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Sauna and Mindfulness: How Sauna Bathing Affects
Psychological States and Traits Related to Bodily
Sensations and Emotions
Jimpei Hitsuwari
Helmut Schmidt University https://orcid.org/0000-0002-0061-5318
Takechika Hayashi
Kyoto University https://orcid.org/0009-0003-4092-745X
Woodman Katarina
Kyoto University https://orcid.org/0009-0003-9661-0865
Meiyi Du
Kyoto University
Misaki Morita
Kyoto University
Shota Takiguchi
Kyoto University
Yutaka Yamashita
Kyoto University
Michio Nomura
Kyoto University https://orcid.org/0000-0003-1043-2811
Research Article
Keywords: sauna, mindfulness, bodily sensation, aesthetic experience, emotion
Posted Date: September 2nd, 2024
DOI: https://doi.org/10.21203/rs.3.rs-4991388/v1
License: This work is licensed under a Creative Commons Attribution 4.0 International License.
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Additional Declarations: The authors declare no competing interests.
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Abstract
Despite its popularity, little psychological and cognitive science research has investigated sauna bathing,
especially among healthy individuals. This study empirically examines the connection between sauna
bathing and psychological factors related to bodily sensations and emotional experiences. Two
experiments were conducted with healthy subjects. In Study 1, we recruited 180 participants and
categorized them into three groups (regular sauna, irregular sauna, and no sauna conditions). The
participants were asked to complete an online questionnaire which asked about mindfulness and
positive emotions. Study 2 was a eld study conducted with 28 participants using a sauna at a spa
facility. Before and after bathing, the participants answered a questionnaire similar to that used in Study
1. Twelve participants who took sauna baths and 16 of the participants who did not take sauna baths
were included in the analysis. Study 1 showed that sauna bathers had a higher ability of bodily sensory
imagery and a higher aesthetic evaluation of haiku poetry. Study 2 showed that sauna bathing increased
the observing trait of mindfulness. Although the relationship between sauna bathing and bodily
sensations or emotional experiences has been mentioned by sauna users and books, this is the rst time
that it has been empirically demonstrated. These results are considered to be caused by the increased
sensitivity of bodily sensations and the heightened parasympathetic nervous system owing to the high
and low temperatures. However, more detailed mechanisms are expected to be elucidated in the future.
Introduction
In recent years, saunas have become increasingly popular in Japan and worldwide, with their market size
expected to continue to grow over the next ve years (Mordor Intelligence, 2024). Correspondingly,
sauna research has gained momentum, with the number of studies increasing from a few in the 1950s to
more than 50 annually in recent years (PubMed; Figure 1). A sauna session consists of a few minutes in
the sauna room at a high temperature, usually between 70°C and 100°C, followed by a cold bath or
shower and a rest session in a well-ventilated room. During sauna bathing, the high temperature raises
the body temperature, dilates the blood vessels, and activates the sympathetic nervous system
(Laukkanen, Lipponen, et al., 2019). In the cold bath, the sympathetic nervous system is reactivated at
the same time as the blood vessels constrict; however, the parasympathetic nervous system is
signicantly activated by the nal rest, leading to a state of so-called “deep relaxation” (Saunar no Hikaru,
2023) or “
totonou
” (Chang et al., 2023, 2024). “
Totonou
” means “to be organized” in Japanese, although
here, it refers to a state of happiness in which the sauna automatically conditions the body and mind and
restores natural capacities (Chang et al., 2023). The sauna environment and the associated changes in
the autonomic nervous system are likely to be related to consciousness, emotions, mindfulness, and
mental imagery. Two systematic reviews on saunas have recently been carried out (Hussain & Cohen,
2018; Nagae, 2022). However, in the former, only six out of the 40 studies (Hussain & Cohen, 2018), and
in the latter, none of the studies (Nagae, 2022) focused on healthy individuals. As most sauna studies
have been conducted with clinical groups, they have focused predominantly on treating illness or injury
and sauna bathing’s association with health, meaning few psychological studies on sauna bathing have
been undertaken (Chang et al., 2023).
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[Figure 1 near here]
A limited number of studies on healthy individuals have recently begun to be conducted, including global
surveys involving multiple ethnic groups (Hussain et al., 2019) and cohort studies (T. Laukkanen,J. A.
