ScienceDaily (July 23, 2010) — "Many people," says Dr. Eeva Karjalainen, of the Finnish Forest Research Institute, Metla, "feel relaxed and good when they are out in nature. But not many of us know that there is also scientific evidence about the healing effects of nature." Forests -- and other natural, green settings -- can reduce stress, improve moods, reduce anger and aggressiveness and increase overall happiness. Forest visits may also strengthen our immune system by increasing the activity and number of natural killer cells that destroy cancer cells.
http://www.sciencedaily.com/releases/2010/07/100723161221.htm