Coined by the Japanese Ministry of Agriculture, Forestry and Fisheries in 1982, shinrin-yoku literally translates to “taking in the forest atmosphere” or “forest bathing,” and refers to the process of soaking up the sights, smells and sounds of a natural setting to promote physiological and psychological health.
Forest bathing has become a recognized relaxation and/or stress management activity in Japan, where forest therapy modalities are integrated into their medical system and are covered by insurance.
Dr. Qing Li of Tokyo’s Nippon Medical School explained: “In 1982, the Forest Agency of Japan first proposed a new movement called “forest bathing trip” as a healthy lifestyle. Now it has become a recognized relaxation and/or stress management activity in Japan. Nature and Forest Medicine will prevent people from cancers and lifestyle-related diseases such as heart disease, diabetes, cerebrovascular disease, depression and hypertension. I suggest working men and women take a two-night/three-day trip to forests for obtaining the better benefits.”
Forest therapy was pioneered by Yoshifumi Miyazaki, a physiological anthropologist and vice director of Chiba University’s Center for Environment, Health, and Field Sciences. Miyazaki believes that because humans evolved in nature, it’s where we feel most comfortable, even if we don’t always know it. “Throughout our evolution, we’ve spent 99.9 percent of our time in natural environments,” he reported on Outside magazine. “Our physiological functions are still adapted to it. During everyday life, a feeling of comfort can be achieved if our rhythms are synchronized with those of the environment.”
Japan is a world leader in the accumulation of scientific data on forest medicine research. The government has funded about $4 million in forest-bathing research since 2004.
2014 review- Forest Medicine Research in Japan – There has been growing attention on the effects of forest on physiological relaxation and immune recovery, particularly in forest medicine research, from a perspective of preventive medicine. Forest therapy can decrease blood pressure, heart rate, sympathetic nerve activity, and levels of stress hormones, such as urinary adrenaline and noradrenaline, and can increase parasympathetic nerve activity, suggesting its preventive effect on hypertension. Forest therapy can also decrease the scores for anxiety, depression, anger, and fatigue.
2010 study – The Physiological Effects of Shinrin-yoku (taking in the forest atmosphere or forest bathing): evidence from field experiments in 24 forests across Japan. (Environmental Health and Preventive Medicine journal). New results from field experiments conducted in 24 forests across Japan. In order to clarify the physiological effects of Shinrin-yoku, we conducted field experiments in 24 forests across Japan. In each experiment, 12 subjects (280 total; ages 21.7 +/- 1.5 year) walked in and viewed a forest or city area.
The results show that forest environments promote lower concentrations of cortisol, lower pulse rate, lower blood pressure, greater parasympathetic nerve activity, and lower sympathetic nerve activity than do city environments.
2007 study- Physiological Effects of Shinrin-yoku (taking in the atmosphere of the forest) in an old-growth broadleaf forest in Yamagata Prefecture, Japan. (Journal of Physiological Anthpology) The physiological effects of “Shinrin-yoku” (taking in the atmosphere of the forest) were examined by investigating blood pressure, pulse rate, heart rate variability (HRV), salivary cortisol concentration, and immunoglobulin A concentration in saliva.
The findings were as follows. In the forest area compared to the city area, 1) blood pressure and pulse rate were significantly lower, and 2) the power of the HF component of the HRV tended to be higher and LF/(LF+HF) tended to be lower. Also, 3) salivary cortisol concentration was significantly lower in the forest area. These physiological responses suggest that sympathetic nervous activity was suppressed and parasympathetic nervous activity was enhanced in the forest area, and that “Shinrin-yoku” reduced stress levels.
Dr. Li suggests our immune NK (natural killer) cells are affected by “aromatic volatile substances,” otherwise known as scents, sometimes called phytoncides. These are the pinenes, limonenes, and other aerosols emitted by evergreens and many other trees. Scientists have identified 50 to 100 of these phytoncides in the Japanese countryside and virtually none in city air that’s not directly above a park.
To test the phytoncide theory, Li put 12 subjects in hotel rooms. In some rooms, he rigged a humidifier to vaporize stem oil from common Hinoki cypress trees; other rooms got nothing. The results? The cypress dwellers had a 20 percent increase in NK cells during their three-night stay and reported feeling less fatigued. The control group saw almost no changes. “It’s like a miracle drug,” said Li.
Japan has 48 official Forest Therapy trails. The goal is to designate a total of 100 Forest Therapy sites in the future. And South Korea has allocated $140 million into a new National Forest Therapy Center.