of Forest Walking on Autonomic Nervous System Activity in Middle-Aged Hypertensive Individuals:
A Pilot Study. Int. J. Environ. Res. Public Health 2015, 12, 2687–2699.
42. Kardan, O.; Gozdyra, P.; Misic, B.; Moola, F.; Palmer, L.J.; Paus, T.; Berman, M.G. Neighborhood greenspace
and health in a large urban center. Sci. Rep. 2015, 5, 1–14.
43. Grazuleviciene, R.; Vencloviene, J.; Kubilius, R.; Grizas, V.; Dedele, A.; Grazulevicius, T.; Ceponiene, I.;
Tamuleviciute-Prasciene, E.; Nieuwenhuijsen, M.J.; Jones, M.; et al. The Effect of Park and Urban
Environments on Coronary Artery Disease Patients: A Randomized Trial. BioMed Res. Int. 2015, 2015,
403012.
44. Jia, B.B.; Yang, Z.X.; Mao, G.X.; Lyu, Y.D.; Wen, X.L.; Xu, W.H.; Lyu, X.L.; Cao, Y.B.; Wang, G.F. Health
Effect of Forest Bathing Trip on Elderly Patients with Chronic Obstructive Pulmonary Disease. Biomed.
Environ. Sci. 2016, 29, 212–218, doi:10.3967/bes2016.026.
45. Ohtsuka, Y. Walking in a Forest Is Beneficial for Type 2 Diabetic Patients; Li, Q., Ed.; Forest Medicine; Nova:
Hauppauge, NY, USA, 2012; pp. 109–114.
46. Morita, E.; Fukuda, S.; Nagano, J.; Hamajima, N.; Yamamoto, H.; Iwai, Y.; Nakashima, T.; Ohira, H.;
Shirakawa, T. Psychological effects of forest environments on healthy adults: Shinrin-yoku (forest-air
bathing, walking) as a possible method of stress reduction. Public Health 2007, 121, 54–63,
doi:10.1016/j.puhe.2006.05.024.
47. Sung, J.; Woo, J.; Kim, W.; Lim, S.; Chung, E. The effect of cognitive behavior therapy-based “forest
therapy” program on blood pressure, salivary cortisol level, and quality of life in elderly hypertensive
patients. Clin. Exp. Hypertens. 2012, 34, 1–7, doi:10.3109/10641963.2011.618195.
48. Largo-Wight, E.; Chen, W.W.; Dodd, V.; Weiler, R. Healthy Workplaces: The Effects of Nature Contact at
Work on Employee Stress and Health. Public Health Rep. 2011, 126, 124–130.
49. Takayama, N.; Korpela, K.; Lee, J.; Morikawa, T.; Tsunetsugu, Y.; Park, B.; Li, Q.; Tyrväinen, L.; Miyazaki, Y.;
Kagawa, T. Emotional, Restorative and Vitalizing Effects of Forest and Urban Environments at Four Sites
in Japan. Int. J. Environ. Res. Public Health 2014, 11, 7207–7230, doi:10.3390/ijerph110707207.
50. Kang, B.; Kim, T.; Kim, M.J.; Lee, K.H.; Choi, S.; Lee, D.H.; Kim, H.R.; Jun, B.; Park, S.Y.; Lee, S.J.; et al. Relief
of Chronic Posterior Neck Pain Depending on the Type of Forest Therapy: Comparison of the Therapeutic
Effect of Forest Bathing Alone Versus Forest Bathing with Exercise. Ann. Rehabil. Med. 2015, 39, 957–963,
doi:10.5535/arm.2015.39.6.957.
51. Hawker, G.A.; Mian, S.; Kendzerska, T.; French, M. Measures of adult pain: Visual Analog Scale for Pain
(VAS Pain), Numeric Rating Scale for Pain (NRS Pain), McGill Pain Questionnaire (MPQ), Short-Form
McGill Pain Questionnaire (SF-MPQ), Chronic Pain Grade Scale (CPGS), Short Form-36 Bodily Pain Scale
(SF-36 BPS), and Measure of Intermittent and Constant Osteoarthritis Pain (ICOAP). Arthritis Care Res. 2011,
63, S240–S252, doi:10.1002/acr.20543.
52. Beil, K.; Hanes, D. The Influence of Urban Natural and Built Environments on Physiological and
Psychological Measures of Stress—A Pilot Study Int. J. Environ. Res. Public Health 2013, 10, 1250–1267,
doi:10.3390/ijerph10041250.
