“We know that spending time in nature reduces stress, but until now it was unclear how much is enough, how often to do it, or even what kind of nature experience will benefit us,” says Dr. Mary Carol Hunter, an Associate Professor at the University of Michigan and lead author of this research. “Our study shows that for the greatest 36 , in terms of efficiently lowering levels of the stress hormone cortisol, you should spend 20 to 30 minutes sitting or walking in a place that provides you with a sense of nature.” Hunter and her colleagues designed an experiment that would give a realistic estimate of an effective dose. Over an 8-week period, participants were asked to take a nature pill with a duration of 10 minutes or more, at least 3 times a week. Levels of cortisol, a stress hormone, were 37 from saliva samples taken before and after a nature pill, once every two weeks. Participants were free to choose the time of day, duration, and the place of their nature experience, which was defined as anywhere outside 38 , in the opinion of the participants, made them feel like they’ve interacted with nature. There were a few constraints to minimize factors known to influence stress: take the nature pill in daylight, no aerobic exercise, and avoid the use of social media, Internet, phone calls, conversations, and reading. To 39 busy lifestyles, the experiment accommodated day to day differences in a participant’s stress status by collecting four snapshots of cortisol change due to a nature pill. The data revealed that just a twenty-minute nature experience was enough to significantly reduce cortisol levels. But if you spent a little more time 40 in a nature experience, 20 to 30 minutes sitting or walking, cortisol levels dropped at their greatest rate. After that, additional de-stressing benefits continue to add up but at a slower rate.