Laukkanen,et al., 2019). For example, Laukkanen,J. A. Laukkanen,et al. (2019) associated 203
psychiatric disorders that developed during 24.9 years (median) of follow-up with sauna habits and
showed that individuals who took sauna baths 4–7 times a week had a 77% lower risk of developing
psychosis than those who took a sauna bath once a week. Several studies have also used neuroscience
methods (Cernych et al., 2018; Chang et al., 2023). Chang et al. (2023) conducted an
electroencephalogram before and after sauna and showed that alpha power and theta power, which
suggest a state of relaxation, increased and that the amount of theta power increase positively
correlated with the subjective rating of pleasure. However, considering the popularity of and attention
paid to sauna bathing, and the fact that it is a dynamic experience involving the mind and body, there are
many remaining questions to be addressed. In this study, we focus on two gaps in the existing research
and attempt to extend the existing ndings.
First, and overlapping with the above, is the bias in the samples used, such as those comprising disease
groups. In addition, other studies have focused on men in their 80s (Strandberg et al., 2018) and
homosexual individuals (Lee et al., 2012). In studies with the general population, most participants either
did not use a sauna (Podstawski et al., 2015), or, conversely, even the least frequent sauna users went
once a week (Kunutsor et al., 2024; Laukkanen et al., 2017). For example, Hussain et al. (2019) showed a
positive effect of sauna bathing on mental health, but on the basis that the group that engaged in sauna
bathing 5–15 times a month scored higher than the group that did so fewer than ve times a month.
Comparisons with non-sauna users need to be made as this frequency of sauna use (even ve times a
month) is likely to be uncommon in the overall population, except in countries where saunas are part of
everyday life.
Second, most related studies have examined well-being, anxiety, or stress as dependent variables
(Hayasaka et al., 2008; Podstawski et al., 2015; Podstawski et al., 2024), which contrasts the potentially
wide range of benets of the sauna experience. In the following sections, aspects that have been
suggested to be associated with sauna bathing in terms of bodily sensations and emotional experiences
will be highlighted and linked to the aims of the present study.
Bodily Sensations
As is to be expected given that they involve placing oneself in a space of hot and cold temperatures,
sauna experiences have the potential to induce physical transformations. The rst thing to consider is
the relationship between sauna bathing and mindfulness. The relationship between saunas and
mindfulness or meditation has often been noted at the descriptive level, suggesting positive effects
(Harju, 2023; Jaglarz, 2013). Such discourses frequently refer to the experience of emptying one’s mind
and being able to focus on what is in front of oneself. The term “saunafulness” has even been developed
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by combining the concept and practice of mindfulness with the characteristics of sauna bathing (Harju,
2023). Meditation practitioners have also described mindfulness experiences in saunas (Amaro, 2010).
Amaro (2010) reported being able to stop thinking for the rst time inside the sauna room, and
additionally, that the slowing down of thoughts persisted even after leaving the sauna. Thus, sauna
bathing may increase the tendency toward mindfulness.
Second, saunas could be related to the ability to vividly evoke imagery, including bodily sensations.
Mental imagery has long been examined in psychology, with increasing attention being paid not only to
visual imagery but also to mental imagery for each sensory system, including auditory, tactile, and bodily
sensations (Andrade et al., 2014; Hitsuwari et al., 2023). It is possible that a quiet place or relaxing
environment may increase the clarity of mental imagery while also being associated with a state of
mindfulness. Preliminary results showed that a sauna bathing group scored higher than a control group
on the item “I could see images from my memory or imagination with extreme clarity” (Chang et al.,
2023).
Emotional Experience
Although saunas are often used for reasons of pleasure and comfort, further clarication is needed as to
which emotional experiences and tendencies of positive emotions are associated with sauna use. While
sauna bathing may be associated with positive emotions, such as improved well-being (Hussain et al.,
2019) and reduced anxiety (Hayasaka et al., 2008), it is important to capture the related emotions in
greater breadth and detail.
Shiota et al. (2006) attempted to distinguish seven positive emotions that are not global positive
emotions as measured by the Positive and Negative Affect Schedule (Watson et al., 1988): joy,
contentment, pride, love, compassion, amusement, and awe. The differential associations of these
emotions with the Big Five and attachment styles suggest that they are distinct emotional tendencies
(Shiota et al., 2006). These positive emotions include what are called self-transcendent emotions, such
as awe and gratitude (Stellar et al., 2017). One denition is: “Under certain circumstances, the subjective
sense of one’s self as an isolated entity can temporarily fade into an experience of unity with other
people or one’s surroundings, involving the dissolution of boundaries between the sense of self and
‘other’” (Yaden et al., 2017, p. 143). Such self-transcendent emotions and sensations are also thought to
be related to the sauna experience; for example, according to Tokyo Sauna Japan (2023), sauna lovers
describe that the relaxed state after a sauna “feels connected to the universe” or “feels like becoming
one with that place and merging into a single entity.” In other words, sauna bathing may evoke self-
transcendent emotions. This is consistent with the idea that mindfulness leads to self-transcendence
(Hanley et al., 2023) and that saunas are sacred and sometimes religious spaces with a deep connection
to purication (Leipämaa-Leskinen et al., 2020; Wolff et al., 2024).
