The Science of Forest Therapy | How to Reset Your Mind and Body with Nature's Power

What is Forest Therapy? | Nature's Healing Power Proven by Science

Forest therapy refers to efforts to maintain and improve physical and mental health through forest environments. The Japanese concept of "forest bathing (Shinrin-yoku)" was proposed in 1982 by Toshihide Akiyama, then director of the Japan Forestry Agency, and is now the subject of scientific research worldwide, recognized internationally as a health practice with medical evidence.

Pioneering research scientifically supporting the effects of forest therapy includes a series of studies by Professor Li Qing of Nippon Medical School. Research has reported that the activity of NK cells (natural killer cells) in participants who completed a 2-night, 3-day forest bathing program increased by approximately 50%, with the effects sustained for about one month. NK cells are immune cells that attack cancer cells and virus-infected cells, and this discovery was groundbreaking in demonstrating that forest bathing contributes to enhanced immunity.

Additionally, research by Professor Yoshifumi Miyazaki of Chiba University shows that merely spending 15 minutes in a forest environment reduces cortisol, a stress hormone, by approximately 16%, with reductions in blood pressure, decreased heart rate, and increased parasympathetic nervous system activity confirmed. Multiple studies have demonstrated that compared to urban environments, forest environments produce significantly higher psychological relaxation effects.

The Power of Phytoncides | Healing Substances Released by Trees

One of the key factors creating the effects of forest therapy is "phytoncides." Phytoncides are a collective term for volatile organic compounds released by trees, with terpenes such as α-pinene, limonene, and camphene as their main components. Originally produced by trees to protect themselves from pests and pathogens, when humans inhale phytoncides, they have the effect of regulating the autonomic nervous system and enhancing immune function.

Phytoncide concentration varies by tree species. Evergreens such as Hinoki cypress, sugi cedar, and camphor tree particularly emit high amounts, with the highest concentrations occurring on summer mornings. On days with temperatures of 20–25°C and higher humidity, airborne phytoncide concentrations increase, making the forest on the morning after the rainy season ends an ideal environment.

Interestingly, phytoncide effects are exerted even without passing through the sense of smell. They are absorbed through the skin and taken into the bloodstream through gas exchange in the lungs, affecting the entire body. Therefore, one can benefit from forest therapy even while wearing a mask for hay fever. However, research also shows that deliberately taking in phytoncides through deep breathing enhances the relaxation effect.

Forest Therapy Bases Nationwide | Certified Healing Forests

Japan has 65 designated "Forest Therapy Bases" and "Forest Therapy Roads" nationwide (as of 2025). These are certifications granted by the non-profit organization Forest Therapy Society to forest areas that have scientifically demonstrated physiological relaxation effects, providing quality assurance distinct from typical forest parks.

In the Tohoku region, "Buna Forest Onyoku Heiratai" in Oguni, Yamagata Prefecture is popular. The walking trail surrounded by ancient beech trees over 300 years old is a gentle one-way course of approximately 2 km, walkable without difficulty even for beginners. "Healing Forest" in Shinano, Nagano Prefecture was the first forest therapy base to be certified in Japan and remains a pioneering destination, with approximately 20,000 annual visitors. Dedicated forest medical trainers are stationed there and provide forest therapy programs based on medical prescriptions.

In the Tokyo area, the "Okutama Forest Therapy Road" in Okutama, Tokyo is easily accessible. Approximately 2 hours from Shinjuku, the forest walking course along the Tamagawa River offers varied scenery. Entry is free for self-guided walks, with guided programs ranging from ¥3,000 to ¥8,000. Overnight retreat plans are also offered in various locations, typically ranging from ¥15,000 to ¥30,000 for 2 days and 1 night.

Practicing Forest Therapy for Maximum Effect

To maximize the effects of forest therapy, there are several tips for how to walk and spend time in the forest. The most important is to "walk slowly." Rather than at a typical hiking pace, walk at approximately 1–2 km per hour while directing awareness to all five senses. Feel the texture of the ground beneath your feet, listen to the sound of the wind blowing through the trees, and deeply inhale the scents of the trees and soil.

A technique called "five-senses meditation walk" is particularly effective. For the first 10 minutes, focus on sight and observe the colors of leaves and the play of dappled sunlight. For the next 10 minutes, focus on hearing and listen to bird songs, the sound of streams, and the sound of wind. Next spend 10 minutes on smell, then touch, switching through each sense one by one as you walk, allowing you to enter a deep state of mindfulness.

A technique called "passive forest bathing," in which you spend more than 20 minutes sitting in the forest, is also recommended. Simply lying in a hammock or on a leisure sheet and looking up at the treetops activates the parasympathetic nervous system. Research has confirmed significant reductions in cortisol levels from merely sitting quietly in the forest for 20 minutes. You may also combine reading or napping.

Ideally, visit the forest 1–2 times per month for 2–4 hours each time. Even a weekend walk through a nearby forest park is sufficient. Persistence is key—most people notice improvements in sleep quality, stable blood pressure, and enhanced mood after continuing for three months or more.

Incorporating "Mini Forest Bathing" Into Your Daily Life

For those who find it difficult to visit the forest regularly, there are ways to partially benefit from forest therapy in daily life. Even a slow 15–20 minute walk through a park near your home or an avenue lined with street trees can have stress-reducing effects in environments with high green view rate (the proportion of green in your field of view).

It is also possible to introduce phytoncides indoors. Diffusing essential oils of Hinoki cypress or sugi cedar can reproduce an air environment similar to that within a forest. Hinoki oil, which has α-pinene as its main component, can be purchased for approximately ¥1,500–3,000 for 10 ml, and research reports that using it in the bedroom before sleep improves sleep quality.

Placing houseplants indoors is also recognized as effective as "green therapy." NASA (National Aeronautics and Space Administration) research has confirmed that indoor plants remove harmful substances from the air, with multifaceted health benefits. Multiple studies show that simply placing one or two plants in an office contributes to improved concentration and stress relief.

Forest therapy is a simple health practice that requires no special equipment or techniques—you need only immerse yourself in the forest to begin. Japan is one of the world's leading forest nations, with approximately 67% of its land covered in forests, with healing spaces within reach everywhere. SOROU.JP regularly updates information on forest therapy spots throughout the country, so please visit a forest on your next day off.