Being in Nature for 20 Minutes Can Reduce Stress Hormones

Allowing yourself a 20-minute nature experience can significantly lower your stress hormone levels, according to new research published in the journal Frontiers in Psychology.

“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,” said lead author Dr. MaryCarol Hunter, an associate professor at the University of Michigan.

“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.”

The researchers said health care practitioners can use this finding as a guideline for prescribing “nature pills” to their patients. Nature pills can be a low-cost solution to reduce the negative health impacts rising from growing urbanization and indoor lifestyles dominated by screen viewing.

For 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 the stress hormone cortisol were measured from saliva samples before and after taking 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 that in the opinion of the participant, made them feel like they’ve interacted with nature,” said Hunter.

“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.”

“Building personal flexibility into the experiment, allowed us to identify the optimal duration of a nature pill, no matter when or where it is taken, and under the normal circumstances of modern life, with its unpredictability and hectic scheduling.”

The findings show that just a 20-minute nature experience was enough to significantly reduce cortisol levels. But if you spent a little more time immersed 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.

“Health care practitioners can use our results as an evidence-based rule of thumb on what to put in a nature-pill prescription,” said Hunter. “It provides the first estimates of how nature experiences impact stress levels in the context of normal daily life. It breaks new ground by addressing some of the complexities of measuring an effective nature dose.”

Hunter hopes this study will form the basis of further research in this area.

“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. 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.”