Why do People Relax
when they Go to the Forest?

M

any of us know from experience thatgoing to the forest is relaxing. However,few people know why. One person who
does is Miyazaki Yoshifumi, Emeritus Professor
at Chiba University and Doctor ofMedicine. He is a world-renowned
authority on forest medicine andan advocate of forest therapy,
which is defined as forest bathing
supported by scientific evidence.
We asked him about the relaxing
and preventative medical effects offorest bathing.

ing) was coined in 1982 by Akiyama Tomohide, thenDirector General of the Forestry Agency. His goal wasto enhance the value of Japan’s forests by encouraging more people to visit them for relaxation. Then, in
1988, at the age of 34, I started myresearch on forest bathing to try tosolve a question that had fascinatedme since childhood: why do people
relax when they come into contact
with nature?

What kind of experiments haveyou done in your research on forest
Miyazaki Yoshifumi, Emeritus
bathing?
Professor at the Nature Therapy
Our research team conducted variCould you explain what forest
Lab, Center for Environment,
Health and Field Sciences, Chibaous experiments to find out how
bathing is?
University, and Doctor of Medicine
people’s stress levels change in forForest bathing is the practice of going(left), with Associate Professor Ikei
est and urban environments, andto the forest, synchronizing with it,
Harumi, who works with him on
forest bathing researchscientifically explained the relaxing
and experiencing comfort. People
effects of forests.
feel comfortable in a certain enviIn 1990, we conducted an experiment onronment when their own rhythm is in sync with it.
Yakushima Island that became the world’s first physiPeople experience a sense of comfort in the forest
ological experiment on forest bathing. In it, we anabecause of the long history human beings have withlyzed the concentration of cortisol, a type of stressnature. Humans emerged six to seven million years
hormone, in saliva using the latest technology availago, but most people have lived in urban environable at the time.
ments only in the 200 to 300 years since the Industrial
In addition, as part of the Forest Therapy Base
Revolution, a period that represents less than 0.01% of
Scheme launched in 2005, we conducted experiments
human evolution. In other words, humans have spentin cooperation with local governments and companies
more than 99.99% of their evolution in the naturalthroughout Japan, with the participation of 756 subenvironment. Since our genetic makeup does notjects at 63 forest and urban sites across the country.
change in the short period of several hundred years,
The purpose of the Forest Therapy Base Scheme was to
we are physically adapted to life in the natural enviaccumulate scientific evidence on forest bathing andronment. In contemporary society, however, we live into help revitalize local communities by enhancing thea state of constant hyper-vigilance, stress, and suscepvalue of forests. Our team was responsible for a largetibility to disease.
scale experimental project designed to accumulate
So, because we humans evolved in the naturalevidence. We conducted field experiments in forest
environment and are built to interact with and adapt
and urban environments, spending four to six days
to nature, we feel relaxed when we are in contact withand involving about 50 people at each site, including
it. This theory of mine has been named the “backresearch team members, subjects, and local governto-nature” theory by New Zealand researchers M. A.
ment staff. We also conducted indoor experiments
O’Grady and L. Meinecke.
on the physiological effects of visual, olfactory andIncidentally, the term “shinrin-yoku” (forest bath-6

HIGHLIGHTING JAPAN MAY 2024

JAPAN’S HEALING FORESTS < PART 1 >auditory factors. The scale of this project,which involved experiments at 63 sites,
was unprecedented globally, and I believe ithelped Japan become a world leader in forest bathing research.
What kind of evidence did you obtain inthese experiments?
In 2003, I proposed the concept of forest therapy, which means forest bathingbacked by scientific evidence. Through theexperiments carried out as part of the Forest Therapy Base Scheme through 2018,
we identified the following changes that
occur in the human body in a forest environment, and were able to determine thatspending time in the forest has a relaxing
effect.
A decrease in sympathetic nervous
activity (which is known to increaseduring times of stress)
A n increase in parasympathetic
nervous activity (which is known toincrease during relaxation)
A decrease in pulse rate
A decrease in blood pressureA decease in the concentration of thestress hormone cortisol (Fig. 1)
Calming of prefrontal cortex activity

Figure 1

Walking in the forest reduces stress and lowers theconcentration of stress hormones.

