Forest Medicine — The Science Behind How I Cope With Depression

Tara Tiger Brown
8 min readMay 25, 2019


About 6 months after I moved to Tokyo from Los Angeles the honeymoon phase of living in Japan wore off and I transitioned into what is referred to as the “rejection phase” of culture shock. In other words, I was stressed and depressed and I wanted to go home. The excitement I used to feel when at Shibuya station became my worst nightmare during my daily commute across the busiest intersection in the world to the Japanese language school where I frequently wished that I could shrink myself down to the size of Pikachu so that my instructor wouldn’t call on me in class. I tried to use social media to feel connected to my friends and family but out of a feeling of shame or embarrassment, I didn’t want to convey that Japan was making me sad. Everything that I was accustomed to being quick and easy like directing the Amazon delivery person to leave a package at the front door, now required a level of patience that was beyond me thanks to overly complicated bureaucracy. My options felt limited to none; I couldn’t move home, medicinal options that many rely on in California and Canada were not available to me, and English-speaking counselors were not easy to find. At a loss for a solution, I turned to familiar territory, education + science, and decided to learn how to be happy.


Through my research (including taking The Science of Happiness course which I highly recommend), I discovered that the answers were literally in my backyard. Forest Bathing (Shin-rin Yoku) originated in Japan in the 1980s and is the practice of leisurely spending time in the forest while opening up all your senses. It has become popular in the US and other parts of the world and takes on various forms but the goal is to reduce stress by spending time in a natural space.

The associated interdisciplinary science of Forest Medicine, is the study of the effects of forest environments on human health, including:

  • Physical factors (air temperature, humidity, sounds, etc.);
  • Chemical factors (volatile organic compounds);
  • Psychological factors (subjective evaluation of the forest environment).

Essentially, medical doctors are researching the effects that the forest environment has on people before and after they partake in forest bathing.

Uenomura, Gunma — Japan Forest Therapy Base

Preventative Medicine Against Lifestyle-related Diseases

Thanks in part to the International Society of Nature and Forest Medicine (INFOM), Board Vice-President Dr. Qing Li’s books, Forest Bathing and Forest Medicine and Dr. Yoshifumi Miyazaki’s book, Shin-rin Yoku, and subsequent discussions with both of them, my understanding of forest bathing and forest medicine have become greatly expanded. More than 70% of Japan is forested so it is a natural place culturally and logistically for this research and practice to take place.

The current research is focused on preventative measures against lifestyle-related diseases, much like meditation, exercise, good sleep habits and eating a balanced diet can provide. INFOM doesn’t make any claims that Forest Bathing can be considered a cure for diseases like cancer.

To date, Forest Medicine researchers have proven that forest-bathing provides the following benefits:

  • Lowers the stress hormones cortisol and adrenaline;
  • Suppresses the sympathetic or “fight or flight” system;
  • Enhances the parasympathetic or “rest and recover” system;
  • Lowers blood pressure and increases heart-rate variability.

Research also shows that forest bathing can:

  • Help you sleep better;
  • Improve your mood;
  • Make you less aggressive and hostile;
  • Boost your immune system.
Tara Tiger Brown — INFOM — Pre-Forest Bathing Medical Check

Frequency Of Practice For Optimal Benefits

Dr. Li and his colleagues at INFOM have focused much of their research on the immune system, in particular, natural killer (NK) cells that can attack and kill unwanted cells. In order to increase and maintain NK cells, the recommendation is to spend 3 days, 2 nights in the forest for a lasting benefit of 30 days. If you spend one day, the benefits will last for approximately one week.

For mood enhancing, they have seen improvements after spending 2 hours in the forest. Bonus for me — women’s moods seem to be affected more by forest-bathing than men’s. These are subjective observations based on using a scoring system called POMs, but by using a mood taking app or writing in a journal, this is something that anyone can experiment with for themselves.

Tara Tiger Brown and Dr. Qing Li

Opening Up Your Senses

In addition to choosing an optimal forest bathing environment, the most important aspect of forest bathing is letting nature in through all of our (traditionally recognized) five senses plus our sixth sense:

  1. Sight
  2. Hearing
  3. Taste
  4. Smell
  5. Touch
  6. State of Mind (may also be referred to as extrasensory perception or an anomalous experience)


In his book, Biophilia, E.O. Wilson popularized the idea that humans innately want to connect to nature and other forms of life. It’s why you see companies like Amazon and Microsoft creating spaces for their employees to lower their stress (and be more productive) or the indoor park at Singapore Airport to make traveling more pleasant. Fractal patterns in nature can reduce our stress by 60%. We are visually fluent in patterns of nature and because we are good at it, it relaxes us. Green and blue colors are comforting to us. At a primal level, we associate green with nearby water and a food source. Looking at nature can increase our levels of anti-inflammatory cytokines — proteins that tell our immune system to work harder.


