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A systematic literature review and meta-analysis of the clinical effects of aroma inhalation therapy on sleep problems

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Background: This systematic review investigated the clinical effects of inhalation aromatherapy for the treatment of sleep problems such as insomnia. Methods: Studies on sleep problems and inhalation aromatherapy, published in Korean and international journals, were included in the meta-analysis. Five domestic and international databases, respectively each, were used for the literature search. Keywords included sleep disorder, sleep problems, insomnia, and aroma inhalation, and the related literature was further searched. After the screening, selected articles were assessed for their quality and conducted the risk of bias using RevMan 5.0, a systematic literature review was then conducted. A meta-analysis comparing the averages was conducted on studies that reported numerical values. Additionally, meta-analysis of variance and meta-regression analyses were performed. Results: Meta-analysis of the 34 studies using the random-effects model revealed that the use of aromatherapy was highly effective in improving sleep problems such as insomnia, including quantitative and qualitative sleep effects (95% confidence interval [CI], effect sizes = 0.6491). Subgroup analysis revealed that the secondary outcomes including stress, depression, anxiety, and fatigue were significantly effective. The single aroma inhalation method was more effective than the mixed aroma inhalation method. Among the single inhalation methods, the lavender inhalation effect was the greatest. Conclusion: Inhalation aromatherapy is effective in improving sleep problems such as insomnia. Therefore, it is essential to develop specific guidelines for the efficient inhalation of aromatherapy. Ethics and dissemination: Ethical approval is not required because individual patient data are not included. The findings of this systematic review were disseminated through peer-reviewed publications or conference presentations. Prospero registration number: CRD42020142120.
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A systematic literature review and meta-analysis
of the clinical effects of aroma inhalation therapy
on sleep problems
Moon Joo Cheong, PhD
a
, Sungchul Kim, KMD, PhD
b
, Jee Su Kim
c
, Hyeryun Lee
c
,
Yeoung-Su Lyu, KMD, PhD
a,c
, Yu Ra Lee
a
, Byeonghyeon Jeon, PhD
a
, Hyung Won Kang, KMD, PhD
c,d,
Abstract
Background: This systematic review investigated the clinical effects of inhalation aromatherapy for the treatment of sleep
problems such as insomnia.
Methods: Studies on sleep problems and inhalation aromatherapy, published in Korean and international journals, were included in
the meta-analysis. Five domestic and international databases, respectively each, were used for the literature search. Keywords
included sleep disorder, sleep problems, insomnia, and aroma inhalation, and the related literature was further searched. After the
screening, selected articles were assessed for their quality and conducted the risk of bias using RevMan 5.0, a systematic literature
review was then conducted. A meta-analysis comparing the averages was conducted on studies that reported numerical values.
Additionally, meta-analysis of variance and meta-regression analyses were performed.
Results: Meta-analysis of the 34 studies using the random-effects model revealed that the use of aromatherapy was highly effective
in improving sleep problems such as insomnia, including quantitative and qualitative sleep effects (95% condence interval [CI], effect
sizes =0.6491). Subgroup analysis revealed that the secondary outcomes including stress, depression, anxiety, and fatigue were
signicantly effective. The single aroma inhalation method was more effective than the mixed aroma inhalation method. Among the
single inhalation methods, the lavender inhalation effect was the greatest.
Conclusion: Inhalation aromatherapy is effective in improving sleep problems such as insomnia. Therefore, it is essential to develop
specic guidelines for the efcient inhalation of aromatherapy.
Ethics and dissemination: Ethical approval is not required because individual patient data are not included. The ndings of this
systematic review were disseminated through peer-reviewed publications or conference presentations.
PROSPERO registration number: CRD42020142120.
Abbreviations: Actigraphy =activity recorder, AMED =Allied and Complementary Medicine Database, BDI =Beck Depression
Inventory, CENTRAL =Cochrane Central Register of Controlled Trials, CINAHL =Cumulative Index to Nursing and Allied Health
Literature, DSM-5 =Diagnostic and Statistical Manual of Mental Disorders-5, ES =effect sizes, FSI =fatigue symptom inventory,
HAMD =Hamilton Depression Scale, ISI =insomnia severity index, KCI =Korea Citation Index, KISS =Korean studies Information
Service System, KMbase =Korean Medical Database, MEDLINE =Medical Literature Analysis and Retrieval System Online, or
MEDLARS Online, meta-ANOVA =meta-analysis of variance, OASIS =Oriental Medicine Advanced Searching Integrated System,
PICOS =Participants, Intervention, Control, Outcomes & Study Design, PRISMA =Preferred Reporting Items for Systematic
Editor: Yoshihiro Shidoji.
Consent for publication: Not applicable.
Availability of data and material: Not applicable.
This research was funded by the Ministry of Health and Welfare and was supported by the Korea Health Industry Promotion Agencys Health and Medical Technology
R&D Project (Grant number: HI20C1951). The funding source will have no input in the interpretation or publication of the study results.
The authors declare that they have no conict of interest.
The datasets generated during and/or analyzed during the current study are not publicly available, but are available from the corresponding author on reasonable
request.
a
Rare Diseases Integrative Treatment Research Institute, Wonkwang University, Jangheung Integrative Medical Hospital, Anyang-myeon, Jangheung-gun, Jeollanam-
do,
b
Center of Amyotrophic Lateral Sclerosis & Motor Neuron Disease, Wonkwang University Gwangju Medical Hospital, Nam-gu, Gwangju,
c
Department of Korean
Neuropsychiatry Medicine, Wonkwang University, Iksan,
d
Department of Korean Neuropsychiatry Medicine & Inam Neuroscience Research Center, Wonkwang
University Sanbon Hospital, Gunpo, Republic of Korea.
Correspondence: Hyung Won Kang, Department of Korean Neuropsychiatry Medicine, Wonkwang University, Iksan, 460, IKsan-daero, Iksan-si Jeollabuk-do, Republic
of Korea/Department of Neuropsychiatry of Korean Medicine & Inam Neuroscience Research Center, Wonkwang University Sanbon Hospital. 321, Sanbon-ro Gunpo
City, Gyeonggi-do 15865, Republic of Korea (e-mail: dskhw@wku.ac.kr).
Copyright ©2021 the Author(s). Published by Wolters Kluwer Health, Inc.
This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to
download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal.
How to cite this article: Cheong MJ, Kim S, Kim JS, Lee H, Lyu YS, Lee YR, Jeon B, Kang HW. A systematic literature review and meta-analysis of the clinical effects
of aroma inhalation therapy on sleep problems. Medicine 2021;100:9(e24652).
Received: 5 June 2020 / Received in nal form: 26 November 2020 / Accepted: 10 January 2021
http://dx.doi.org/10.1097/MD.0000000000024652
Systematic Review and Meta-Analysis Medicine®
OPEN
1
Reviews and Meta-analysis, PSG =polysomnography, PSQI =Pittsburgh Sleep Quality Index, PSS =perceived stress scale, RCT =
randomized controlled trial, RISS =research information service system, SE =sleep efciency, SOL =sleep onset latency, SSQ =
Stanford Sleep Questionnaire, STAI =state-trait anxiety inventory, TST =total sleep time, WASO =wake-up sleep on time, WHIIRS =
Womens Health Initiative Insomnia Rating Scale.
Keywords: aromatherapy, inhalation, insomnia, meta-analysis, sleep problems, systematic literature review
1. Introduction
During sleep, humans undergo physical and mental stress
recovery and rejuvenation.
[13]
Sleep deprivation is common
among the current generation and up to 18% of the worlds
population experiences insomnia.
[4,5]
In Korea, >2 million
people were diagnosed with insomnia over a period of 5 years
(20132017), according to the National Health Insurance
Corporation. A meta-analysis on sleep-related studies assessed
the factors related to sleep disorders and found that stress, a
psychological result, exhibited the highest correlation with sleep
disorders.
[5,6]
However, stress coexists with other diseases in the
current generation, and therefore it is challenging to treat sleep
disorders by only addressing the stress. Additionally, prescrip-
tions for sleep problems include sleep inducers and sleeping pills,
which may lead to other problems in daily life.
[7]
For example, a
sleep disorder patient led to a trafc accident a day after ingesting
sleeping pills, which stay in the body longer than other drugs.
[8]
Recently, interest in programs using psychological interventions
and complementary alternative medicine has increased to reduce
the side effects of prescription drugs and improve the quality of
life of insomnia patients.
[9]
However, there are limitations in
these program applications to those with sleep disorders. Most
programs last 50minutes per session and are performed at least
once a week. As sleep disorder programs are conducted for a
longer period rather than a single session,
[5]
adults that work
during the day or at night
[1012]
have difculties in participating
in such programs. Additionally, those with sleep disorders
experience depression, anxiety, and panic disorder, which also
leads to difculties in program participation.
[1316]
Aroma inhalation therapy for treating sleep disorders has
recently been gaining great interest. Inhalation of aromatic oil
particlesthat stimulate the olfactory sense, directlyaffect the central
nervous system responsible for controlling human emotions and
physiological functions. It regulates the autonomic nervous system,
endocrine system, and immune system, leading to therapeutic
effects on the body.
[17]
Another advantage of aromatherapy is that
individuals can choose their preferred scents, and those that cannot
participate in sleep disorder programs can also undergo aroma-
therapy regardless of thetime and place. In Korea, recent studies on
aroma inhalation therapy have been reported in professional
groups (such as night shift nurses, metropolitan workers)
experiencing sleep disorders.
[11,12]
However, information on
specic methods such as the type of aroma used and the usage
time is unclear.
[14]
Therefore, this study quantitatively analyzed the
effects of aroma inhalation therapy for sleep disorders and assessed
the most effective oil for sleep. This study provides information on
the aroma that can be used by anyone to improve sleep problems in
their daily life and obtain the maximum benecial effects of sleep.
2. Methods
2.1. Study registration
This systematic review was registered in the International
Prospective Register of Systematic Reviews (PROSPERO)
(registration number, CRD42020142120) on March 02, 2020,
and has been reported following the Preferred Reporting Items
for Systematic Reviews and Meta-analysis (PRISMA) guidelines
for systematic reviews.
[18]
2.2. Study design
This systematic literature review and meta-analysis analyzed the
reported effects of the aroma inhalation method on the
improvement of sleep problems.