53. Kobayashi, H.; Miyazaki, Y. Distribution characteristics of salivary cortisol measurements in a healthy
young male population. J. Physiol. Anthropol. 2015, 34, 30, doi:10.1186/s40101-015-0068-0.
54. Engert, V.; Vogel, S.; Efanov, S.I.; Duchesne, A.; Corbo, V.; Ali, N.; Pruessner, J.C. Investigation into the
cross-correlation of salivary cortisol and alpha-amylase responses to psychological stress.
Psychoneuroendocrinology 2011, 36, 1294–1302, doi:10.1016/j.psyneuen.2011.02.018.
55. Fisher, D.; Ramachandran, G. The Man Who Planted Trees: A Conversation with David Milarch, by
Awakin Call Editors. 2017. Available online:http://www.dailygood.org/story/1549/the-man-who-planted-
trees-a-conversation-with-david-milarch-awakin-call-editors/ (accessed on 21 July 2017).
56. Igarashi, M.; Aga, M.; Ikei, H.; Namekawa, T.; Miyazaki, Y. Physiological and Psychological Effects on High
School Students of Viewing Real and Artificial Pansies. Int. J. Environ. Res. Public Health 2015, 12, 2521–2531,
doi:10.3390/ijerph120302521.
Int. J. Environ. Res. Public Health 2017, 14, 851 35 of 37
57. Tsutsumi, M.; Nogaki, H.; Shimizu, Y.; Stone, T.E.; Kobayashi, T. Individual reactions to viewing preferred
video representations of the natural environment: A comparison of mental and physical reactions. Jpn. J.
Nurs. Sci. 2017, 14, 3–12, doi:10.1111/jjns.12131.
58. Park, B.J.; Tsunetsugu, Y.; Kasetani, T.; Kagawa, T.; Miyazaki, Y. The physiological effects of Shinrin-yoku
(taking in the forest atmosphere or forest bathing): Evidence from field experiments in 24 forests across
Japan. Environ. Health Prev. Med. 2010, 15, 18–26, doi:10.1007/s12199-009-0086-9.
59. Logan, A.C.; Selhub, E.M. Vis Medicatrix naturae: Does nature “minister to the mind”? BioPsychoSoc. Med.
2012, 6, 11, doi:10.1186/1751-0759-6-11.
60. Selhub, E.M.; Logan, A.C. Your Brain on Nature: The Science of Nature’s Influence on Your Health, Happiness
and Vitality; Wiley: Somerset, NJ, USA, 2012.
61. Berger, R. Building a home in nature: An innovative framework for practice. J. Hum. Psychol. 2008, 48,
264–279, doi:10.1177/0022167807306990.
62. Zdravkovic, S.; Clifford, A.M. Workshops and Retreats. Available online: http://www.
natureandforesttherapy.org/workshops-and-retreats.html (accessed on 28 April 2017).
63. Poulsen, D.V.; Stigsdotter, U.K.; Djernis, D.; Sidenius, U. ‘Everything just seems much more right in nature’:
How veterans with post-traumatic stress disorder experience nature-based activities in a forest therapy
garden. Health Psychol. Open 2016, 3, doi:10.1177/2055102916637090.
64. Beck, D.L.; Srivastava, R. Perceived level and sources of stress in baccalaureate nursing students. J. Nurs.
Educ. 1991, 30, 127–133.
65. Reeve, K.L.; Shumaker, C.J.; Yearwood, E.L.; Crowell, N.A.; Riley, J.B. Perceived stress and social support
in undergraduate nursing students’ educational experiences. Nurse Educ. Today 2013, 33, 419–424,
doi:10.1016/j.nedt.2012.11.009.
66. Kreitzer, M.J. Integrative nursing: Application of principles across clinical settings. Rambam Maimonides
Med. J. 2015, 6, e0016, doi:10.5041/RMMJ.10200.
67. Watson, J. Core Concepts of Jean Watson’s Theory of Human Caring/Caring Science. 2010. Available online:
https://www.watsoncaringscience.org/files/Cohort%206/watsons-theory-of-human-caring-core-concepts-
and-evolution-to-caritas-processes-handout.pdf (accessed on 21 July 2017).
68. Olsson, A.; Lampic, C.; Skovdahl, K.; Engström, M. Persons with early-stage dementia reflect on being outdoors:
A repeated interview study. Aging Ment. Health 2013, 17, 793–800, doi:10.1080/13607863.2013.801065.
