"Participants were free to choose the time of day, duration, and the place of their nature experience, which was defined as anywhere outside that in the opinion of the participant, made them feel like they've interacted with nature," lead author MaryCarol Hunter explained in a statement. "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."
In addition to accommodating the subjects’ busy lifestyles, the team also factored in the natural drop in cortisol levels that can occur naturally throughout the day.
After analyzing the results, they found having a 20-minute nature experience reduced cortisol levels. In fact, those who spent 20 to 30 minutes sitting or walking outside had the greatest decrease of cortisol levels.
“Our study shows that for the greatest payoff, 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 said.
The team said their findings provide the first estimates of how nature can impact our daily lives, and they hope healthcare providers take advantage of the evidence.
"Our experimental approach can be used as a tool to assess how age, gender, seasonality, physical ability and culture influences the effectiveness of nature experiences on well-being," Hunter said. "This will allow customized nature pill prescriptions, as well as a deeper insight on how to design cities and well-being programs for the public."