It's being studied in Japan:
[University of Chiba's Yoshifumi 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 says. "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."
To prove it, Miyazaki has taken more than 600 research subjects into the woods since 2004. He and his colleague Juyoung Lee, also of Chiba University, have found that leisurely forest walks, compared with urban walks, yield a 12.4 percent decrease in the stress hormone cortisol, a seven percent decrease in sympathetic nerve activity, a 1.4 percent decrease in blood pressure, and a 5.8 percent decrease in heart rate. On subjective tests, study participants also report better moods and lower anxiety.
(Photo: "Mononoke forest, Yakushima island" by Casey Yee)
The Dish 