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Forest bathing is the practice of taking a short, leisurely visit to a forest for health benefits. The practice originated in Japan where it is called shinrin-yoku (森林浴) in Japanese (it is also called sēnlínyù (森林浴) in Mandarin and sanlimyok (산림욕) in Korean).
Studies in Japan have measured changes in immune markers and stress hormones in people who regularly walked in specific forests in Japan. In addition, people with diabetes but not taking insulin found substantial benefits by lowering blood glucose levels.
A forest bathing trip involves visiting a forest for relaxation and recreation while breathing in volatile substances, called phytoncides (wood essential oils), which are antimicrobial volatile organic compounds derived from trees, such as α-Pinene and limonene. Incorporating forest bathing trips into a good lifestyle was first proposed in 1982 by the Forest Agency of Japan. It has now become a recognized relaxation and/or stress management activity in Japan.
There has been interest in forest bathing in the US.
Beginning in 2004, studies have been done by Yuko Tsunetsugu, Bum-Jin Park, and Yoshifumi Miyazaki to analyze the effects of Shinrin-yoku on physical and mental health, calling it the "Therapeutic Effects of Forests." Their work focused on how natural settings affected the senses of sight, sound, smell, and touch. A preliminary analysis done in a laboratory took place before performing the field study in an actual forest.
On the analysis for sight (visual stimulation), test subjects were shown two different scenery on display screens while their pulse and blood pressure were being monitored, a grey screen was used as control. A photograph of "Sakura" blossoms were shown, followed by a photograph of people walking in a forest, Shinrin-yoku. The results showed that Sakura stimulated both pulse rate and blood pressure. The researchers speculated that this was due to the excitement that came with the flowers blooming. On the other hand, the Shinrin-yoku image caused a decrease in blood pressure in comparison to both the Sakura image and the control.
The sound analysis (auditory stimulation) measured brain activity and systolic blood pressure while the test subjects listened to a mechanical turbine and that of a water stream. The turbine sounds increased systolic blood pressure, whereas the stream had no effect. Further research was later done to clarify the discrepancies between variables such as age, physical health, dental health, and other possible determinate factors.
The smell analysis (olfactory stimulation) was done with the testing of three different tree scents commonly found in Japan. In relation to phytoncides, it is speculated that smells associated with trees/forests would stimulate the most physiological change. The first sample was of Japanese cedar (Cryptomeria japonica), which resulted in a decrease both blood pressure and activity in the prefrontal cortext. The second sample was of Hiba (Thujopsis dolabrata) oil, which is commonly used to treat anxiety, depression, and kidney dialysis. The results of the test showed that the Hiba oil significantly stimulated the nervous system. The third sample was of the smell of Taiwan cypress (Chamaecyparis taiwanensis), which increased the both productivity and concentration. The researchers speculated that the increase in concentration was due to relaxation caused by the Taiwan cypress essential oil.
Finally, the touch analysis (tactile stimulation) was carried out by an experiment in which the test subject was given a room temperature metal plate, a plate made of oak that was cold, and an oak plate covered in a thick layer of paint. The metal plate and the oak plate covered in thick layers of paint aroused uneasy feelings and resulted in a significant increase in blood pressure. The cold oak plates on the other hand gave pleasant results, leading researchers to conclude that woodiness is pleasant to human nature regardless of temperature.
An on-field study was done in Chiba Prefecture, Japan, where subjects took 20 minute walks on each in the Seiwa Prefectural Forest Park, which is mainly oak trees, and the control site of Chiba Station. The subjects showed a much lower hemoglobin concentration when walking in the oak forest as opposed to Chiba Station. The final results also showed an increase in concentration and lowered stress hormones when the subjects were in the forest area.
A 2010 research review found that forest environments promoted lower concentrations of cortisol, lower pulse rate, lower blood pressure, greater parasympathetic nerve activity, and lower sympathetic nerve activity than city environments.
Forest environments have been found to be advantageous with respect to acute emotions, especially among those experiencing chronic stress.
A test was done in the late 1990's by the Department of Gerontotherapeutics at Hokkaido University School of Medicine on 87 test subjects who were non-insulin dependent diabetic patients. The task required patients to take walks of either 3 km, which took 30 minutes to complete, or 6 km, which took one hour to complete, in a forest, in which blood samples were taken periodically. The test was implemented 9 times within 6 years and the results showed that the Shinrin-yoku significantly benefited the health of diabetic patients, lowering blood glucose levels as far as 38.9% for 3 km walks and 40.0% for 6 km walks.
General benefits of being outdoors in natureEdit
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