69. Song, C.; Ikei, H.; Kobayashi, M.; Miura, T.; Li, Q.; Kagawa, T.; Kumeda, S.; Imai, M.; Miyazaki, Y. Effects
of viewing forest landscape on middle-aged hypertensive men. Urban For. Urban Green. 2017, 21, 247–252,
doi:10.1016/j.ufug.2016.12.010.
70. Berger, R.; Tiry, M. The enchanting forest and the healing sand—Nature therapy with people coping with
psychiatric difficulties. Arts Psychother. 2012, 39, 412–416, doi:10.1016/j.aip.2012.03.009.
71. Berger, R. Going on a journey: A case study of nature therapy with children with a learning difficulty. Emot.
Behav. Diffic. 2008, 13, 315–326, doi:10.1080/13632750802440361.
72. Berger, R. Nature Therapy: A Framework That Incorporates Nature, the Arts and Ritual in Therapy; Kopytin, A.,
Rugh, M., Kopytin, A., Rugh, M., Eds.; Nova Science Publishers: Hauppauge, NY, USA, 2016; pp. 27–45.
© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).
... In addition another category of programme activities was added based on the recommendations in this scoping review [24], that was explicitly directed towards reflective practices in the natural environment [29]. This category included the following formal (guided) and informal exercises: daily check-in and check-outs for (group) reflection, forest bathing [34], journaling, mindfulness, meditation (walking meditation, silent kayaking, 5-senses meditation, loving-kindness meditation [35]). The content of the WAYA programme was further developed through patient and public involvement by way of input and feedback on programme activities from representatives/members from the national cancer associations (Ung Cancer (n = 3) and The Swedish Childhood Cancer Fund (n = 2)), as well as from wilderness/outdoor instructors (n = 2) from the Swedish Survival Guild. ...
... Aspects of the wilderness setting were also used to support the mindfulness exercises, in line with programme aim numbers 3-5. These included forest bathing [34] along a valley of an old-growth forest, silent walks, attentive listening, and silent kayaking along a coastal forest, all of which were intended to encourage awareness practice, support an experience of balance and harmony within the natural surroundings, and allow an opportunity to share these experiences and their thoughts about them with other members of the group during daily check-in and check-outs. Programme aim number 6 was primarily addressed by way of teaching bushcraft skills. ...
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Detailed descriptions of theory, structure, and activities with causal links to specified outcomes of wilderness programs are lacking. Addressing this gap, the present qualitative study gives a thorough description of the development of the Wilderness programme for Adolescent and Young Adult (AYA) cancer survivors (WAYA). WAYA is adapted to the individual needs of AYA cancer survivors. It was conceived around Næss’s ecosophy and the Positive Health Model, and refined based on findings from a scoping review and patient/public involvement. Programme aims were to increase physical activity, self-confidence, personal growth, joy, safety within nature, meaningful relationships, and self-efficacy. The programme was an eight-day expedition followed three months later by a four-day base-camp. Activities included hiking, backpacking, kayaking, rock climbing, mindfulness and bushcrafting. Evaluation of the programme through focus group and individual interviews with 15 facilitators and 17 participants demonstrated that a diverse group of participants, challenging activities, and mindfulness-based practices were found to positively influence group bonding and the learning process. Furthermore, including an expedition and base-camp component was found to be beneficial in supporting the development of participants’ own personal outdoor practices. In conclusion, this study demonstrated that the WAYA programme is safe and well accepted by AYA cancer survivors.
... Die positiven gesundheitlichen Effekte gehen daher über das kurzfristige Wohlbefinden hinaus, weil durch die Blutdruckreduktion das Risiko für Herz-und Gefäßerkrankungen insgesamt gemindert werden kann. Shirin-Yoku ist in der japanischen und südkoreanischen Tradition als ein multisensorisches Walderleben angelegt (Hansen et al., 2017). In langsamen Spaziergängen, unterbrochen von Pausen, werden unterschiedliche Sinne angesprochen (vgl. ...
... Mit dem Cortisolspiegel lässt sich das Stressniveau von Personen einschätzen. Waldaufenthalte führen zu einer Absenkung des Cortisolspiegels, daran gekoppelt sind dann weitere Effekte wie eine verminderte Anspannung und weniger negative Emotionen (Hansen et al., 2017;Kobayashi et al., 2017). Bereits ein kurzer Waldspaziergang von 20 min kann die Stresshormone signifikant absinken lassen und damit zu einer Entspannung, Regeneration und Erholung beitragen (Hunter et al., 2019). ...