2.3. Data sources
The literature search was conducted by 3 researchers and 2
methodologists with information collated from domestic and
foreign databases, including 5 Korean-language databases
(Oriental Medicine Advanced Searching Integrated System
[OASIS], Korean Studies Information Service System [KISS],
Research Information Service System [RISS], Korean Medical
Database [KMbase], and Korea Citation Index [KCI]) and 6
English-language databases (MEDLINE via PubMed, EMBASE
via Elsevier, the Allied and Complementary Medicine Database
[AMED] via EBSCO, the Cochrane Central Register of
Controlled Trials [CENTRAL], the Cumulative Index to Nursing
and Allied Health Literature [CINAHL] via EBSCO, and
PsycARTICLES via ProQuest). We also searched the gray
literaturethat including unpublished articles. There were no
language restrictions.
2.4. Search strategies
A presearch was conducted based on the MeSH term for the
treatment of sleep disorders using aromatherapy. Subsequently,
search terms that were included in the search strategy were
implemented following the procedure. The search terms were as
follows: Insomnia,”“Sleep Disorder,”“Sleep Problem,
Aroma Therapy,and Aroma Inhalation therapy.In
addition, for Ovid-MEDLINE, EMBASE, and SIGN, and
PubMed, search lters used in the Shojania et al
[19]
study were
used to increase the specicity of the searches. Furthermore,
existing systematic literature reviews and Cochrane reviews of
relevant topics were considered when constructing the search
strategy.
2.5. Study selection
2.5.1. Types of studies. Studies selected were the randomized
control trials (RCTs). Studies that used inappropriate random
sequence generation methods such as alternate allocation were
excluded. Studies included systematic reviews in experimental
studies where meta-analyzed gures were provided, which
investigated sleep disorders and sleep problems associated with
the inhalation of aroma oil. Specically, the selection of the thesis
was done using the criteria of the core questionnaire PICO
(Patient/Participants/Population/Problem, Intervention, Com-
parison, and Outcome) in this study. Furthermore, to check
Cheong et al. Medicine (2021) 100:9 Medicine
2
the effectiveness of aroma inhalation in improving sleep
problems, the types of aroma, and methods of aroma mixing
were included as adjustment parameters. However, other designs
such as in vivo, in vitro, case reports or studies, retrospective
studies, qualitative studies, uncontrolled trials, and trials, that
failed to provide detailed results, were excluded. Details of the
study design are outlined in Table 1.
2.5.2. Types of participants. We included studies on people
with undiagnosed sleep problems and patients, aged 20 to 60
years, with sleep disorders diagnosed using standardized
diagnostic tools such as the Diagnostic and Statistical Manual
of Mental Disorders-5. There were no restrictions on the sex or
race of the participants.
2.5.3. Types of interventions. The intervention methods were
aroma inhalation methods.
2.6. Types of outcome measures
2.6.1. The primary outcomes. Primary outcomes were sleep
quantitative and qualitative inventories
a. Effect on the quantitative sleep time, which was evaluated
using the following measures:
(1) The activity recorder (actigraphy)
[20]
records the activity
during sleep when worn on the wrist or ankle.
(2) Polysomnography (PSG)
[21]
test measures the physiologi-
cal changes that occur during sleep by measuring the EEG,
EMG, ECG, snoring, respiration, and diagnoses of the
disorder
(3) The sleep diary
[22,23]
used to measure the patients sleep
habits, sleep hygiene, and sleep problems for 2 weeks, and
to evaluate the progress of the treatment.
(4) Total sleep time (TST)
[24]
: insufcient sleep if total sleep
time was lower than.
[25]
(5) Sleep onset latency (SOL)
[26,27]
: insufcient sleep when the
elevation delay time was more than 30 minutes.
(6) Wake-up Sleep On Time (WASO)
[28]
: If the awakening
time was >30 minutes after the elevation, the sleep is
considered insufcient.
(7) Sleep Efciency (SE)
[29]
: Sleep efciency of 85% was
considered insufcient.
b. Effect on quality of sleep
Patient reporting tools used, with proven reliability and
validity, are as follows:
(1) The Pittsburgh Sleep Quality Index (PSQI)
[30]
consists
of 19 self-reporting questions about sleep quality and
discomfort over the past month. The total score ranges from
0 to 21; the lower the total score, the better the quality of
sleep, and the higher the total score, the worse the sleep
quality.
(2) The Insomnia Severity Index (ISI),
[31]
developed to assess
insomnia, is a self-reporting measure that comprises a total of
7 questions. It is a 5-point scale with higher scores indicating
more serious insomnia.
(3) The Medical Outcome Study Sleep Scale,
[32]
consists of 12
questions, measured in the range of 0 to 100; the lower the
score, the better the quality of sleep.
(4) The Stanford Sleep Questionnaire (SSQ)
[33,34]
has 7 classes,
with subjective sleepiness levels of 1 to 7; lower scores
indicate better sleep quality.
(5) The Womens Health Initiative Insomnia Rating Scale
(WHIIRS)
[35]
consists of 5-item scales for sleep initiation
and maintenance and evaluates the subjective sleep quality.
The lower the score, the better the sleep quality.
Table 1
Study type selection according to PICO.
Criteria factor Standard contents
Research method RCTs conducted with the quantitative research method (except for retrospective studies, in vivo, in vitro, case reports or studies,
qualitative studies, and uncontrolled trials)
Research design RCT studies
Purpose Reasonable for the research purposes should be revealed.
Participants/Patients Participants with insomnia and sleep disorders diagnosed using standardized diagnostic tools such as the DSM-5; there was no
restriction on the sex or race of the participants or sleep problems and disorders.
Intervention/Moderate variables Direct/Indirect (such as necklace) inhalation method of aromatherapy
Comparator There was no restriction.
Outcomes -Primary outcomes
Effect on quality of sleep
(1) Pittsburgh Sleep Quality Index (PSQI)
(2) SHV (Synder-Halpern and Verran, 1987)
(3) Insomnia Severity Index
(4) Korean Sleep Scale A
(5) Q.O.S (Quality of Sleep)
(6) VAS
(7) Stanford Sleepiness Scale
(8) NRS (Numeric Rating Scale)
-Secondary outcomes
(1) Depression (Beck Depression Inventory)
(2) Stress (Physical stress, Psychological stress)
(3) Status anxiety
(4) Fatigue
Data statistics All sorts of values, such as mean, standard deviation, tand fvalues, calculated effect size
DSM-5 =Diagnostic and Statistical Manual of Mental Disorders-5, RCT=randomized controlled trial.
Cheong et al. Medicine (2021) 100:9 www.md-journal.com
3
(6) Sleeping measure
[36]
consists of 15 questions and is a 4-point
scale. It has a range of up to 60 points from a minimum of 15
points, and a higher score indicates better sleep.
2.6.2. The secondary outcomes. Secondary medical outcomes
reported were depression, stress, anxiety, and decreased fatigue.
They were assessed as follows;
(1) Change in the degree of depression as measured by validated
assessment tools such as the Hamilton Depression Scale
(HAMD)
[37]
and the Beck Depression Inventory (BDI).
[38]
(2) Stress was measured using the perceived stress scale
(PSS).
[39,40]
(3) Anxiety was measured using the State-Trait Anxiety
Inventory State version (STAI).
[41]
(4) Fatigue was measured using the fatigue symptom inventory
(FSI).
[42]
2.7. Study selection
Screening procedure is as follows. Domestic and international
online databases were searched. A total of 7924 articles, including
7200 articles registered with keywords of aromaand sleep
problemsfrom 2000 to 2019 and 724 additional articles from
other search sources, were collected. Among them, a total of 1240
papers that were duplicates and 5643 articles that were not
conducted on humans and subjects with sleep problems, were
excluded. A total of 21 articles on meta-analysis, including
systemic literature reviews and 659 studies on non-aroma
inhalation therapy were excluded from the remaining 1041
articles. A total of 301 studies that did not report improved sleep
and 26 articles that did not correspond to Participants, Interven-
tion, Control, Outcomes & Study Designfor the systemic literature
review were excluded.In the end, a total of 34 articles were selected
and numerical values were reported in all these articles. The meta-
analysis was performed and results were reported following the
PRISMA guidelines (Guidelines Flow Diagram).
[18]
2.8. Data coding extraction
Using a standardized data collection form, 3 independent
researchers cross-checked the data extraction process. Discrep-
ancies were resolved through discussion with other researchers.
The coding plate was constructed, as shown in Table 2, to analyze
the extracted data. The coding of data for this study was based on
a meta-analysis of various aromatherapy effects on the sleep
disorders reported by Hwang and Shin.
[3]
In addition, based on
the paper by Lillehei and Halcon,
[43]
basic information (author,
year, and title), method of intervention (direct or indirect
aromatherapy), and interventions (aroma type: single or mixed,
study group characteristics: general, patient, etc) were included in
the proceedings (total sessions, weekly sessions, session hours).
To ensure the reliability of the meta-analysis coding, one
researcher with experience in the meta-analysis, one researcher
with a major in applied statistics of research methodology and
meta-analysis, and one specialist from oriental neurological
psychiatry that used aromas to treat insomnia, were cross-coded
as well. During the course of coding, the paper, which showed no
consensus or required more conrmation, an expert on insomnia
was consulted. The coding analysis table is shown in Table 2.
2.9. Quality assessment of articles
Quality assessment of articles was conducted using Review
Manager version 5.3 software (Cochrane, London, UK), to assess
the risks of random selection, allocation concealment, blinding of
participants and personnel, blinding of outcome assessment,
incomplete outcome data, selective reporting, and other biases.
The risk was evaluated as low, high, and unclear.
[44]
2.10. Literature evaluation and sorting
Results from the included 34 papers following the systematic
literature reviewwere analyzed, encoded, and arranged into forms.
The forms included the selection of research design, number of
participants, criteria for participant selection and exclusion,
measurement variables and tools, result variables, and statistical
values. To ensure accuracy during the process, 2 researchers
independently conducted the evaluations, and the results were
cross-checked and compared for inter-rater agreement.
2.11. Meta-analysis
The data analysis procedure included the verication of
publication bias errors, verication of homogeneity and
Figure 1. Guidelines ow diagram.
