Time outside: more than its own reward?

In Shinrin Yoku, you simply immerse yourself in nature-- no hiking, no exercising, just being. 

Japanese officials spent $4 million dollars studying the mind and body affects of this "eco-therapy." Qing Li, a professor in Tokyo, examined the amount of human natural killer (NK) cells in each participants immune system before and after exposure to forest bathing. These cells respond to viral-infected cells and cancer-formation cells creating healthy immune systems. The results showed an increase in NK cell activity following participants activity in forest-bathing. This is due to the essential oils found in wood and plants, referred to as phytoncide. This oil is secreted from trees and other plants to naturally protect themselves from germs and other predators. When surrounded by trees and other plants in a forest, Phytoncide is breathed in and shown to positively boost your immune system. 

A related study in Japan's Chiba University found that stress cortisol levels, heart rate, and blood pressure were all positively affected by forest-bathing as compared to time spent in city landscapes.

In addition, forest-bathing has been proven to soothe the mind and spirit, as well as the body. 498 healthy volunteers were surveyed twice before and twice after their experience forest-bathing and showed as result, reduced scores in hostility and depression and heightened levels of liveliness. 

For further detail: 

https://qz.com/804022/health-benefits-japanese-forest-bathing/

https://www.washingtonpost.com/news/to-your-health/wp/2016/05/17/forest-bathing-is-latest-fitness-trend-to-hit-u-s-where-yoga-was-30-years-ago/?utm_term=.46af6dfdd3a0

http://www.publichealthjrnl.com/article/S0033-3506(06)00146-6/abstract?cc=y=

http://www.shinrin-yoku.org/