In association with self-transcendent emotions such as awe, sauna bathing may also inuence aesthetic
emotional experiences. Indeed, teamLab, a Japanese artist group, opened a popular temporary facility
where visitors could view artworks after sauna bathing, which became popular (Furutani, 2021).
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Describing the exhibition, TeamLab (2021) noted, “Visitors immerse in the art after the sauna, when their
senses are sharpened, their minds are clear and they are in a state of ‘perfect concentration,’ where
beautiful things seem even more beautiful. They get an experience that they do not realize with their
normal senses.”
Aim
This research examines the relationship of sauna bathing habits (Study 1) and actual sauna bathing
(Study 2) with psychological tendencies related to bodily sensations and emotional experiences. In
addition to measures of well-being and anxiety tendency, which have been shown to be related to sauna
bathing in previous studies, we used measures related to bodily sensations, such as mindfulness and
multisensory mental imagery ability, and more precise measures of emotions, such as positive and self-
transcendent emotion. Sauna bathing was expected to show positive correlations with these scales. We
also considered socioeconomic status (SES) and health orientation, which have been associated with
sauna bathing in previous studies, as control variables. Regarding SES, sauna bathing frequency is
positively related to higher education (Hussain et al., 2019), place of permanent residence, parents’
education level, and students’ monthly budget (Podstawski et al., 2015). Regarding health orientation,
many people use saunas for health purposes, and more than 80% of all respondents cite “to improve
circulation,” “detoxication,” and “to improve sleep” as motivations for sauna bathing (Hussain et al.,
2019). In other words, to exclude the explanation that only people with high SES and health orientation
obtain positive psychological effects from sauna bathing, these factors were controlled for in the
analysis. The study was approved by the Ethical Review Committee of the Graduate School of Kyoto
University (CPE-584), and all procedures were carried out in accordance with their requirements and the
Declaration of Helsinki. All anonymized data and R-scripts for analysis from Studies 1 and 2 are openly
available for reference (https://osf.io/8ysmr/?view_only=25732ebcf3b14c83927183071016d596).
Study 1
Method
Participants
We recruited 60 people with a sauna habit (attending sauna at least once a week; regular sauna
condition), 60 with almost no sauna habits (not attending sauna but had the opportunity to attend in the
last 6 months; irregular sauna condition), and 60 with no sauna habit at all (had no opportunity to go to
saunas in the last 6 months; no sauna condition). The sample size was calculated assuming analysis of
covariance (ANCOVA) as the main analysis method (moderate effect size f = .25, power = .80,
signicance level = .05), with the three conditions among these participants as independent variables
and measures such as well-being as dependent variables, controlling for SES and health orientation.
Calculations using G*Power (3.1.9.7; Faul et al., 2009) yielded a total required sample size of 158
participants. Considering that a 10% missingness rate is possible in an online survey (Hoerger, 2010),
180 participants (60 per condition) were included in the study. After excluding participants who failed the
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attention check, 57 had a regular sauna habit (Mage = 41.72, SDage = 9.35, 36 men, 21 women), 60 had an
irregular sauna habit (Mage = 41.92, SDage = 8.89, 29 men, 31 women), and 60 had no sauna habit (Mage =
41.40, SDage = 8.98, 31 men, 29 women).
Materials
Twelvescales were utilized for measurements. The rst three variables measured were more general
variables, as examined in previous studies; variables four and ve were related to bodily sensation;
variables six to 10 were related to higher-order emotional experiences, including self-transcendent
emotion and spirituality; and variables 11 and 12 were controls.
Satisfaction with Life Scale. The Satisfaction with Life Scale (SWLS;Diener et al., 1985) is a ve-item
instrument that is answered using a7-point Likert scale and includes items such as “In most ways, my
life is close to my ideal.” We used the Japanese version of this scale (Sumino, 1994) as an indicator of
well-being.
State-Trait Anxiety Inventory. We used only the characteristic scales of the Japanese version of the
State-Trait Anxiety Inventory (STAI;Nakazato & Mizuguchi, 1982; Spielberger et al., 1971). The
participants rated 20 items, such as “I feel good,” on a 4-point scale from “1 = Almost never” to “4 =
Often.”