Cheong et al. Medicine (2021) 100:9 Medicine
4
heterogeneity, calculation of total effect size, and meta-analysis of
variance (meta-ANOVA) for aromatherapy over time and period
of intervention (meta-ANOVA with aroma type, aroma single or
mixed/research group, and aroma direct and indirect effects). In
addition, the sizeof the calibration effect (Hedgeg) was used to give
weight to the number of cases studied. This required Hedge g to be
calibrated due to the intergroup effect size and Cohen dtends to
overestimate the effect size when the sample is small.
[45]
Finally, for
the analysis of the data, such as effectiveness size and homogeneity
verication, a statistical program for meta-analysis (Comprehen-
sive Meta-Analysis version 2.0 [Biostat Inc, NJ]) was used. All
analysis process was consulted by a meta-analysis expert.
2.12. Additional analyses
For additional analyses, meta-regression analysis was performed
using the primary and secondary outcomes as continuous
variables.
2.13. Ethics and dissemination
Ethical approval was not required because the data used in this
systematic review were not individual patient data; therefore,
there were no concerns regarding privacy.
3. Results
3.1. Quality assessment results
For the quality assessment of articles, there was a high risk of
bias in blinding of participants and personnel, which was a
performance bias, and in the allocation concealment and random
sequence generation, which were selection biases. Additionally,
an unclear risk of bias was observed for blinding of outcome
assessment, which was detection and other biases. However, low
risk was observed for incomplete outcome data and selective
reporting (Figs. 2 and 3).
3.2. Systematic literature review evaluation and sorting
results
The systemic literature review results are as follows. Among the
34 studies (Tables 3 and 4), 13 articles (37.2%) and 21 articles
(62%) used single and mixed aromas, respectively. Among the 13
articles that used single aroma oil for inhalation, lavender aroma
oil was used in 10 studies (76%). Additionally, lavender was used
in 16 papers that used mixed aromas. This nding suggests a bias
of oils related to sleep and it is necessary to assess why lavender
aroma improves sleep. A total of 3, 13, and 18 articles performed
indirect inhalation (necklace, etc), a mix of indirect and direct
inhalation, and direct inhalation, respectively. Tools used to
analyze main effects and evaluate improvements in sleep
disorders included the sleep scale A developed in Korea (9
studies), Pittsburg sleep quality index (4 studies), and Snyder-
Halpern and Verran
[46]
sleep scale (8 studies). Assessment of
secondary effects showed both decreased psychological problems
such as depression and anxiety, and the physiological functions,
including blood pressure and fatigue. As a result, the systematic
literature review demonstrated that aroma inhalation therapy
was benecial in improving sleep.
Table 2
Data coding extraction.
Variables Moderator
Outcomes Primary outcomes
Secondary outcomes
Kinds of aroma Single Lavender, phytoncide, rosemary,
Rosadamascence
Mixed Sweet orange, Rosewood marjoram
Ylang-Ylang, Bergamot, Basil exotic
Cymbopogon marini
Aniba rosaeodora, Roman Chamomile
Citrus bergamia
Grapefruit, Citrus paradisi,
Geranium, Neroli,
Citrus aurantium L. var
Subjects Cardiac diseases Patients with cardiac stents
The heart disease
Participants Patients Section Cesarean section
Colectomy, hysterectomy
pneumonectomy
Psychological disorders or problems Sleep disorders such as insomnia, sleep problems, anxiety disorder, schizophrenia
ETC. Pain patient, essential hypertension, patient undergoing hemodialysis
Coronary arteriography patient, patient in an intensive care unit
Non-patients
Job kind Night shift nurses, subway worker (night shift)
Nation Domestic Korea
Others
Inhalation Direct
Methods Indirect
Cheong et al. Medicine (2021) 100:9 www.md-journal.com
5
3.3. Publication bias analysis
The nal 34 selected papers, shown in Table 5 (effect size case =
273), were analyzed for publication bias. In this study, we
examined the publication bias (Figs. 2 and 3) of the papers
collected through the funnel plot (Fig. 4) and analyzed the bias of
the samples in a complementary manner using the estimation and
ll method. As shown in Figs. 5 and 6, the funnel plot is
somewhat symmetrical and had no issues with bias.
[47]
In
addition, sensitivity analysis, which is the estimation additive
(Trim & Fill) of the complementary methods of Duvall and
Tweedie,
[48]
resulted in the same calibration and observation
values of the coordinated study (Table 6).
3.4. Verication of homogeneity and overall effect size of
aroma inhalation effect on sleep problem
The results of the evaluation of the total effect size of
aromatherapy, calculated from 172 effect sizes culled from the
34 studies included in the present study, are shown in Table 4.
The homogeneity test was performed at a signicance level of
P<.05, resulting in the application of the random effect model,
which was determined to be heterogeneous by rejecting the null
hypothesis at 193.515 (P<.01).
[49]
The value of I, which
represents the ratio of the total variance contrast study, was
82.947, which is >50 and thus had signicant heterogeneity. In
addition, since each study was assessed differently by different
researchers, estimates of population effect size were not the same.
Therefore, the analysis reported in this paper was conducted
using a random-effect model, since the size of the effects assessed
by the researchers varied, and was statistically signicant through
heterogeneity analysis (Table 7). The total effect size for sleep
problems was 0.650 and the 95% condence interval for the total
effect size ranged from 0.542 to 0.757. This is equivalent to 73%
to 76% if the U-index, the cumulative distribution analysis
method of effect size, is presented. The effect size of 0.65 implies
that the control group showed 50% effectiveness in the
experiment, whereas the effectiveness ranged from 73% to
76% for the experimental group. Therefore, the experimental
group exceeded the median value of the control group (50% for
the control group) with a success rate of 73% to 76%. Thus, the
program effectiveness of the experimental group that used
aromatherapy for sleep problems can be interpreted as 23 to 26
higher than the program effectiveness of the control group
(Rosenthal and Rubin
[50]
). The criteria of Cohen
[51]
and
Wolf
[52,53]
were to interpret the magnitude of the effects assessed
in the meta-analysis. Cohen
[51]
interpreted the average effect size
(d) below 0.2 as a small effect size, 0.5 as a medium effect size,
and 0.8 as a large effect size. Wolf
[52]
has an educational
signicance if its effect size is >0.25. At least 5 studies, the criteria
for interpretation were presented as signicant at a practical and
therapeutic level. According to this criterion, the overall average
effect size of the aroma inhalation method for sleep problems was
0.65, which was greater than the middle effect size. Thus, the
groups that conducted the aromatherapy program had a more
signicant outcome on the overall average effect size compared
with those that did not (Fig. 5).
3.5. Effect sizes of secondary outcomes
After each classication for negative effects analysis, the
differences between each group, and the size of the effects were
veried. The effect size of each program was as follows:
stress (effect sizes [ES](g) =0.838, P<.01), (anxiety (g) =0.599,
P<.01), other (blood pressure, appetite, pain, etc) (ES(g) =0.592,
P<.01), (depression(g) =556, P<.01), and (fatigue(g) =0.544,
P<.01), demonstrating a statistically signicant effect size.
However, the differences in effects between the groups were not
statistically signicant. That is, even though inhalation of aromas
had a signicant effect on stress, anxiety, depression, and fatigue,
it did not exhibit a statistically signicant difference (Table 8).
Figure 2. Risk of bias included in the study.
Cheong et al. Medicine (2021) 100:9 Medicine
6
3.6. Effect size according to intervention factors
In the meta-analysis, the modulating effect analysis according to
the arbitrator more directly validated the difference in effect size
among subgroups and allowed the effect on the average effect size
to be veried through the study-level variables that describe the
effect size, that is, the covariates or modiers. In this study, we
attempted to determine the statistical signicance by conducting
differential verication and regression analysis for each variable.
3.7. Individual effect size and meta-ANOVA test of
category
3.7.1. The types of aroma (single or mixed). After classifying
the effects of single and compound aromas on sleep problems, the
differences between groups and their sizes were analyzed. The
difference in the size of the effects between the 2 groups (single
aromas vs composite aromas) was (ES(g) =0.720, P<in the case
of single aromas .01), and (ES(g) =0.576, P<.01) for composite
aromas; each effect size was statistically signicant. In addition,
the effect of using a single aroma was signicantly higher than
that of the composite aromas (Q=2.38(1) and P<.05) (Table 9).
3.7.2. Analysis of effect size based on types of study
subjects (clinical group and general [shift workers and
non-shift workers]). The clinical (ES(g) =0.782, P<.01) and
general groups (ES(g) =0.538, P<.01) (where the effect of the
inhalation of aromas was statistically signicant) exhibited a
statistically signicant inter-difference (Q(df) =6.759(1), P
<.05). This means that the aroma inhalation effect is also a
night shift in the general population (ES(g) =0.682, P<.01),
General (ES(g) =0.483, P<.01); each of the aroma inhalation
was statistically signicant for sleep but the difference between
groups in the general population was not signicant. This
means that aroma inhalation has varying effects on different
sleep disorders, without any signicant difference recorded
between the groups for shift workers or non-committal groups
(Table 10).
3.7.3. Analysis of effect size based on research duration of
the time and times. As a mediator, the size of the effect of aroma
inhalation on sleep problems was analyzed for 24 hours and before
bedtime (13 times), that is, if aroma was inhaled from 1 to 3 times
before bed (ES(g) =0.661, P<.01), or if a 24 hours aroma necklace
was worn or aroma was continuously inhaled using tools for
indirect inhalation (ES(g) =0.476; P<.01). This resulted in a
greater effect of premagnetic inhalation than a 24hours duration,
indicating a statistically signicant difference (Q(df)=5.637,
P<.05). Therefore, continuous inhalation of 1 to 3 times was
more effective than 24hours indirect inhalation for the ameliora-
tion of sleep problems, and that the differences in direct and indirect
inhalation, rather than the duration of time, elicited a change in the
size of the effects. In addition, after analyzing the effects of 1 to 3
cycles of inhalation before going to bed (the rst time was [ES(g)=
0.699 and P<.01], [ES(g)=0.645 and P<.01], the third [ES(g)=
0.534, P<.01]), each group showed a statistically signicant effect
but differences between groups were not statistically signicant.