The sounds in nature that humans tend to like the most are water, wind, bird chatter and bird song. People are most sensitive to sounds between 2,500–3,500 Hertz which is the same range that birds sing in. There is evidence that humans are losing their ability to hear nature sounds because of noise pollution and shutting out the environment around us by wearing headphones, which is why you should not use headphones when spending time in a natural environment or green space.


In the context of forest bathing, the sense of taste is mainly associated with eating wild mountain food (forest food). Some of the foods eaten during a forest bathing experience in Japan include sansai or spring mountain vegetables such as warabi mochi, kogomi fiddlehead ferns, and tara no me from an Angelica tree.


Fifty percent of positive forest bathing results come from smells you take in. Geosim is a chemical compound that gives beets, lettuce, and mushrooms an earthy taste and contributes to the scent called petrichor, when rain falls after a dry spell and the oils stored in soil and rock are released into the air. Humans are very sensitive to geosim and can detect it at low levels because it was the chemical that helped us find food. The French call this terroir or taste of the region in reference to wine, cheese, and chocolate.

Plant chemicals called phytoncides are the forest’s natural aromatherapy. Research, especially out of South Korea, focuses on the oils that are emitted from trees. In addition to being a defensive mechanism for trees, they benefit us. For example, the citrus fragrance of the phytoncide D. limonene has been shown to be more effective than antidepressants for lifting your mood.

Japanese forest bathing smells include white cypress, hinoki wood, and leaf, rosemary, cedarwood, eucalyptus, and pine.


The Earth has natural low-level electrical charges that are beneficial to us. We evolved in nature and we have a biological need to connect to it, and yet we have put a layer between us and nature by wearing shoes, paving over top of it, and placing flooring over the ground. What we may deem to be a protective layer, may, in fact, be detrimental to our health.

Mycobacterium vaccae is a bacteria that occurs naturally in soil and can boost our immune system and increase happiness. When you dig in the dirt or eat vegetables plucked from the ground, you ingest m. vaccae.

State of Mind

Walking in the forest gives our mental resources a break; it clears our mind and helps us to think. We can remember 20% more when we go for a walk among trees as opposed to the city. It boosts our problem-solving ability and increases our creativity by 50%.

Forest Medicine Certification

I am now the proud owner of a Certificate of Completion in Forest Medicine from INFOM. I received my certification in May 2019 at Uenomura, Gunma, Japan forest therapy base.

I am not a medical doctor, and I do not claim to be practicing medicine, but I understand the practice of forest bathing, the research behind forest bathing, the types of medical testing done before and after to track changes, how environmental factors can affect the practice, the optimal setting and conditions, and the recommended time to spend in the forest each month to reach maximum benefits.

Tara Tiger Brown — INFOM Forest Medicine Certificate

Transparent and Open Forest Environmental Monitoring

My primary area of focus is to connect environmental data to the practice of spending time in the forest, (whether you refer to it as forest bathing or simply a nature walk), compared to life outside a forest setting, and make the data requirements and data transparent. By correlating health standards for pollutants — particulate matter, light, noise, etc. and applying those to areas where forest bathing and similar practices are being conducted, we will better be able to establish a baseline for forest therapy bases, track environmental changes over time, and research how the environmental factors affect us. Ultimately I would like to see even the smallest of forested spaces to be recognized as beneficial whether they are on government or private land, with the end goal that we gain a greater connection to trees, and keep them in the ground.

More Trees Please

In the course of our busy lives, we have deprioritized our health. We ignore the intuition that tells us to tear ourselves away from our computer and go outside to enjoy the beautiful day. We drown out the memories of our parents telling us to go outside because it’s good for us. We scroll past the headlines that warn us that spending too much time on our devices is making us unhappy. We seek out a gadget when our doctor tells us to reduce our blood pressure. We shut off the notification for the tenth time in a row reminding us to stand up and walk around. We grab our mobile phones the moment we wake up and fall asleep with them cradled in our hands only to be awoken a few hours later to our screen lighting up with a stream of messages and reminders that we decide to take care of right then so we can go back to sleep.

Despite medical and technological advancements (or perhaps because of them), we have lost sight of one of the easiest and most accessible way to manage our health — spending time in natural green spaces.

After researching what makes me feel happy and healthy, and medical proof that spending time in a forest environment improved my physical and mental health, the answer is clear, more trees, please.

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Tara Tiger Brown

Developing programs that intersect the environment, education, and well-being. | Founder @lamakerspace @kithub | 🇨🇦 🇺🇸 🇯🇵