... The interior health design offers lighting mimicking natural daylight that supports the biorhythms and indoor plants and green walls. The green interior and exterior design is aesthetic, but is also an opportunity for restoration and stress relief in an urban working life e.g., [61][62][63]. The building´s health design incorporates facilities to promote a healthy lifestyle, e.g., multi-purpose sports courts, an edible garden, and a demonstration kitchen for healthy cooking. ...
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This explorative case study investigates health-promoting office design from an experience and meaning-making perspective in an activity-based flex-office (A-FO) in a headquarter building. This small case study (n = 11) builds using qualitative data (walk-through and focus group interviews). A reflexive thematic analysis (RTA) of the experience of design approach was performed on this from a health and sustainability perspective, including the physical, mental, and social dimensions of health defined by WHO. Results show a wide range in participants' experiences and meaning-making of the health-promoting office design of their office building. The control aspect plays a central role in participants' experiences, including factors such as surveillance and obeyance, related to status and power, in turn associated with experiences of pleasantness, symbolism , and inclusiveness. Three main themes are identified in participants´ experiences: (1) comfort -non-comfort, (2) outsider-insider, and (3) symbolism. The major finding of the study is the ambiguity among participants about the health-supportive office design of the office building per se and its various environments. There is a sense that it is chafing, due to dissonance between the intention of the office and the applied design.
... "Shinrin-yoku" (SY) or "forest bathing" is a traditional Japanese practice of immersing oneself in nature while mindfully using all five senses; it appears to be associated with beneficial effects on the immune system function (increase in natural killer cells/cancer prevention); the cardiovascular system (hypertension/coronary artery disease); the respiratory system (allergies and respiratory disease); depression and anxiety (mood disorders and stress); mental relaxation (attention-deficit/hyperactivity disorder) and human feelings of "awe" (increase in gratitude and selflessness) [63]. After the practice, patients reported lower concentrations of cortisol, lower pulse rate, lower blood pressure as well as greater parasympathetic nerve activity, and lower sympathetic nerve activity than in city environments [64]. ...
... Des travaux, notamment menés au Japon, se sont intéressés aux effets liés au contact avec les milieux forestiers sur la santé humaine, et plus particulièrement à travers le concept de "shinrin-yoku" (bains de forêt)(Hansen, Jones, et Tocchini 2017). Il s'agit de processus d'immersion et de recherche de contact avec la forêt dans un objectif de détente, les bienfaits de ce milieu sont notamment induits par les substances volatiles organiques qu'il dégage (phytoncides). ...
Thesis
This PhD. focuses on the conditions of protection of the wilderness in Europe, which has become a central concept in the field of environmental conservation. Such areas are considered by their promoters as a means to respond to the contemporary major ecological challenges (e.g. battle against climate change, global biodiversity loss). In 2009, the European Parliament adopted a resolution encouraging State Members to designate large areas in a natural state in which all major human interference must be avoided. Since the end of the 2000s, many wilderness initiatives have emerged at various scales (i.e. local, national, international) across Europe. The aim of this research is to study the requirements for implementing wilderness protection strategies across Europe in di erent cultural and socio-ecological contexts and the limitations that emerge from these territories. Using a qualitative methodology, semi-structured interviews were conducted in the UK, the Netherlands and France, as well as with actors with European influence. This thesis shows that many stakeholders, mainly from NGOs, are utilizing this concept throughout Europe and are trying to implement its applications in different areas. These attempts could provide feedback on the issues that must be addressed and on the technical requirements necessary when carrying out wilderness projects. However, because the concept of wilderness is a cultural construct, it is difficult to grasp and to transpose. The difficulty to obtain a universal definition of the notion has led to the development of substitute concepts closer to the realities on the field (e.g. wild land, rewilding, free evolution), which result in the implementation of various strategies whose common goal is to promote the recovery of natural processes. Wilderness, shaped by local socio-ecological conditions, thus appears to be a means of rethinking nature protection policies at national and European levels, but also of reinventing the relationship between humans and non-humans.