Although there were differences in the effects of direct and indirect
inhalation methods, the session not resulting in a statistically
signicant change could be due to the size of the effects. Next, the
effectiveness of aroma inhalation in alleviating sleep problems was
analyzed on a national scale; Korea (ES(g)=0.724; P<.01) and
other countries (ES(g)=0.470, P<.01). A statistically signicant
difference (Q(df)=7.766, P<.01) was observed. This was also
observedin the SR analysis howeverthe studies of aroma inhalation
methods for improvement of sleep disorders orsleep problems were
statistically signicant compared with other countries. This
indicates that in Korea, there is an active study of the effect of
aroma inhalation onsleep disorders andsleep problems, andas well
as an interest in their efcacy. The results are shown in Table 5.
Figure 3. The risk of bias using RevMan.
Cheong et al. Medicine (2021) 100:9 www.md-journal.com
7
Table 3
Studies included in the systematic review and meta-analysis.
Ko, Ye Jung. Effects of lavender fragrance inhalation method on sleep, depression and stress of institutionalized elderly. Journal of East-West Nursing Research, 2012, 18.2:
7480.
Kim, O.J. The effect of aroma inhalation method on stress, anxiety and sleep pattern in patients undergoing hemodialysis. Unpublished masters thesis, Chung-Ang University,
Seoul, 2007.
Park, Sihyun, et al. The effect of aroma inhalation therapy on fatigue and sleep in nurse shift workers. Journal of East-West Nursing Research, 2012, 18.2: 6673.
Choi, Eun-Mi; Lee, Kyung-Sook. Effects of aroma inhalation on blood pressure, pulse rate, sleep, stress, and anxiety in patients with essential hypertension. Journal of Korean
Biological Nursing Science, 2012, 14.1: 4148.
Oh, Hyun-Mi; Jung, Geum-Sook; Kim, Ja Ok. The effects of aroma inhalation method with roll-on in occupation stress, depression and sleep in female manufacture shift
workers. Journal of the Korea Academia-Industrial cooperation Society, 2014, 15.5: 29032913.
Kim, WonJong; Hur, Myung-Haeng. Inhalation effects of aroma essential oil on quality of sleep for shift nurses after night work. Journal of Korean Academy of Nursing, 2016,
46.6: 769779.
Park, S., et al. The effects of aroma therapy on sleep disorder patients with musculoskeletal pain. J Oriental Rehab Med, 2010, 20: 215230.
Choi, Jae-won, et al. Phytoncide aroma inhalation and exercise combination therapy mood state, college life stress and sleep of college students. Journal of Digital
Convergence, 2016, 14.12: 633644.
Lee, Sun-Ok; Hwang, Jin-Hee. Effects of aroma inhalation method on subjective quality of sleep, state anxiety, and depression in mothers following cesarean section delivery.
Journal of Korean Academy of Fundamentals of Nursing, 2011, 18.1: 54.
Lee Gyeong-Jae. A Study on the Effect of Aroma on Sleep and Fatigue of Subway Crew. Graduate School of Glocal Integration at Sunmoon University: Natural healing studies
2018. Master thesis.
Choi Seo Yeon. (The) effects of aroma oil inhalation therapy on appetite, sleep, and stress in middle-aged overweight women: a randomized controlled trial. Graduate School of
Chung-Ang University: Graduate School of Nursing and Nursing Studies. 2016. Doctoral thesis.
Lee Sook-hyun. Effects of Aromatherapy on Stress Response, Sleep and Immunity in Middle-Aged Women. Graduate School of Eulji University: Nursing and Nursing Studies.
2018. Doctoral thesis.
Lee Yoo-jin. The Inhalation Effects of Aroma Essential Oil on Stress, Sleep Quality and Immunity of Shift work Nurses: A Parallel group Randomized Controlled Trial. Graduate
School of Clinical Nursing at Eulji University: Clinical nursing education major clinical nursing education. 2018. Master thesis.
Cho, M.Y. The effects of Aromatherapy on Anxiety, Vital sign & Sleep of PCI patients hospitalized in intensive care units. Unpublished masters, Eulji University, Daejeon, 2011.
Choi Myung-ja. The Effects of Aromatherapy on Alleviation of Stress Among Schipzophrenic Patients. Graduate School of Health at Chosun University: Alternative Medicine.
2006.
Lee, M. H. The effect of aroma therapy on the comfort, anxiety and sleep of heart stent spiled patients hospitalized in intensive care unit. Unpublished masters, Dong-A
University, Pusan, 2006.
Cho Eun-hee. The Effects of Aromatherapy on Stress, and Sleep Quality in ICU patients. Graduate School of Clinical Nursing at Eulji University: Clinical nursing education major,
clinical nursing education. 2017.
Lee Jin-kyung. The Effect of Aroma Inhalation on Fatigue and Sleep: Focused on Mothers with Preschool Children. Graduate School of Alternative Medicine at Kyunggi
University: A major in alternative medicine and psychiatric treatment. 2017.
Min Kyung-min. The effect of inhaling orange, lavender and chamomile roman aromas on the quality of sleep and fatigue of shift working nurses. Chung-Ang University
Graduate School: Graduate School of Nursing and Nursing Studies. 2015.
Kim Hye-yeon. (The) effect of aromatheray on anxiety and sleep of patients with coronary angiography. Dankook University Graduate School: Graduate School of Nursing and
Clinical Nursing in 2008.
So Hae-Ran. The Effect of Aroma Inhalation on Pain, Anxiety, Vital Sign and Sleep of Patients with Colon Resection. Gachon University Graduate School of Nursing: Senior
Nursing Education. 2012.
Choi Jeong-hee. Effects of Aroma Inhalation Therapy on Pain, Stress, Nausea·Vomiting and Sleep of Patients Following a Hysterectomy. Graduate School of Gachon University:
Nursing for the Elderly 2013.
Lee Won-jin. Effects of Aroma Inhalation to Blood Pressure, Pain and Quality of Sleep in Patients with Pulmonary Resection. Graduate School of Ewha Womens University:
Department of Nursing Science. 2016.
Jeon WhaYoung. Aromatherapy effects on sleep improvement and depression in middle-aged women. Chosun University: Alternative Medicine, 2015.
Nam Jung-ja. Effects of aromatherapy and massage on sleep disturbance and problematic behaviors on elderly with dementia. Graduate School of Ewha Womans University:
Department of Nursing Science, 2008.
Lillehei, Angela Smith, et al. Well-being and self-assessment of change: Secondary analysis of an RCT that demonstrated benet of inhaled lavender and sleep hygiene in
college students with sleep problems. Explore, 2016, 12.6: 427435.
Nematolahi, Pouya, et al. Effects of Rosmarinus ofcinalis L. on memory performance, anxiety, depression, and sleep quality in university students: a randomized clinical trial.
Complementary therapies in clinical practice, 2018, 30: 2428.
Lee, Mi-kyoung, et al. The effects of aromatherapy essential oil inhalation on stress, sleep quality and immunity in healthy adults: Randomized controlled trial. European Journal
of Integrative Medicine, 2017, 12: 7986.
Afshar, Mahnaz Keshavarz, et al. Lavender fragrance essential oil and the quality of sleep in postpartum women. Iranian Red Crescent Medical Journal, 2015, 17.4.
Lee, Sung-Hee. Effects of aroma inhalation on fatigue and sleep quality of postpartum mothers. Korean Journal of Women Health Nursing, 2004, 10.3: 235243.
Hajibagheri, Ali; Babaii, Atye; Adib-hajbaghery, Mohsen. Effect of Rosa damascene aromatherapy on sleep quality in cardiac patients: a randomized controlled trial.
Complementary therapies in clinical practice, 2014, 20.3: 159163.
Karadag, Ezgi, et al. Effects of aromatherapy on sleep quality and anxiety of patients. Nursing in critical care, 2017, 22.2: 105112.
Goel, Namni; Kim, Hyungsoo; Lao, Raymund P. An olfactory stimulus modies nighttime sleep in young men and women. Chronobiology International, 2005, 22.5: 889904.
Moeini, Mahin, et al. Effect of aromatherapy on the quality of sleep in ischemic heart disease patients hospitalized in intensive care units of heart hospitals of the Isfahan
University of Medical Sciences. Iranian journal of nursing and midwifery research, 2010, 15.4: 234.
Cheong et al. Medicine (2021) 100:9 Medicine
8
3.8. Additional analysis
3.8.1. A regression analysis of the main effects and sub-
effects of the aroma inhalation period. For each study, the
effect size was analyzed according to the total number of sessions
and was reanalyzed after the number of aroma inhalation
sessions was coded as a continuous variable. As a result, the slope
(b=) in the main effect size (0.00367, P<.01) was statistically
signicant (Intercept: 0.50136, P<.01) (t=0.13179, P<.01).
These results show that the effect increases as the total number of
sessions increases. In addition, the slope (b=) in the regression
analysis of the size of the negative effects (0.00405, P=.01) and
intercept (0.47506, P<.01) was statistically signicant (t=
0.24879; P<.01). This shows that the impact of the negative
effects also increased as the total number of sessions increased.
The regression results for assembly acquisition are the same as
those outlined in Table 11 and Figs. 6 and 7.
4. Discussion
Sleep disorders, including insomnia, are one of the most common
diseases that affect people in the current modern society.
[54,55]
Persistent sleep deprivation leads to the consumption of sleep
inducers and sleeping pills.
[56,57]
However, some of these drugs tend
to lead to overdose and addiction, and the sleep symptoms from the
drugs persist can until the next day, impacting daily life activities.
[8]
As a result, discussions on various alternative treatments such as
aromatherapy have recently gained attention.
[21]
When the aroma is
inhaled, the aroma molecules enter the olfactory epithelium through
the nasal roof and stimulate the olfactory neurons. This leads to the
secretion of hormones in the pituitary gland as well as peptides.
[17]
In
particular, endorphin, which is one of the secreted peptides, is
effective for treating sleep disorders caused by depression and
anxiety,andinreducingpainandchronicstress.
[58]
This study conducted a systematic literature review and meta-
analysis to assess the clinical efcacy of aroma inhalation therapy
in the treatment of sleep problems in patients diagnosed with
insomnia, using published reports until June 2019. Previous
studies that analyzed the effects of aroma on sleep problems were
mostly conducted with massage therapy in parallel.