Ten-Item Personality Inventory. We used the Japanese version of thisBig Five A scale, which consists of
10 items on ve subscales that measure personality (Gosling et al., 2003; Oshio et al., 2012). For
example, extraversion is rated using a 7-point scale ranging from “1 = I think not at all” to “7 = I strongly
agree.”
Five Facet Mindfulness Questionnaire, Short Version. The Japanese version of the Five Facet
Mindfulness Questionnaire, short version (FFMQ;Baer et al., 2006; Takahashi et al., 2022) comprises 24
items that measure trait mindfulness acrossve subscales (nonreactivity, observing,
actingwithawareness, describing, and nonjudging). For example, observation, measured using items like
“I pay attention to sensations such as the wind in my hair or the sun on my face,” is rated on a 5-point
scalefrom “1 = Never or very rarely true” to “5 = Very often or always true.”
Plymouth Sensory Imagery Questionnaire, Short Version. The Plymouth Sensory Imagery Questionnaire
(short version) (Psi-Q; Andrade et al., 2014) utilizesseven subscales to measure multisensory mental
imagery ability. The Japanese version, used in this study (Hitsuwari & Nomura, 2023), does not include
“emotional feeling” and has 21 items across six subscales:vision, sound, smell, taste, touch, and bodily
sensation. For example, for vision, items such as “Imagine the sound of …” followed by the word “bonre”
are rated using a 7-point scale ranging from “1 = No image at all” to “7 = As vivid as real life.”
Dispositional Positive Emotion Scale. We used the Japanese version of the Dispositional Positive
Emotion Scale (DPES;Shiota et al., 2006; Sugawara et al., 2020),a 38-item instrument that measures the
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tendency to feel positive emotions across seven subscales (joy, contentment, pride, love, compassion,
amusement, and awe). For example, for joy, respondents answer the item “I often feel bursts of joy” on a
7-point scale ranging from “1 = I totally disagree” to “7 = I strongly agree.”
Gratitude Questionnaire-Six Item Form. The Gratitude Questionnaire-Six Item Form (McCullough et al.,
2002) isa six-item scale measuring gratitude propensity. The Japanese version, used in this study
(Shiraki & Igarashi, 2014), contains ve items because one item was dropped during the reliability and
validity validation stages. For example, items such as “I have so much in life to be thankful for” are
answered on a 7-point scale ranging from “1 = Strongly disagree” to “7 = Strongly agree.”
Aesthetic Evaluation ofArt (HaikuPoetry). The haiku, the world’s shortest poem, was used to measure
the aesthetic perception of art. A haiku can be appreciated in a short time, and evaluation tasks can be
easily carried out on a computer (Hitsuwari & Nomura, 2022).Haikus are associated with self-
transcendent emotions (Kato & Hitsuwari, 2024).Five haikus were evaluated using a 7-point scale
ranging from “1 = Not beautiful at all” to “7 = Very beautiful.”
Japanese Youth Spirituality Rating Scale. The Japanese Youth Spirituality Rating Scale (Nigorikawa et al.,
2016) usesve subscales to measure Japanese spirituality (harmonizing with nature,
Ikigai
[the
Japanese word for one’s sense of purpose in life], awe toward the invisible, connecting with one’s
ancestors, and self-determination) on a 27-item scale. For example, for items such as “harmonizing with
nature,” the scale includes statements like “Being in nature gives me energy” and “I feel that I have a lot
of energy.” Items are rated on a 7-point scale ranging from “1 = Not at all true” to “7 = Very true.”
Time Perception.A four-item scale measuring time perception was used (Rudd et al., 2012). Items such
as “I have lots of time in which I can get things done” were answered using a 7-point scale ranging from
“1 = Strongly disagree” to “7 = Strongly agree.” The higher the score, the more time the participant
perceived that they had available.
Socioeconomic Status. Several questions were used to measure SES (Shimizu et al., 2021; Yanagisawa
et al., 2013). First, participants reported their approximate annual household income using a 12-point
system, ranging from “less than 12 million yen” to “more than 12 million yen”(SES income). Second, the
participants answered the question, “If the whole of current Japanese society were to be divided into ve
strata, where would you place your household income?”, using a ve-factor system: “high,” “above
middle,” “below middle,” “above low,” and “below low”(SES ranking).Third, participants answered three
questions regarding their subjective currentand childhoodSES. For example, for subjective childhood
SES, the item “My family usually had enough money for things when I was growing up” was rated using a
7-pointscaleranging from “1 = Strongly disagree” to “7 = Strongly agree.”
