“In every walk in nature man receives much more than he seeks.” JOHN MUIR

The best weapon to combat stress is nature. According to the University of Michigan study, published in Frontiers in Psychology, spending at least 20 minutes a day in contact with green would be enough to reduce the main stress hormone, cortisol.

“We knew that spending time immersed in nature has anti-sterss effects, but until now it was not known in what ‘doses’ and how to ‘take on’ contact with nature,” says MaryCarol Hunter, who led the work. “Our study shows that the greatest results are achieved by spending 20 to 30 minutes sitting or walking anywhere that conveys a sense of closeness to nature.”

The research was conducted on a group of volunteers who for eight weeks had to spend time in natural places, such as a park, but without playing sports, conversing with friends or engaging in other activities that may in themselves have an influence on stress. Volunteers were repeatedly measured for the concentration of cortisol in their saliva. It was found that the hormone decreases from 20 minutes spent in contact with nature; the concentration drops in proportion to the time spent until a maximum drop at 30 minutes of immersion in nature.

“Clinicians can use our results as an evidence-based rule to determine how to prescribe contact with nature,” Hunter says. “Our study provides the first estimates of how nature experience impacts stress levels in the context of normal daily life.”