[3]
However,
massage therapy requires help from someone else and there is a
limit on it being performed alone.
[59]
Therefore, this study
analyzed studies that assessed the aroma inhalation therapy as the
sole manner for reducing sleep problems without much effort and
help from anyone else.
Figure 4. Funnel plot of the publication bias.
Cheong et al. Medicine (2021) 100:9 www.md-journal.com
9
Table 4
Systematic literature review evaluation and sorting results.
Study (year) Aroma (single/mixed) Application Research design Nation Samplesize (n) Primary outcome Secondary outcome Subject character
1. Ko (2012) Lavender (single) Direct inhalation Equivalent control /RCT Korea. 39 (exp: 18, cont: 21) Korea Sleep Scale A(+) Depression()
Stress()
An elderly person living in a
facility
2. Kim et al (2007) Lavender, sweet orange
2:1 (Mixed)
Direct inhalation Equivalent control /RCT Korea. 50 (exp: 25, cont: 25) Korea Sleep Scale A(+) Stress ()
Anxiety()
Chronic hemodialysis
patients
3. Park et al (2007) Lavender, Rosewood 1: 1
(Mixed)
Direct inhalation Nonequivalent control
/RCT
Korea. 60 (exp: 30, cont: 30) Sleep Quality Scale(+) Fatique() Nurse Shift Workers
4. Choi et al (2012) Lavender Marjoram, Ylang-Ylang
4: 3: 3 (Mixed)
Direct inhalation Equivalent control /RCT Korea 36 (exp: 20, cont: 16) Sleep state()
SleepSatisfaction(+)
Stress()
Anxiety()
Patients with essential
hypertension
5. Oh et al (2014) Bergamot, Lavender, Ylang-
Ylang, Jojoba oil 1: 1: 1: 1
(Mixed)
Inirect inhalation Nonequivalent control
group/RCT
Korea 52 (exp: 26, cont: 26) Korea Sleep Scale A(+) Depression()
Job stress()
Female production workers
6. Kim et al (2016) Lavender Direct and indirect
inhalation
Nonequivalent control
group/RCT
Korea 60 (exp: 30, cont: 30) -Quality of Sleep [QOS](+)
-[NRS])(+) [VSH](+)
-([NoA])(+)
Night shift nurse
7. Park et al (2010) Lavender, Vergamot, Basil exotic
2: 2: 1 (Mixed)
Direct and indirect
inhalation
Equivalent control
group
Korea 60 (exp: 30, cont: 30) Korea Sleep Scale A(+) Patients with
musculoskeletal pain
8. Choi et al (2016) Phytoncide Direct inhalation RCT Korea 34 (exp: 14, cont: 20) Korea Sleep Scale A(+) -College Life Stress()
-Feeling Scale L FS
University students
9. Lee et al (2011) Lavender Direct inhalation Nonequivalent control
group /RCT
Korea 67 (exp: 33, cont: 34) Korea Sleep Scale A(+) (State-Trait Anxiety Inventory()
Depression ()
Cesarean section mother
10. Lee (2018) Cymbopogon marini, Aniba
rosaeodora, Citrus bergamia
1: 1: 1 (Mixed)
Direct inhalation Nonequivalent control
Group /RCT
Korea 60 (exp: 30, cont: 30) -Quality of Sleep [QOS] (+) Japan Society for Occupational
Health (Fatique)()
Subway crew in shift work
11. Choi (2016) Grapefruit, Citrus paradisi,
Geranium, Neroli 4: 2: 3
(Mixed)
Direct inhalation RCT Korea 54 (exp: 27, cont: 27) -Quality of Sleep [QOS](+) (Synder
Halperm Verran: VHS)
VSH sleep scale(+)
-Visual analog scale: (VAS)(
NPY/ GLP-1
Overweight middle-aged
woman
12. Lee (2018) Lavender, Ylang-Ylang, Marjoram
4: 1: 5 (Mixed)
Direct inhalation/Indirect
inhalation
RCT Korea 62 (exp: 31, cont: 31) Verran & Synder-Halpern Sleep (+) -Subjective stress response
(NRS)()
-Physiological stress response()
A middle-aged woman
13. Lee (2018) Lavender, Ylang-Ylang, Neroli 4:
2: 1 (Mixed)
Direct inhalation RCT Korea 63 (exp: 31, cont: 32) -Quality of Sleep [QOS](+)
- NRS (Numeric Rating Scale)(+) -VSH
-(Actigraph[63])
-(Turbidimetric Immnuassay, TIA)
Stress()
-NRS (Numeric Rating Scale)
-Serum cortisol levels
Night shift nurse
14. Cho (2011) Lavender, Roman Chamomile,
Neroli
2: 1: 0.5 (Mixed)
Direct inhalation Non-equivalent control
group pretest-/RCT
Korea 56 (exp: 28, cont: 28) -VSH (Snyder-Halpern and Verran )
[46]
Sleep Scale
Anxiety
-(STAI-KYZ)
-Blood pressure
Patient with cardiac stent
intubation
15. Choi (2011) Roman Chamomile, Lavender,
Marjoram, Sandalwood
3: 2: 1: 1 (Mixed)
Direct inhalation Non-equivalent control
group /RCT
Korea 74 (exp: 37, cont: 37) Korea Sleep Scale A(+) Stress()
PWI(+)
Schizophrenic
16. Lee (2006) Lavender, Roman Chamomile
2: 1 (Mixed)
Direct inhalation/Indirect
inhalation
Nonequivalent control
Group/RCT
Korea 40 (exp: 20, cont: 20) -VSH(+) -Comfort
General comfort questionnnaire
-Anxiety ()
Patient with cardiac stent
intubation
17. Cho (2017) Lavender Direct inhalation Nonequivalent
control Group/RCT
Korea 60 (exp: 30, cont: 30) -VSH(+) -Subject Stress
-NRS()
- (Stress Index [S.I])
- (Blood pressure)
Clinical pulmonary infection
score
18. Lee (2016) Bergamot, Lavender, sweet
Majoram
1: 2: 1 (Mixed)
Direct inhalation/Indirect
inhalation
Nonequivalent control
group /RCT
Korea 40 (exp: 19, cont: 20) -VSH(+) -Fatique (Japan Society for
Occupational Health)
General
19. Min (2015) Korea 60 (exp: 30, cont: 30) -Quality of Sleep [QOS](+) Night shift nurse
(continued )
Cheong et al. Medicine (2021) 100:9 Medicine
10
Table 4
(continued).
Study (year) Aroma (single/mixed) Application Research design Nation Samplesize (n) Primary outcome Secondary outcome Subject character
Sweet Orange, Lavender,
Chamomile
Direct inhalation/Indirect
inhalation
Nonequivalent control
Group /RCT
-Fatigue (japan Society for
Occupational Health)
20. Kim (2008) Bergamot, Lavender, Ylang-
Ylang, 3: 3: 1 (Mixed)
Direct inhalation/Indirect
inhalation
Non-equivalent control
group /RCT
Korea 39 (exp: 18, cont: 18) -VSH(+)
-Sleep satisfaction (VAS)[66]()
-Anxiety () Coronary angiography
patients
21. So (2012) Lavender, Sweet Orange,
Meichang: 2: 1: 1 (Mixed)
Direct inhalation/Indirect
inhalation
Nonequivalent control
group/RCT
Korea 70 (exp: 35, cont: 35) Visual Analogue Scale: VAS() -Pain () (VisualAnalogue Scale:
VAS)
-Anxiety()
-Vitals signal
The paitients done colon
resection
22. Choi (2013) Lavender, Mandarin, Majoram
3: 2: 1 (Mixed)
Direct inhalation/Indirect
inhalation
Nonequivalent control
group/RCT
Korea 60 (exp: 30, cont: 30) -Korea Sleep Scale A(+)
-VAS()
-Pain()/-Stress ()
-Cotisol
-Index of nausea vomiting &
retching
Hysterectomy patient
23. Lee (2016) Chamomile, Sweet Orange
1: 2 (Mixed)
Direct inhalation/Indirect
inhalation
RCT Korea 53 (exp: 27, cont: 26) -VSH(+) -Pain() Pneumonectomy
24. Jeon (2014) Argan Oil, sweat almond oil
Lavender geranium,
Chamaecyparis obtusa
essence (not information)
Direct inhalation/Indirect
inhalation
RCT Korea 19 (exp: 12, cont: 7) -Korea Sleep Scale A(+)
-VAS()
-Depression() Middle women
25. Nam (2007) Lavender Direct inhalation/Indirect
inhalation
RCT Korea 36 (exp: 18, cont: 18) -Researcher devised sleep disorder
observation record ()
Problem behavior measurement
(Kim, 2003
[66]
)
26. Lillehei et al (2016) Lavender Direct inhalation RCT USA 76 (exp: 38, cont: 38) -PSQI (Pittsburgh Sleep Quality Index)
()
-Self Assessment of Change
Questionair (not.sig)
College students with sleep
problems
27. pouya Nematolahi
et al (2018)
Rosemary Direct inhalation RCT IRAN 68 (exp: 34, cont: 34) -PSQI (Pittsburgh Sleep Quality Index)
()
-HAS()
_HAD()
-Memory (not sig.)
General
28. Lee et al (2017) Lemon, eucalyptus, tea tree,
peppermint
4: 2: 2: 1 (Mixed)
Direct inhalation RCT Kor 60 (exp: 30, cont: 30) -QOS()
-time of sleep(+)
-Stress Index()
-Depression()
General
29. Mahnaz et al
(2015)
Lavender Direct inhalation RCT IRAN 158 (exp79, cont: 79) QOS
30. Lee (2004) Lavender, eucalyptus
Not information
Direct /Indirect
inhalation
RCT Kor 51 (exp25, cont: 26) QOS()
-SHV(+)/-VAS()
-Rhoten Fatique()
31. Ali, et al (2014) Rosa damascence Indirect inhalation RCT IRAN 60 (exp30, cont: 30) PSQI() Cardiac patients
32. Ezgi, et al (2017) Lavender Indirect inhalation RCT Turkey 60 (exp30, cont: 30) PSQI() -BAI() Sleep disorder and anxiety
patietns
33. Namni, et al
(2005)
Lavender Direct inhalation RCT USA 31 (exp16, cont: 15) Stanford Sleepiness Scale()
-The Prole of Mood State
Questionnaire()
General
34. Mahin, et al (2010) Lavender Direct inhalation RCT IRAN 64 (exp32, cont: 32) QOS() General
Cheong et al. Medicine (2021) 100:9 www.md-journal.com
11
The results are as follows: rst, lavender was used as the
aromatic oil in most of the studies. In both types of studies that
used single aromatic oil and mixed oils, lavender was used most
widely used. As reported by studies,
[60,61]
lavender makes the
body feel heavy and provides a sense of stability, also, because of
its natural sedation, lavender balm is an example of Western folk
medicine that solves the problem of insomnia using a pillow lled
with lavender, which may be the reason for its usage in most
studies.
