Scientists in Japan have been reporting on the immunopotentiating and stress-relieving benefits of shinrin-yoku, or forest bathing, since 1982, but only recently has the trend crossed the ocean. In a new spin on the ‘treatment’, scientists from the Rotman Research Institute at Baycrest in Toronto, report on the ability of a 50-minute walk in a park to improve performance on a cognitive task. The study, led by research fellow Marc Berman, will be published later this year in Journal of Affective Disorders.
Shinrin-Yoku, or Forest Bathing
In one of the Japanese studies, researchers found that after a three day and two night trip of forest bathing, including two to four hours of walking per day in the forest, eleven of twelve subjects showed increases in natural-killer (NK) cell activity – powerful lymphocytes known to fight off infection and halt cancer growth. The average increase was about 50%, and expression of other immune cells and intracellular anti-cancer proteins increased as well. Of course, as these twelve subjects were all men who regularly worked at large companies in Tokyo, one might quite obviously ask whether or not three days anywhere other than the office would have a similar effect.
In answer, the same researchers followed up the initial study with a second study, which compared subjects who walked for two to four hours daily on a three day trip in the wood to those who walked for two to four hours daily on a three day trip in a city. The city visiting subjects did not in fact show increases in immune cells or intracellular anti-cancer proteins, nor did they show the same decrease in the stress hormone adrenaline as those experiencing the effects of skinrin-yoku.
It is worth noting, however, particularly in light of recent focus on fraudulent research, that the studies cited above were funded in part by Japan’s Forestry and Forest Products Research Institute.
More recently, Marc Berman and fellow scientists investigated the hypothesis that forest bathing or going for a walk in the woods would help people give ‘voluntary attention’ a break, and thus improve cognition. Turned out they were right: 19 subjects, all suffering from Major Depressive Disorder, showed significant improvements in a cognitive test measuring memory-span administered after a 50 minute walk in the woods compared to a similar test administered before. A similar effect has been demonstrated in non-depressed individuals before.
Berman suggests a variety of hypotheses to explain why forest bathing is so good for our brains, but the most important thing, according to him, is to give the mind a chance to ‘wander aimlessly and be engaged – involuntarily but gently – by your surroundings.’
The Globe and Mail – Why is walking in the woods so good for you?