Health Orientation.We useda 10-item scale measuring health awareness and health-related behavioral
practices (Takahashi & Muto, 1992). An example item is, “Do you think you are a person who takes care
of your health?” The other items were answered using a 4-point scale ranging from “1 = Not at all true” to
“4 = Very true.”
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Procedure
Participants were recruited using CrowdWorks (https://crowdworks.jp/), a Japanese online
crowdsourcing company, and completed a questionnaire created on Qualtrics
(https://www.qualtrics.com/). After signing an informed consent form, they answered the
abovementioned questionnaire and questions related to sauna use (e.g., frequency of sauna attendance,
sauna history, motivation, sauna bathing methods, psychological and physical effects), their haiku and
art experiences and interests, and their demographic information.
Results and Discussion
Descriptive statistics for the three conditions and the results of the one-factor analysis of variance
between participants are presented in Table 1.The analysis of variance (ANOVA) was conducted using
the
anovakun
package (ver. 4.8.6.; Iseki, 2021) in R (ver. 4.2.3; R Core Team, 2023), and multiple
comparisons were conducted using the Shaffer method.
[Table 1 near here]
The results in Table 1 show that there were signicant differences in the three-group comparisons in the
Psi-Q’s somatosensory imagery ability (
F
(2, 174) = 3.38,
p
= .04,
η2
= .04), evaluations of the beauty of
the haikus (
F
(2, 174) = 3.88,
p
= .02,
η2
= .04), and subjective current SES (
F
(2, 174) = 3.87,
p
= .02,
η2
=
.04). Next, we conducted an ANCOVA, controlling for SES and health orientation. Several measures of
SES were employed in this research; however, in the ANCOVA, we used the participants’ subjective
current SES, which was signicantly different in the ANOVA.Using the
lmres
function within the R
pequod
package (Mirisola & Seta, 2016), bodily sensory imagery ability and theaestheticevaluation of
the haikus were entered as dependent variables, the experimental condition of sauna bathing frequency
was entered as the independent variable, and SES and health orientation were entered as control
variables. The effects of bodily sensationimagery ability(a subscale of the Psi-Q; Figure 2a)andthe
aestheticevaluationof haiku poetry (Figure 2b)remained signicant in an ANCOVA that controlled for
health orientation and subjective SES(Supplemental Material, Table S1).
[Figure 2 near here]
The irregular sauna and no sauna conditions were grouped together and compared post hoc according
to regular sauna attendance. Thet-testsshowed a signicant effect of the sauna condition on the
aesthetic evaluation of haiku poetry and subjective current SES. The t-test also showedsignicant trends
ofthe sauna conditionin nonreactivity,Psi-Q, taste imagery ability,
contentment,pride,amusement,awe,harmonizing withnature, and
Ikigai
(Figure 3; see also
Supplemental Material, Table S2 for statistical values).The aesthetic evaluation of haikus remained
signicant when controlling for subjective current SES and health orientation (
b
= -.31,
SE
= .13,
t
= -2.42,
β
= -.18,
p
= .02), whereas other variables were not signicant.
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[Figure 3 near here]
The results of Study 1 showed an association between the frequency of sauna bathing and some
psychological variables, particularly bodily sensation imagery ability and the aesthetic evaluation of
haikus. These variables have been suggested to be related at the observational level; however, using
statistical analysis, this study empirically revealed an association for the rst time. With its repetition of
hot and cold exposure, sauna can draw attention to the body and cause its imagery to become clearer,
even if an individual is not in the sauna room. The association with the aesthetic evaluation of haikus
was also consistent with the aim of the above-mentioned exhibition (teamLab, 2021), which sought to
enhance the art experience by clearing the mind in the sauna. However, Study 1 did not reveal causal
relationships, such as whether sauna bathing (a habit) affected these physical, emotional, and
psychological tendencies, or whether individuals with a higher propensity toward such tendencies were
more likely to take sauna baths. In Study 2, we examined the psychological effects of sauna bathing
through a eld experiment at a bathing facility with saunas.
Study 2
Method
Participants
A eld study was conducted at the
Sagano Onsen Tenzan no Yu
(https://www.ndg.jp/tenzan/), a bathing
facility in Kyoto, Japan. The main analysis was a one-sample t-test, with the pre–post scale used as the
dependent variable. A medium effect size (d = 0.5) was assumed using G*Power (3.1.9.7; Faul et al.,
2009) with a power of .80 and a signicance level of .05 (N = 27). Excluding those who did not take a
sauna bath or dropped out, 35 participants were recruited: Three did not respond post, and four did not
state whether they had taken a sauna bath or not, leaving 28 participants for analysis. Furthermore, more
participants than expected did not take sauna baths: 12 took sauna baths (Mage = 53.42, SDage = 15.79, 7
men, 4 women, and 1 who did not disclose their gender) and 16 did not (Mage = 50.25, SDage = 18.77, 5
men, 11 women).