Additionally, the quality assessment of studies showed that
there was a high risk for performance and selection bias. This was
because specic descriptions of research subject assignment and
randomization were not described in the studies. Further studies
to correct for these biases are necessary. Moreover, unclear risk of
detection bias was observed; however, there was no specic
report on the blinding of outcome assessment. Thus, as
mentioned in previous studies, outcome assessment must be
conducted carefully on studies regarding aroma.
[17]
Second, the
meta-analysis results are as follows. No statistically signicant
publication bias was observed in the studies. However, lavender
was used in most studies, as seen in the systematic review results.
This suggests that lavender may be the preferred aroma oil for
sleep; however, there may be differences in the commercially
available aroma.
[62]
Therefore, qualitative research on aroma-
therapists is recommended.
Analysis of effect size showed that the effect size of aroma
inhalation therapy in primary and secondary outcomes was
greater than the medium effect size, which indicates signicant
outcomes. Additional analysis was performed to assess the
difference in effects by comparing the single and complex mixed
aromas. As a result, the effects of a single aroma were greater than
those of the mixed aroma. This nding is consistent with previous
Table 5
Effect size based on research duration of the time and times.
Variables KES (g) SE 95% CI PQ
B
(df)
Inhalation time
24 hours 32 0.476 0.060 0.3580.594 .000 5.637 (1)
Before sleep 139 0.661 0.049 0.5640.758 .000
The number of aroma inhalation
1 104 0.699 0.059 0.5830.816 .000 3.504 (2)
2 10 0.645 0.154 0.3440.946 .000
3 25 0.534 0.073 0.3900.678 .000
N ES (g) SE 95% CI P
Nation
Korea 25 0.724 0.071 0.5860.863 .000 7.766
∗∗
(1)
the others 9 0.470 0.058 0.3570.583 .000
CI =condence interval; ES =effect sizes; K=the number of effect sizes; P=P-value; Q
B
=difference verication between groups; SE=standard error.
P<.05.
∗∗
P<.01.
Figure 5. Forest plot of the aroma inhalation therapy.
Table 6
Result of the Trim and Fill.
Studies trimmed ES
c
95% CI Q
Observed values 0.64971 0.542240.75719 193.51456
Adjusted values 0 0.64971 0.542240.75719
CI =condential interval; ES =effect sizes; K=the number of effect sizes; Q
B
=difference verication
between groups; SE =standard error.
Cheong et al. Medicine (2021) 100:9 Medicine
12
Table 7
Validation of the homogeneity and effect size of the primary outcomes.
Model N KES (g) U(%) 95% CI Q(df) I
2
Fixed 34 172 0.593 82.86 0.5510.636 193.515(33) 82.947
∗∗
Random 34 172 0.650 84.05 0.5420.757
CI =condential interval; ES =effect sizes; K=the number of effect sizes; Q
B
=difference verication between groups; SE=standard error.
P<.05.
∗∗
P<.01.
Table 8
The effect size of secondary outcomes.
Secondary outcomes K(%) ES (g) SE 95% CI PQ
B
(df)
Stress 30 0.838 0.154 0.5351.140 .000 2.913(4)
Anxiety 10 0.599 0.138 0.3280.869 .000
ETC (blood pressure, appetite, pain) 27 0.592 0.081 0.4340.750 .000
Depression 6 0.556 0.116 0.3290.783 .000
Fatigue 10 0.544 0.089 0.3700.719 .000
CI =condence interval; ES =effect sizes; K=the number of effect sizes; P=P-value; Q
B
=difference verication between groups; SE=standard error.
Table 9
The effect sizes of aroma types (single or mixed).
K(%) ES (g) SE 95% CI PQ
B
(df)
Single 59 (34.5%) 0.720
∗∗
0.081 0.5610.879 .000 2.38
(1)
Mixed 112 (65.5%) 0.576
∗∗
0.047 0.4840.667 .000
CI =condence interval; ES =effect sizes; K=the number of effect sizes, P=P-value, Q
B
=difference verication between groups, SE=standard error.
P<.05.
∗∗
P<.01.
Table 10
Effect size based on types of study subjects (clinical group and general [shift workers and non-shift workers]).
K(%) ES (g) SE 95% CI PQ
B
(df)
Clinical group 60 0.782 0.083 0.6200.944 .000 6.759 (1)
General 111 0.538 0.044 0.4520.624 .000
Non-night shift workers 76 0.483 0.039 0.4070.559 .000 3.186 (1)
Night shift workers 35 0.682 0.104 0.4770.886 .000
CI =condence interval two dependent; ES=effect sizes; K=the number of effect sizes, Q
B
=difference verication between groups, SE=standard error.
P<.05.
∗∗
P<.01.
Table 11
A regression analysis of the main effects and sub-effects of the aroma inhalation period.
SE 95% CI +95% CI Zt
2
b0.00367 0.00103 0.00166 0.00568 3.57951 0.13179
∗∗
Intercept 0.50136 0.04030 0.42237 0.58035 12.44002
b0.00405 0.00119 0.00173 0.00638 3.41241 0.24879
∗∗
Intercept 0.47506 0.04471 0.38743 0.56269 10.62532
CI =condence interval; SE =standard error; Z =value of standard normal deviate.
P<.05.
∗∗
P<.01.
∗∗∗
P<.001.
Cheong et al. Medicine (2021) 100:9 www.md-journal.com
13
Figure 6. The regression analysis of aroma therapy program according to years about for the slope of the primary outcome.
Founded studies Through a database
search
(n = 7,200 )
Screening Included Eligibility Identification
Additional records identified
through other sources
(n =724 )
Records after duplicates and articles unrelated
sleep problem removed (n =1,041)
Records screened
(n =361)
Records excluded
(n = 301)
Full-text articles assessed
for eligibility
(n = 60 )
Full-text articles excluded,
with reasons
(n =26)
Studies included in
qualitative synthesis
(n = 34 )
Studies included in
quantitative synthesis
(meta-analysis)
(n =34 )
Figure 7. The regression analysis of aroma therapy program according to years about for the slope of secondary outcome.
Cheong et al. Medicine (2021) 100:9 Medicine
14
reports,
[63]
indicating that a single aroma is more effective for
treating sleep problems. Moreover, the effects of aroma
inhalation were greater in those experiencing sleep disorders
compared with those that complained of general sleep problems.
This nding demonstrates that aroma inhalation therapy may
play a role as a complementary and alternative method. As a
result, it was estimated that aroma inhalation therapy would be
effective not only for sleep disorders but also for patients
suffering from various psycho-emotional disorders and severe
diseases such as cancer, in the same context as stated in previous
studies.
[6466]
This study aimed to identify signicantly greater
effects among aroma inhalation time and frequency, and the
following are the results of the analysis of aroma inhalation
methods. It was observed that the effects were the greatest before
falling asleep and that there was no difference in the frequency of
aroma inhalation. Thus, it is recommended that lavender oil be
used for direct inhalation before sleep to solve sleep problems in
the future.
The limitations of the current study are as follows. First, this
study was conducted on papers published until June 2019, and
studies published in 2020 were not included. This was done to
analyze the results of 10 years. Therefore, a meta-analysis
including papers published from late 2019 to the present of
2020 is recommended. Second, the method was limited to the
inhalation of aroma oils, and methods such as massage were
excluded. This w as to help those experiencing sl eep problems nd
an effective self-method that is not restricted by time and place.
Therefore, future studies on the analysis of various intervention
methods using aroma in addition to inhalation methods are
recommended. Third, this study was only conducted on aroma
oils and therefore a comparative advantage analysis could not be
performed. Future studies that can conduct network meta-
analysis for comparative advantage analysis are recommended.
Fourth, lavender aroma oil was used in most of the selected
studies. It is highly likely that aroma experts and researchers
judged that the unique scent of lavender to be optimal for
providing mental and physical stability related to sleep.
However, the specic reason for the use of lavender could not
be addressed in the current study. Therefore, further qualitative
studies on the selection of lavender oil are necessary. Nonethe-
less, the ndings of this study may be used as basic dat a to create a
program that will help reduce sleep problems using aroma oils in
the future.
5. Conclusion
The quality assessment of studies demonstrated a high risk of
performance bias and selection bias. Unclear risk of detection
bias was observed; however, there was no specic report on
blinding of assessment outcomes. Lavender was the most used
aroma oil related to sleep. The intervention method was mainly
direct inhalation and secondary outcomes such as stress, anxiety,
and depression were evaluated. Meta-analysis showed that the
effects of aroma inhalation therapy were signicant in mediating
sleep problems. Additionally, the evaluation of secondary
outcomes showed that it had a signicant effect size in reducing
the stress emotion, anxiety, and depression. In detail, aroma
inhalation therapy with single oil was more benecial before
going to sleep for insomnia patients rather than those with
general sleep problems. Finally, primary and secondary outcome
analyses demonstrated that the effects increased signicantly as
the number of therapy sessions increased.
Author contributions
Conceptualization: Moon Joo Cheong.
Data curation: Moon Joo Cheong, Hyung Won Kang.
Formal analysis: Moon Joo Cheong.
Investigation: Moon Joo Cheong.
Project administration: Moon Joo Cheong, Hyung Won Kang.
Resources: Moon Joo Cheong, Hyung Won Kang.
Supervision: Moon Joo Cheong, Hyung Won Kang.
Writing original draft: Moon Joo Cheong, Hyung Won Kang.