... Así, la primera forma se condensó como una nueva línea de la Psicología Arquitectónica, que ya tenía sus orígenes en los intentos de Proshansky, Ittelson y Rivlin (1976) por medir aquellas condiciones ambientales que permitían que los manicomios fueran un espacio propicio para la salud mental, o no. El segundo caso fue el predilecto de los Kaplan, y tiene su versión más moderna en los "shinrin-yoku" (en japonés) o baños forestales: recorridos guiados por la naturaleza, con el fin de restaurar y propiciar una mejor salud (Hansen et al., 2017). ...
... As mentioned above, forest therapy offers solutions to a number of public health problems, such as lifestyle disorders, stress, mental health problems, cardiovascular problems, etc., due to its documented health benefits [18]. The benefits and efficacy of forest therapy have been recognized by the public as a "bridge" between people and nature, facilitating people to enter the forest and return to nature, thereby improving health and well-being [21,58]. However, in different countries, due to the influence of development time, culture, and other factors, there are differences in the way and content of forest therapy services. ...
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Forests have provided support for human health and survival since ancient times. With improved public awareness of health issues and the importance of forest ecological functions, forest therapy has gradually gained momentum. Forest therapies have been applied around the world as preventive and alternative therapies to promote human health. As a safe, side-effect-free, low-cost, preventive, and alternative therapy, forest therapy has been scientifically proven to promote physical and mental health in humans. However, the forest therapy service system is still underdeveloped, and forest therapy has not become a mainstream part of clinical medical treatment methods in most countries worldwide. Therefore, in order to better present the development path and current situation of forest therapy in different countries and provide guidance for how other countries can develop similar interventions and clinical sites to base these activities, this study uses Germany, Japan, and China as examples to systematically tease out how forest therapy has developed and the status of forest therapy services in different countries, as well as the health benefits of forest therapy. Furthermore, the key components and traditional cultural and socioeconomic backgrounds related to forest therapy are discussed. Finally, based on published empirical research, we believe that forest therapy can be a solution to public health problems thanks to its multiple, medically proven health benefits. Forest therapy facilitates the return of people to the forest and nature to achieve health and well-being effects. However, there is a need for more research on the mechanisms (such as the immune system, endocrine system, nervous system, etc.) underlying forest therapy’s effectiveness, which should include strengthened collaborations between disciplines. In addition, the role of forest therapy services in promoting human health needs to be emphasized.
... The forest environment affects human health mainly with the synergistic effect of a series of environmental factors, such as phytoncide, negative air ions (NAI), oxygen, and forest microclimate (Kuo, 2015;Riad et al., 2018;Wen et al., 2019). Many epidemiological studies have reported that forest environment could improve cardiopulmonary function, psychological emotion, immunity and stress state (Antonelli et al., 2019;Hansen et al., 2017;Park et al., 2010;Zhang et al., 2020). For example, a randomized controlled study among elderly patients with chronic obstructive pulmonary disease (COPD) indicated that short term forest bathing trip reduced inflammation and stress level (Jia et al., 2016). ...
Article
Forest environment has many health benefits, and negative air ions (NAI) is one of the major forest environmental factors. Many studies have explored the effect of forest environment on cardiac autonomic nervous function, while forest NAI in the among function and the underlying mechanism still remain unclear. To explore the associations and molecular linkages between short-term exposure to forest NAI and heart rate variability (HRV), a repeated-measure panel study was conducted among 31 healthy adults. Participants were randomly selected to stay in a forest park for 3 days and 2 nights. Individual exposures including NAI were monitored simultaneously and HRV indices were measured repeatedly at the follow-up period. Urine samples were collected for non-targeted metabolomics analysis. Mixed-effect models were adopted to evaluate associations among NAI, HRV indices and metabolites. The median of NAI concentration was 68.11 (138.20) cm−3 during the study period. Short-term exposure to forest NAI was associated with the ameliorative HRV indices, especially the excitatory parasympathetic nerve. For instance, per interquartile range increase of 5-min moving average of NAI was associated with 9.99 % (95%CI: 8.95 %, 11.03 %) increase of power in high frequency. Eight metabolites were associated with NAI exposure. The down-regulated tyrosine metabolism was firstly observed, followed by other amino acid metabolic alterations. The NAI-related metabolic changes reflect the reduction of inflammation and oxidative stress. HRV indices were associated with 25 metabolites, mainly including arginine, proline and histidine metabolism. Short-term exposure to forest NAI is beneficial to HRV, especially to the parasympathetic nerve activity, by successively disturbing different metabolic pathways which mainly reflect the increased anti-inflammation and the reduced inflammation. The results will provide epidemiological evidences for developing forest therapy and improving cardiac autonomic nervous function.