Materials and Procedures
Facility users were approached at the entrance and asked to complete a questionnaire similar to that
used in Study 1 before and after bathing. The questionnaire consisted of questions on the SWLS, time
perception, the Self-Transcendence Scale (see below), the Observingsubscale ofthe FFMQ, the DPES,
the Psi-Q, theaestheticevaluation of ve haikus, health orientation, SES, sauna bathing, and
demographic information. The Self-Transcendence Scale (Castelo et al., 2021)consisted of four items,
including “I feel that on a higher level, all of us share a common bond,” which were answered using a 7-
point scale ranging from “1 = Strongly disagree” to “7 = Strongly agree.”
Results and Discussion
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The pre–post descriptive statistics for the 12 participants who did and 16 who did not take a sauna bath
are presented in Table2.
[Table 2 near here]
First, a pre–post one-sample t-test was conducted on all measures for which data were collected for the
12 participants who took sauna baths. The results showed that none of the variables were signicantly
different. Next, a post-hoc comparison was made between the participants who took sauna baths and
those who did not. Multiple regression analysis was conducted with post-scores as the dependent
variable; the presence or absence of sauna bathing as the independent variable; and pre-scores, health
orientation, andsubjective current SESas control variables. The results showed that only observing (
b
=
-.53,
SE
= .23,
t
= -2.30,β =-.34,
p
= .03) was affected by having a sauna bath (Figure4).
[Figure 4 near here]
The results of Study 2 showed that the scores for observing, a subscale of mindfulness, increased after
sauna bathing. This is consistent with the observation that sauna use increases mindfulness (Harju,
2023). Sauna bathing elevates attention to external events and internal experiences such as sensations,
feelings, and thoughts through bodily sensations. It should also be noted that the insucient sample
size of this study is a limitation, and future experiments with larger samples in a more controlled
environment are required.
General Discussion
This research examined how sauna bathing frequency (Study 1) and actual sauna bathing (Study 2) are
associated with psychological factors related to bodily sensory and emotional experiences. In Study 1,
bodily sensory imagery ability and the aesthetic evaluation of haikus were associated with frequency of
sauna use. In Study 2, observing (part of mindfulness) was positively associated with sauna bathing,
even after controlling for SES and health orientation. Though there has been an increase in the number of
studies on sauna bathing, in line with its growing popularity in real-life situations, the majority of the
research has focused on individuals with diseases (Hussain & Cohen, 2018; Nagae, 2022). We provide a
new perspective on sauna research by investigating healthy individuals and those who use saunas in
real-life situations, rather than in therapeutic settings. In particular, we were able to measure several
variables related to bodily sensations and emotional experiences, beyond those that have been
examined several times in previous studies, such as well-being and anxiety tendencies (Hayasaka et al.,
2008; Hussain et al., 2019; Podstawski et al., 2015).
First, as expected, sauna bathing improved bodily sensory imagery ability and mindfulness. The
environment of being exposed to high and low temperatures may have sharpened bodily sensations and,
at the same time, cleared the mind, leading to a state of mind that is not overconcentrated but rather
observing the inside and outside of the body. These changes may persist even after leaving the sauna
room, coinciding with what Amaro (2010) described in his recordings of meditation experiences in
Page 11/24
saunas. Studies examining the relationship between sauna bathing and heart rate variability suggest that
the sympathetic nervous system is heightened during sauna bathing, whereas the parasympathetic
nervous system becomes dominant during cooldown (Laukkanen, Lipponen, et al., 2019). Similarly, heart
rate variability is known to increase after mindfulness meditation practice (Azam et al., 2016), and it is
possible that sauna and mindfulness have similarities in terms of autonomic nervous system activity.
Regarding emotional experiences, the results suggest that sauna bathing may enhance aesthetic
experiences and emotions. One artist group’s (teamLab, 2021) assumption that a rich art experience
could be gained after sauna is likely to be correct. Given that the above-mentioned observing factor of
mindfulness is known to be associated with both affective and cognitive empathy (Himichi et al., 2021),
the increased sensitivity of haiku appreciation with sauna experiences can be coherently accounted for
by mindfulness and empathy. Neuroscientic evidence suggests that pleasant aesthetic experiences are
associated with default mode networks (DMN; Bel et al., 2019). To date, there have been several sauna
neuroscience studies (Cernych et al., 2018; Chang et al., 2023) but no magnetic resonance imaging
studies. As such, the relationship between sauna bathing and DMN remains unclear, but it is quite
possible that the relaxed state after sauna may enhance DMN. Though these are all important new
ndings, it is interesting that Study 1 and Study 2 produced different results. This suggests that a sauna
bathing habit (Study 1) and one-time sauna bathing (Study 2) may cause different psychological effects.