Writing review & editing: Moon Joo Cheong, Hyung Won
Kang, Sungchul Kim, Jee Su Kim, Byeonghyeon Jeon,
Hyeryun Lee, Yu Ra Lee, Yeoung-Su Lyu.
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16
... 25 Various application methods of EOs, such as inhalation, massages, and baths, are reported to have positive effects on sleep quality. 24,26,27 Inhalation is the most popular and is often associated with EOs, 28 Inhaling essential oils is a quick, easy, and safe method. 29,30 Among the EOs, Lavender essential oil (LEO) is highly recommended due to its potential sleeppromoting effects. ...
... 29,30 Among the EOs, Lavender essential oil (LEO) is highly recommended due to its potential sleeppromoting effects. 28 LEO demonstrates positive effects on various clinical issues (e.g., anxiety, depression, fatigue, stress, and pain), and may potentially improve sleep quality and mood. 31,32 However, there is a lack of research evaluating the effects of LEO inhalation on sleep quality, mood states, and subjective feelings of recovery, specifically in athletes. ...
... Participants were asked to inhale the aroma of the LEO for 10 min, engaging in normal breathing, at their convenience prior to bedtime. 28 Sleep hygiene education session All participants attended a SHE session led by a specialist in sleep research and athletic recovery. The session took place one day prior to the start of the study and lasted for approximately 40-45 min. ...
Article
Background Sleep hygiene education (SHE) and lavender essential oil (LEO) inhalation are two effective strategies aimed at enhancing sleep quality and mood states. This study investigated the effects of a single SHE session combined with nightly LEO inhalation for 7 days of late-evening resistance training sessions on sleep quality and mood states in trained athletes. Methods Forty-two athletes were randomly assigned to four groups: a control group (CG), a SHE group (SHEG), a LEO group (LEOG), and a SHE + LEO group (CSLG). CG and LEOG maintained their sleep habits during the intervention, while SHEG and CSLG followed SHE recommendations. Additionally, LEOG and CSLG inhaled LEO nightly before sleep. Sleep patterns were recorded via actigraphy. The Brunel Mood Scale and the Hooper questionnaires were completed before and after the intervention. Results Sleep latency was lower in SHEG (p=0.001) and CSLG (p=0.012) compared to the CG. The subjective sleep score improved in SHEG, LEOG, and CSLG (p < 0.001), with greater improvement observed in SHEG (p = 0.002) and CSLG (p < 0.001) compared to CG at post-intervention. Additionally, significant improvements were observed in the Hooper index in the SHEG (p=0.048) and CSLG (p=0.027), with CSLG demonstrating higher scores compared to CG at the post-intervention assessment (p=0.026). Furthermore, the subjective fatigue score significantly decreased in the CSLG (p=0.009). Conclusions Combining SHE and LEO inhalation could be an effective strategy to enhance sleep latency, subjective sleep quality, and overall wellness, and reduce feelings of fatigue in trained athletes following late-evening resistance training sessions.
... In addition to its antifungal, antibacterial [3][4][5] cholinergic, relaxing [2] and antidepressant [7] properties, which have been exten studied, lavender has an important effect on both the cardiovascular system and the agement of blood glucose levels. Preclinical and clinical studies indicated that the u lavender essential oil can lower blood pressure [10,14] and improve coronary circu by reducing aortic cholesterol content and atherosclerotic plaque formation, thus pr ing an antiatherogenic effect [11,12] Furthermore, the well-known antioxidant prop of lavender oil and solid waste were confirmed by the high phenolic content and an dant capacity of the extract and dried extract determined in this research work. ...
... In addition to its antifungal, antibacterial [3][4][5], anticholinergic, relaxing [2] and antidepressant [7] properties, which have been extensively studied, lavender has an important effect on both the cardiovascular system and the management of blood glucose levels. Preclinical and clinical studies indicated that the use of lavender essential oil can lower blood pressure [10,14] and improve coronary circulation by reducing aortic cholesterol content and atherosclerotic plaque formation, thus providing an antiatherogenic effect [11,12] Furthermore, the well-known antioxidant properties of lavender oil and solid waste were confirmed by the high phenolic content and antioxidant capacity of the extract and dried extract determined in this research work. ...
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Background/objectives: Lavender has been utilized for its medicinal properties since ancient times, with numerous health benefits reported. This study aimed to valorize solid waste from lavender essential oil production by developing a novel lavender extract from solid lavender residues. The extract's preclinical safety and efficacy were evaluated with emphasis on plasma lipid and lipoprotein metabolism, glucose tolerance, and adipose tissue metabolic activity. Methods: Male C57BL/6 mice were divided into four groups of five mice each and fed for 30 days with lavender extract encapsulated in 10% maltodextrin, mixed with a standard chow diet. The first group (Lav 1×) received 21.1 mg/kg/day, the second group (Lav 10×) received 211 mg/kg/day, and the third group (Lav 100×) received 2110 mg/kg/day. A placebo group consumed the standard diet without lavender extract. Key outcomes included plasma lipid and lipoprotein profiles, transaminase levels, HDL antioxidant and anti-inflammatory potential, glucose tolerance, and mitochondrial activity in white (WAT) and brown (BAT) adipose tissues. Results: The novel lavender extract induced dose-dependent improvements in lipid and lipoprotein metabolism, glucose tolerance, and adipose tissue activity. The 2110 mg/kg dose (100×) demonstrated the most significant beneficial effects, although it was associated with a slight elevation in hepatic transaminase levels, indicating potential mild hepatic stress. Conclusions: Overall, the novel lavender extract exhibits promising health benefits with no major safety concerns at the tested doses, supporting its potential for therapeutic applications.
... Since the properties and therapeutic effects of lavender EO have been extensively investigated in both animals [23,24] and humans [25][26][27][28][29][30][31][32][33][34] to prove that its use indeed reduces anxiety, increases calmness and relaxation, and aids sleep, it was proposed to examine its potential application more specifically in pregnant women. ...
... Overall, the results obtained from the review covered a total of 413 pregnant women recruited for the six clinical trials, which may be a small number to reach conclusions beyond the specific conditions of each of the studies. It is worth noting, though, that the results found are consistent with other groups, i.e., there are many other scientific studies in the non-pregnant population that demonstrate the effectiveness of lavender EO in relieving stress, reducing anxiety, and alleviating insomnia [26][27][28][29][30][31][32][33][34]. ...
Article
Full-text available
Background/Objectives: During pregnancy, women can experience stress, anxiety, and insomnia, which affect their health and wellbeing. Since many conventional medications are contraindicated for pregnant women, there is a need to find alternative therapies for alleviating their discomfort. Lavender essential oil (EO) is recognized for its calming and relaxing properties; therefore, our goal was to review current knowledge of lavender EO use to reduce anxiety and stress as well as to improve sleep quality in pregnant women. Methods: We conducted a comprehensive literature search in 11 databases that included clinical trials published between 2000 and 2022. Results: Of the 251 articles found, only 6, comprising a total of 413 participants that used lavender EO during the second or third trimester of pregnancy, met the inclusion/exclusion criteria. One trial measured sleep quality, one measured anxiety, two measured both anxiety and stress, and two measured only stress. All studies reported significant (at least p < 0.05) improvement in the respective conditions and no adverse effects. Conclusions: The results obtained suggest that although the use of lavender EO during pregnancy has shown to have certain efficacy, given the small number of participants and lack of strong scientific literature, more studies are needed to provide further evidence on this topic.
... In South Korea, aromatherapy is attracting attention for its reported effectiveness in improving sleep in people with insomnia. According to a meta-analysis, single aromatherapy was more effective than mixed aromatherapy, and lavender oil therapy was the most effective, particularly in older adults with insomnia [17]. Additionally, physical activity is known to significantly affect sleep quality in old-old people. ...
... Non-pharmacological intervention programs developed for the elderly are mostly single-intervention programs such as aromatherapy [17], followed by laughter therapy, insomnia intervention programs, acupuncture therapy, and exercise therapy [14]. Based on the results of the literature review, the Good Sleep Program in this study comprised a multimodal intervention form that included sleep education, walking exercises, and aroma inhalation. ...
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Purpose: This study evaluated the effect of the a good sleep program on sleep quality, stress, and functional health in old-old women, that is women over the age of 75 years, who had insomnia. Methods: This quasi-experimental study used a non-equivalent control group pretest-posttest design. The participants were 35 old-old women with insomnia: 18 in the experimental group and 17 in the control group. Data were collected from August 24 and October 12, 2020. The experimental group, participated in a six-session good sleep program consisting of multiple components, including sleep health education, aromatherapy (lavender scent inhalation), abdominal breathing, sleep hygiene, and walking exercises was conducted. The Good Sleep Program was developed based on Cox’s interaction model of client health behavior. The control group received only a booklet on good sleep. The scales used for pre and post-intervention measurements were the Pittsburgh Sleep Quality Index, Perceived Stress Scale, and Functional Health Pattern Assessment Screening Tool. Results: Compared to the control group, the experimental group exhibited significant improvements in the quality of sleep (t=-3.92, p <.001), perceived stress (t=-3.35, p =.002), and functional health (t=2.97, p =.005). Conclusion: The Good Sleep Program can be used to reduce stress and improve sleep and overall health in old-old women.
... These processes are associated with angiogenesis and metastasis, underscoring their potential as therapeutic targets [20]. Conversely, MMP7 expression increases in later stages of colon cancer and correlates with poor prognosis [21,22]. Our findings suggest that during CRC progression, SMARCA1 regulates preprint (which was not certified by peer review) is the author/funder. ...
Preprint
Emerging evidence indicates that aberrations in the writing, reading, or erasure of chromatin modification codes are pivotal events in various human cancers. In this study, we conducted a systematic investigation of histone modification recognition proteins in a pair of colorectal cancer cell lines, SW480 and SW620. Using chromatin fractionation combined with data-independent acquisition mass spectrometry (DIA-MS), we developed a robust method to identify changes in histone modification recognition proteins during cancer progression. Our analysis revealed 22 proteins that were significantly upregulated and 22 proteins that were significantly downregulated in SW620 cells compared to SW480 cells. Notably, SMARCA1, a member of the ISWI family belonging to ATP-dependent chromatin remodeling complexes, was downregulated in SW620 cells compared to SW480 cells. Its high expression was strongly correlated with poor patient prognosis, aligning with the proposed role of SMARCA1 in promoting colorectal cancer (CRC) metastasis. Furthermore, reduced SMARCA1 expression altered the levels of metastasis-related matrix metalloproteinases (MMPs) in these cells. In conclusion, by systematically profiling histone modification recognition proteins in a matched pair of primary and metastatic CRC cell lines, we identified SMARCA1 as a potential driver of CRC metastasis and a promising therapeutic target for CRC patients.