Mean of 348 males in their 20s (34 sites), forest vs. urban environments: statisticallysignificant difference
Modified from original data in H. Kobayashi, Y. Miyazaki et al., International Journal ofEnvironmental Research and Public Health 14:931, 2017

Figure 2

Physiological adjustment effect of forest therapy(diastolic blood pressure)We also conducted forest therapy program
experiments in the Akasawa Natural Recreation Forest, Nagano Prefecture, and Chizu
Town, Tottori Prefecture. The programs
included activities such as strolling in theforest, meditation, deep breathing, blindwalking, and “throwing” stress and anxi92 males in their 20s, forest walking: statistically significant negative correlation
Modified from original data in C. Song, Y. Miyazaki et al. International Journal ofeties at waterfalls to wash them away. The
Environmental Research and Public Health 12:4247-4255 2015
experiments produced some interesting
data. We found that these activities had asustained effect on lowering blood pressure in people
physiological functions. An experiment in which 92
with hypertension. The results showed that blood
subjects took a 15-minute walk in a forest resulted
pressure not only decreased after forest therapy, but
not only in a decrease in blood pressure in subjects
also remained at normal levels three to five days afterwith hypertension, but also in an increase in blood
the subjects returned to work.
pressure in subjects with hypotension (Fig. 2). SimiWe also found that forest bathing helps regulate
lar effects were not observed when the same subjects

Vol.192 HIGHLIGHTING JAPAN7

walked for 15 minutes in an urban environment. We called the effect of forest bathing
in bringing blood pressure to normal levels
a “physiological adjustment effect.”
Our research team provided scientificevidence to show that while forest therapy cannot cure diseases, it can be used tomake the body more resistant to disease.
This preventative medical effect of foresttherapy is expected to contribute to thereduction of medical costs (Fig. 3).

Figure 3

The concept of forest therapy

Photo: Agematsu Town Tourism Association

As a doctor of medicine, why do you study
both nature and people?
Forest therapy focuses on studying theModified from original data in Y. Miyazaki. Shinrin-yoku: The Japanese Way of Forest
effects of nature on people, but there is
Bathing for Health and Relaxation; Hachette UK Company, Octopus Publishing Group:
no system in Japan, Europe or the UnitedLondon, 2018
States that studies and provides education
with regard to both nature and people. I did not set outof Medicine, Tokyo Medical and Dental University, I
to become a human and forest researcher. However, aswas able to build a network in the fields of agriculturala result of my experience as a student at the Facultyscience and medicine, or in other words, nature andof Agriculture, Tokyo University of Agriculture andhuman research. In the past, the director of the CenTechnology, and my work as an assistant at the Faculty
ter for Health and Global Environment at the Harvard

People enjoying forest bathing at the Akasawa Natural Recreation Forest in Nagano Prefecture8HIGHLIGHTING JAPAN MAY 2024

Photo: Nonno-no-mori Nature Center

JAPAN’S HEALING FORESTS < PART 1 >Guided tour of Lake Kussharo and space in Tsubetsu Pass, Tsubetsu Town

School of Public Health in the United States and thedirector of the Finnish Forest Research Institute haveasked me for advice on how to implement research in
an integrated manner with medical schools.
The integration of nature research and humanresearch is in transition, and I believe that such integration of various fields, not only forest therapy, will
become more important in the future.
Which forests would you recommend to overseasvisitors?
Certification of forests under the Forest Therapy Base
Scheme is based not only on scientific evidence produced by our research team, but also on the services
that each region can provide, specifically hard infrastructure, such as lodging, hospitals, and accessible
roads, and soft infrastructure or experiential activities, such as soba noodle-making and woodworking,box lunches and meals. Certified forests offer sample
courses for day trips and overnight trips.
My first recommendation is the Akasawa Natural
Recreational Forest in Nagano Prefecture. It is considered the birthplace of forest bathing in Japan andoffers a very high level of forest therapy activities. In

the spring and fall, the Akasawa Natural Recreation
Forest holds special forest bathing events. It also provides programs for visitors to enjoy with their children, such as forest railway rides and playing in theriver.
I would also recommend Okutama Town in Tokyo
because it is known as the area with the largest number of giant trees in Japan and is easily accessible fromthe Tokyo metropolitan area.
Chizu Town in Tottori Prefecture has also developed a high-quality forest therapy program, which has
been adopted as part of corporate training programs.
Tsubetsu Town in Hokkaido also offers various
programs that take advantage of the changing seasons,such as snowshoe hiking experiences1 and stargazing
programs.2
Japan is one of the most forested countries in theworld. When visiting Japan, be sure to enjoy the relaxing effects of the beautiful nature as well as the uniqueaspects of Japanese culture born from the naturalenvironment in each region.
1. Forest therapy program in which participants hike on snowshoes through snow-covered
mountains
2. Forest therapy program for stargazing in the forest

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