"Forest therapy," sometimes called "forest bathing," comes from Japan, where researchers are studying the physiological impact of spending time in the woods. So far, research has indicated that it does have measurable health benefits - it can lower levels of salivary cortisol, the hormone that rises when we're under stress. It can also lower blood pressure and pulse rate and trigger a dramatic increase in the activity of natural killer (NK) cells, which are produced by the immune system to ward off infection and fight cancer. Japanese researchers have reported that spending three days in the forest increases NK activity by 50 percent, a beneficial effect that can last up to one month.
It isn't surprising that time spent in the woods can be calming, especially when you trade the sometimes jarring sounds, sights, and smells of city life for those of trees, birds and running water in forest streams. More specifically, one Japanese study showed that just gazing at forest scenery for 20 minutes reduced salivary cortisol levels by 13.4 percent, bringing them down to lower-than-average concentrations among city dwellers. One Japanese expert on forest therapy attributed some of the increased NK activity to inhalation of phytoncides, compounds in volatile oils given off by trees.
Enthusiasm for forest therapy in Japan has led to the designation of 31 forest therapy bases and four forest therapy roads in wooded areas where researchers have scientifically documented relaxing effects. Visitors to these areas can have free medical checkups, take breathing and aromatherapy classes, and, at some of the area, go on guided walks with experts on forests and health care. Additional forests and roads are expected to receive the designations in the next few years, and some Japanese companies now include coverage for forest therapy as part of their employee health plans.
I've written on this site and in my Spontaneous Happiness book and website about the importance of connecting with nature. We are creatures of nature and cannot enjoy optimum physical or emotional well-being if we have too little contact with it. Biologist E.O. Wilson coined the term biophilia, which means "love of life or living systems" to describe this innate human need. I believe it to be as real as our needs for food, sex, love and community.
Forest therapy seems to offer significant health benefits that you may be able to capture if you let nature into your awareness as often as you can, any way you can. Watch the ever-changing shapes of clouds, admire trees, listen to the wind, look at the moon, at birds, at mountains. And when you do, be aware that you are part of nature, connected through it to something much larger than yourself that transcends and will survive you.
Andrew Weil, M.D.