... Consequently, the analysis exclusively scrutinizes the effects of either a single aromatic substance (lavender) or a combination of aromatic substances. The results reveal that the sole application of lavender proves more effective in enhancing sleep quality among older adults, aligning with the findings of Cheong et al. [26] Nevertheless, further research is imperative to ascertain whether the exclusive use of lavender surpasses other individual aromatics. In the realm of aromatherapeutic modalities, subgroup analyses indicate that non-inhalation aromatherapy potentially exerts a more favorable impact on improving sleep quality in older adults, consistent with the conclusions drawn by Her and Cho. ...
Article
Full-text available
Background Aromatherapy has been proposed as a complementary therapy to enhance sleep quality and regulate mood. However, few studies have specifically examined the efficacy of aromatherapy in managing sleep disorders in older adults. Therefore, the present study aims to systematically review the impact of aromatherapy on sleep quality among older adults. Methods It employed a meta-analysis design. A systematic and comprehensive search was conducted across 7 databases to identify randomized controlled trials examining the effects of aromatherapy on sleep quality in older adults. Two researchers independently assessed the quality of the literature. The study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analysis checklist. Results Aromatherapy demonstrated effectiveness in improving sleep quality among older adults (standardized mean difference [SMD] = −1.02; 95% confidence interval [CI] = −1.38 to −0.66; P < .001). Subgroup analyses based on aroma types, intervention modalities, and treatment durations revealed enhanced efficacy with lavender as the sole aroma (SMD = −1.39; 95% CI = −2.06 to −0.72; P < .001), non-inhaled aromatherapy (SMD = −1.73; 95% CI = −2.26 to −1.2; P < .001), and aromatherapy administered for less than 4 weeks (SMD = −1.16; 95% CI = −1.68 to −0.64; P < .001). Notably, significant effects of aromatherapy on anxiety (SMD = −0.83; 95% CI = −1.24 to −0.42; P < .001) and depression (SMD = −0.85; 95% CI = −1.30 to −0.39; P < .001) in older adults were also observed. Conclusion This study indicates that aromatherapy improves sleep quality in older adults, with single-use lavender, non-inhalation aromatherapy, lasting less than 4 weeks being particularly effective. Aromatherapy also alleviates depression, but its effects on anxiety require further evaluation.
... Methodological limitations are prominent, with many studies involving small sample sizes and short intervention durations that limit the applicability of the results beyond specific populations, such as nursing students or hospital patients (13) (20). Additionally, the lack of standardization in lavender administration-whether inhaled, applied topically, or used in varying dosages-complicates the comparison of results and the determination of optimal therapeutic methods (1) (11). ...
Article
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In today's fast-paced society, rising stress levels necessitate effective management strategies. While pharmacological treatments are common, their side effects have spurred interest in alternative therapies, particularly those rooted in natural remedies. Lavender (Lavandula angustifolia), long esteemed for its calming properties, has emerged as a promising non-pharmacological option. Historical use in herbal medicine for anxiety and stress-related disorders has inspired modern scientific research to explore its potential. This review synthesizes recent studies on lavender essential oil, examining its mechanisms—such as neurotransmitter modulation—and its effectiveness in diverse settings, from reducing stress among healthcare professionals to improving sleep quality. Despite promising results, limitations like small sample sizes and variability in application methods highlight the need for more rigorous research to establish lavender's efficacy and optimize its therapeutic use in stress management and mental health care.
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The revised edition of the Handbook offers the only guide on how to conduct, report and maintain a Cochrane Review. The second edition of The Cochrane Handbook for Systematic Reviews of Interventions contains essential guidance for preparing and maintaining Cochrane Reviews of the effects of health interventions. Designed to be an accessible resource, the Handbook will also be of interest to anyone undertaking systematic reviews of interventions outside Cochrane, and many of the principles and methods presented are appropriate for systematic reviews addressing research questions other than effects of interventions. This fully updated edition contains extensive new material on systematic review methods addressing a wide-range of topics including network meta-analysis, equity, complex interventions, narrative synthesis, and automation. Also new to this edition, integrated throughout the Handbook, is the set of standards Cochrane expects its reviews to meet. Written for review authors, editors, trainers and others with an interest in Cochrane Reviews, the second edition of The Cochrane Handbook for Systematic Reviews of Interventions continues to offer an invaluable resource for understanding the role of systematic reviews, critically appraising health research studies and conducting reviews.
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Background Commercially available baby vital monitors have been successfully marketed towards parents, specifically as an intervention to prevent Sudden Infant Death Syndrome (SIDS). The aim of this study was to determine if evidence suggests that commercially available sleep movement monitors should be routinely recommended by healthcare professionals. Methods A systematic literature review was undertaken to investigate the evidence for the efficacy of infant sleep monitors. The articles retrieved were then screened in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results Literature search yielded five relevant articles, a majority (80%) relating to SIDS. Two studies showed the monitor was effective in accurately detecting cessation of breathing but could not comment on their efficacy with regards to SIDS prevention. A study of 53 infants using the Babysense monitor after an Apparent Life-Threatening Event (ALTE) found the monitor accurately detected apnoea and bradycardia when compared to the cardiorespiratory monitor ‘Intellivue MP20 Junior’ by Phillips. Two qualitative studies reported that such devices were appealing to mothers. Discussion The medical effectiveness and reliability of these movement monitors is still a matter of controversy. Commercial monitors may be comparable to clinical cardiorespiratory monitors in terms of detection of apnoea and bradycardia. However, no article could conclude that sleep movement monitors are an effective method of SIDS prevention. Instead, healthcare professionals should emphasise interventions proven to reduce the risk of SIDS such as positioning infants on their back to sleep, or smoking cessation. Further limitations of the devices included a high rate of false alarms. Conclusion The systematic review revealed that there is no evidence that commercially available sleep movement monitors can prevent SIDS. Therefore, sleep movement monitors should not be routinely recommended by paediatricians. However, some of the studies have shown the potential for other uses for these monitors. There is some evidence to suggest that they may be of use for monitoring specific cohorts of infants, including those who have had a previous ALTE, or have cardiorespiratory risk factors. Further research into these areas is required.
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Background: Cognitive behavioural therapy for insomnia (CBTI) has been successfully applied to those with chronic illness. However, despite the high prevalence of post-stroke insomnia, the applicability of CBTI for this population has not been substantially researched or routinely used in clinical practice. Aims: The present study developed a 'CBTI+' protocol for those with post-stroke insomnia and tested its efficacy. The protocol also incorporated additional management strategies that considered the consequences of stroke. Method: A single-case experimental design was used with five community-dwelling individuals with post-stroke insomnia. Daily sleep diaries were collected over 11 weeks, including a 2-week baseline, 7-week intervention and 2-week follow-up. The Insomnia Severity Index, Dysfunctional Attitudes and Beliefs About Sleep Scale, Epworth Sleepiness Scale, Fatigue Severity Scale and Stroke Impact Scale were administered pre- and post-treatment, as well as at 2-week follow-up. Results: At post-treatment, three participants no longer met diagnostic criteria for insomnia and all participants showed improvements on two or more sleep parameters, including sleep duration and sleep onset latency. Three participants showed a reduction in daytime sleepiness, increased quality of life and reduction in unhelpful beliefs about sleep. Conclusions: This study provides initial evidence that CBTI+ is a feasible and acceptable intervention for post-stroke insomnia. Furthermore, it indicates that sleep difficulties in community-dwelling stroke populations are at least partly maintained by unhelpful beliefs and behaviours. The development and delivery of the CBTI+ protocol has important clinical implications for managing post-stroke insomnia and highlights directions for future research.
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Recent research suggests that sleep plays an important role in obesity (OB). No systematic reviews have investigated the association between OB and insomnia specifically. The present study reviewed the past 10 y of findings on the association between insomnia diagnosis (IND) and insomnia symptoms (INS) with OB. A total of 67 studies were included in the meta-analyses. Multilevel random effects models showed that the odds of having OB among those who had IND was not significantly greater than the odds of having OB among those who did not have IND (odds ratio (OR) = .80, p = .61). A small, significant cross-sectional correlation (r = .06, p = .03) was found between INS and body mass index. Longitudinal data were limited. Based on three studies, the odds of developing future INS among those who had OB were not significantly greater than those who were normal-weight (NW) (OR = 1.07, p = .40). Longitudinal data on the association between INS and future incidence of OB are inconclusive. We found no indication of systematic publication biases and high heterogeneity in the effect sizes across studies. Meta-regressions showed that some of the heterogeneity was explained by the types of measures of insomnia symptoms, publication year, and regions where a study was conducted.
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Introduction: This study identifies associations between sleep outcomes and sexual orientation net of sociodemographic and health-related characteristics, and produces estimates generalizable to the US adult population. Participants/methods: We used 2013-2015 National Health Interview Survey data (46,909 men; 56,080 women) to examine sleep duration and quality among straight, gay/lesbian, and bisexual US adults. Sleep duration was measured as meeting National Sleep Foundation age-specific recommendations for hours of sleep per day. Sleep quality was measured by 4 indicators: having trouble falling asleep, having trouble staying asleep, taking medication to help fall/stay asleep (all ≥4 times in the past week), and having woken up not feeling well rested (≥4 days in the past week). Results: In the adjusted models, there were no differences by sexual orientation in the likelihood of meeting National Sleep Foundation recommendations for sleep duration. For sleep quality, gay men were more likely to have trouble falling asleep, to use medication to help fall/stay asleep, and to wake up not feeling well rested relative to both straight and bisexual men. Gay/lesbian women were more likely to have trouble staying asleep and to use medication to help fall/stay asleep relative to straight women. Finally, bisexual women were more likely to have trouble falling and staying asleep relative to straight women. Conclusions: Sexual minority women and gay men report poorer sleep quality compared with their straight counterparts.