In other words, a single experience of sauna bathing may lead to a state of mindfulness, resulting in
sharpened bodily sensory imagery and enhanced aesthetic sensitivity as sauna bathing becomes a
habit. This difference can be an important topic for future research.
Some limitations should also be mentioned. First, the method of sauna bathing was not strictly
controlled. Sauna bathing is often combined with cold water and open-air bathing to reach relaxation, but
some may not engage in sauna bathing in this way. The time spent in the sauna and the temperature
also varied. Some previous studies have been conducted in controlled experimental settings (Chang et
al., 2023; Podstawski et al., 2024), and it is suggested that this psychological experiment should be
conducted in a similar way. Second, although we demonstrated a positive association between sauna
bathing habits and the aesthetic evaluation of haikus, it is challenging to generalize this association to
other art genres. As in teamLab’s (2021) attempt, immersive art experiences after sauna bathing may
generate additional aesthetic experiences, and there may be other forms in which such associations are
less likely to be found.
Conclusion
We examined the association between sauna bathing and psychological factors related to bodily
sensations and emotional experiences, nding positive relationships with bodily sensory imagery, the
aesthetic evaluation of haikus, and the observing tendency. It is expected that these results will be a
catalyst for increasingly active sauna research in the elds of psychology and cognitive science. The
results could also generate positive effects for the thriving sauna market and may provide insights into
how even healthy people can further enrich their lives through sauna use.
Page 12/24
Declarations
This work was supported by a Grant-in-aid for Scientic Research and JSPS KAKENHI (Grant number:
22H01103) and the 59th Incube Prize (Leave a Nest Co.). The authors thank the
Sagano Onsen Tenzan
no Yu
for allowing us to carry out Study 2. We also thank Editage (https://app.editage.jp/) for the English
proofreading.
All anonymized data and R-scripts for analysis from Studies 1 and 2 are openly available for reference
(https://osf.io/8ysmr/?view_only=25732ebcf3b14c83927183071016d596).
Correspondence concerning this article should be addressed to Michio Nomura, Kyoto University,
Yoshida Honmachi, Sakyo-ku, Kyoto, 606-8501, Japan. Email: nomura.michio.8u@kyoto-u.ac.jp.
Telephone: +81 075-753-3004.
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Tables
Table 1
Descriptive Statistics and Results of Analysis of Variance for Study 1
Page 18/24
Regular-sauna
(RS) Irregular-sauna
(IS) No-sauna
(NS) ANOVA
mean SD mean SD mean SD Multiple
Comparison
SWLS 3.54 1.47 3.34 1.60 3.16 1.43
STAI 2.28 .55 2.47 .67 2.39 .53
Big Five
Extraversion 3.61 1.50 3.64 1.42 3.22 1.48
Agreeable 5.16 1.10 5.03 1.18 5.14 1.25
Conscientious 4.35 1.39 4.04 1.42 3.90 1.78
Neuroticism 3.85 1.46 4.03 1.54 3.98 1.66
Openness 3.75 1.39 3.58 1.35 3.62 1.41
FFMQ 3.28 .45 3.22 .44 3.22 .47
Observing 3.20 .69 3.31 .80 3.42 .59
Describing 3.09 .78 2.99 .82 2.97 .91
Acting with
awareness 3.84 .79 3.79 .66 3.78 .71
Nonjudging 3.18 .71 3.11 .61 3.05 .66
Nonreacting 3.07 .63 2.89 .73 2.90 .67
