ANN ARBOR, Mich. — Rough day? Step outside for a bit — it may be the strongest and fastest-acting medicine around. A new study finds that spending just 20 minutes walking or even simply sitting down somewhere outdoors that makes you feel more connected with nature can lower your stress hormone levels.
“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 lead author Dr. MaryCarol Hunter, an associate professor at the University of Michigan, in a media release. “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.”
Researchers have already started to call these 20-minute nature sessions “nature pills,” because they can be prescribed as stress reducers with predictable, measurable results. This natural medicine is a low-cost, yet effective, solution for the negative health implications from increasing urbanization and indoor, sedentary lifestyles in front of screens.
For the study, 36 healthy adults (33 women, 3 men) were recruited to spend at least 10 minutes or more in a natural environment three times each week over an eight-week period. Participants could take the breaks any time they wanted to better suit the unpredictable moments of our days that add sudden bursts of stress.
“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.” Hunter explains. “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.”
The researchers measured participants’ levels of the stress hormone cortisol via saliva samples, taken before and after each nature pill, once every two weeks. They found that 20 minutes was enough time to significantly reduce stress, but cortisol levels dropped even more dramatically if a person stayed for up to 30 minutes. After a half hour, the effect still continued, but not at such a significant pace.
Hunter and her team believe nature pills can be a real solution for those experiencing high stress.
“Healthcare practitioners can use our results as an evidence-based rule of thumb on what to put in a nature-pill prescription,” says 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.”
The study was published in the journal Frontiers in Psychology.