... For example, 天人合一 (the harmony between humanity and nature) is a core idea in Chinese culture (Lai et al., 2022). Shinrin-yoku, or forest bathing, is an increasingly popular form of nature therapy used to promote physiological and psychological health in many parts of the world (Hansen et al., 2017). American poet Ralph Waldo Emerson also described "the lover of nature is he whose inward and outward senses are still truly adjusted to each other; who has retained the spirit of infancy even into the era of manhood" (Emerson, Some studies reveal the psychological benefits of landscapes that have few plants or minimal liquid water, such as deserts (Yin et al., 2022). ...
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Numerous studies have highlighted the physical and mental health benefits of contact with nature, typically in landscapes characterized by plants (i.e., “greenspace”) and water (i.e., “bluespace”). However, natural landscapes are not always green or blue, and the effects of other landscapes are worth attention. This narrative review attempts to overcome this limitation in past research by pursuing the following objectives: (1) categorizing these natural landscapes, (2) summarizing the literature on health benefits of exposure to landscapes beyond "greenspace" and "bluespace," and (3) presenting the potential mechanisms underlying any health benefits derived from exposure to these other landscapes. We propose that natural landscapes are composed of at least one of three components: (1) plants (e.g., trees, flowering plants, grasses, sedges mosses, ferns, and algae), (2) water (e.g., rivers, canals, lakes, oceans), and/or (3) rocks and minerals, including soil. Landscapes not dominated by plants or liquid-state water include those with abundant solid-state water (e.g., polar spaces) and rocks or minerals (e.g., deserts, caves). Possible health benefits of solid-state water or rock/mineral dominated landscapes include both shorter-term (i.e., viewing images) and longer-term (i.e., living in these landscapes) exposure durations. Reported benefits span improved emotional and mental states and medical treatment resources for respiratory conditions and allergies.Restorative and instorative mechanisms underlying health benefits consist of commonly discussed theories in the "greenspace" and "bluespace" literature as well as less discussed pathways in that literature. Benefits of shorter-term exposure may be explained by attention restoration theory and stress reduction theory. Benefits of longer-term exposure may result from the cumulative effects of shorter-term exposures as well as psychological benefits explained by post-traumatic growth theory, supportive environment theory, and place attachment. Additional mechanisms may include distinct types of physical activity and immune system benefits, among others.This is the first review to draw attention to the potential salutogenic value of natural landscapes beyond "greenspace" and "bluespace." It is also among the first to highlight the limitations and confusion that result from classifying natural landscapes using colors. Since the extant literature on natural landscapes - beyond those with abundant plants or liquid-state water - is limited in regard to quantity and quality, additional research is needed to understand their restorative potential and therapeutic possibilities.
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Exposure to natural environments has a range of health benefits, including enhancing psychological restoration and cognitive development. While there are various explanations on the causes for the benefits of the natural exposure, such as less air pollution and noise, more physical activity, stronger social interactions, or even more diverse microbial community, etc., this study has zeroed in on the air quality of the natural environment. In addition to low-level pollution, what makes the natural air superior remains unclear. To this end, we conducted a series of psychological evaluation and cognitive tests on a couple of subjects in a national forest park in southwest China. Based on the results, we built an artificial chamber where selected air parameters can be independently manipulated and carried out similar tests in the chamber. We came to the following conclusion. (1) Exposure to real natural environment demonstrated tangible benefits for cognitive performances and mental states and the benefits can be obtained to some extent in the artificial environment by creating air qualities similar to the air in the natural environment. (2) Scents in natural environments may be one of the key beneficial factors. (3) Adopting proper cognitive test is critical for distinguishing the differences made by the natural exposure. Working memory showed marked responses to the natural exposure.
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This chapter presents Nature Therapy, a creative therapeutic discipline, which takes place in nature and relates to it as a partner in the therapeutic process. Relating to concepts from eco-psychology, ritual and drama therapy the chapter presents the fundamental concepts of the framework and demonstrates its possible applications to various populations. It highlights how the integration of nature can broaden, deepen and advance the therapeutic process. The chapter affirms that Nature Therapy is an autonomous and independent framework, as well as serving as a model that can be utilized in arts therapies in general and in drama therapy in particular.
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