Psi-Q 5.52 .80 5.28 .75 5.27 .72
Vision 5.82 .80 5.54 .93 5.74 .76
Sound 5.99 .82 5.84 .82 5.74 .89
Smell 4.53 1.36 4.22 1.15 4.27 1.15
Taste 5.50 1.04 5.18 1.11 5.24 1.01
Touch 5.73 1.07 5.54 .92 5.53 .92
Bodily sensation 5.54 .91 5.38 .88 5.12 .86 RS > NS
DPES
Joy 4.10 1.11 3.75 1.35 3.88 1.16
Contentment 4.07 1.35 3.70 1.53 3.69 1.42
Pride 4.01 1.13 3.59 1.27 3.78 1.13
Page 19/24
Love 4.06 1.19 3.58 1.37 3.88 1.22
Compassion 4.65 1.04 4.42 1.10 4.57 .99
Amusement 3.82 1.13 3.45 1.02 3.54 1.20
Awe 4.05 1.03 3.68 1.10 3.78 1.04
Gratitude 5.12 1.16 4.93 1.35 5.24 1.06
Aesthetic evaluation of
haikus 4.92 .82 4.61 .76 4.54 .77 RS > IS, RS > NS
Spirituality 4.33 .85 4.19 1.01 4.27 .87
Harmonizing with
nature 5.36 1.06 4.90 1.35 5.15 1.15
Ikigai 4.23 1.40 3.77 1.59 3.81 1.51
Awe towards the
invisible 4.20 1.22 4.19 1.32 4.22 1.13
Ancestors 3.79 1.35 3.82 1.42 3.70 1.46
Self-determination 4.05 1.37 4.29 1.26 4.47 1.37
Time perception 3.07 1.08 2.70 .81 2.97 1.04
SES
Income 4.61 2.10 5.17 2.53 4.57 2.47
Ranking 2.61 .56 2.57 .62 2.40 .72
Subjective current
SES 2.23 .52 2.10 .66 1.93 .56 RS > NS
Subjective
childhood SES 2.57 .62 2.56 .56 2.54 .73
Health orientation 2.98 .50 2.89 .50 2.96 .47
Note.
Multiple comparison shows only variables for which multiple comparisons in ANOVA resulted in an
adjusted
p
< 0.05.
Table2
Descriptive Statisticsfor Sauna Condition and Pre–post Condition
Page 20/24
Sauna No sauna
Pre Post Pre Post
Mean SD Mean SD Mean SD Mean SD
SWLS 4.37 1.35 4.10 1.59 4.05 1.47 4.35 1.34
Observing (FFMQ) 3.33 .56 3.79 .77 3.84 .85 3.86 .91
Psi-Q 5.28 .74 5.20 .95 5.58 1.37 5.65 1.26
Vision 5.61 .58 5.47 .95 5.85 1.38 5.88 1.29
Audio 5.42 1.05 5.36 1.11 5.92 1.29 5.85 1.40
Smell 4.58 1.17 4.58 1.33 5.27 1.56 5.46 1.75
Taste 5.44 1.17 5.36 1.26 5.52 1.52 5.54 1.39
Touch 5.25 1.06 5.36 1.17 5.62 1.60 5.75 1.26
Bodily sensation 5.39 .91 5.06 1.23 5.31 1.63 5.44 1.62
DPES
Joy 4.49 1.43 4.47 1.33 4.61 1.24 4.89 .91
Contentment 4.68 1.38 4.72 1.49 4.62 1.39 4.76 1.11
Pride 4.03 1.33 4.05 1.35 3.99 .98 4.42 .84
Love 4.50 1.03 4.33 1.35 3.81 1.25 4.17 .96
Compassion 5.23 .95 5.25 .91 4.96 .90 5.04 1.31
Amusement 4.65 .96 4.70 1.12 4.40 1.09 4.65 .72
Awe 4.62 .83 4.71 1.23 4.62 1.28 5.01 .95
Aesthetic evaluation of haikus 4.47 .90 4.02 1.10 4.11 1.31 4.06 1.00
Time perception 3.10 1.07 3.29 1.27 3.33 .98 2.95 1.06
Self-transcendence 3.85 1.29 4.12 1.03 4.27 1.11 4.23 1.64
SES
Income - - 4.42 3.03 - - 3.94 2.32
Ranking - - 2.58 1.24 - - 2.75 .58
Subjective current SES - - 10.25 2.22 - - 9.56 2.06
Subjective childhood SES - - 8.83 4.09 - - 8.75 2.52
Health orientation 2.87 .71 - - 3.19 .51 - -
Page 22/24
Figure 2
Plots of bodily sensationimagery ability subscale of Psi-Q (a) and aesthetic evaluation of haiku poetry (b)
for the three groups
Note.
RS = Regular-sauna condition, IS = Irregular-sauna condition, NS = No-sauna condition.
Page 23/24
Figure 3
Radar plots for comparison between the regular sauna condition and non-sauna condition regarding
general variables (a), bodily sensation variables (b), and emotional experience variables (c)
Note.
Several instruments were adjusted to a 7-point scale in order to display them on the same radar
chart. Current SES = Subjective current SES, Child SES = Subjective childhood SES, HwN = Harmonizing