Spending just twenty minutes in a place that makes you feel in contact with nature can significantly lower your stress levels, say scientists who recommend that 'nature-pills' can have a measurable effect on our well-being.
The study, published in the journal Frontiers in Psychology, has established for the first time the most effective dose of an urban nature experience.
"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 MaryCarol Hunter, an associate professor at the University of Michigan in the US.
"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 in a statement.
Nature pills could be a low-cost solution to reduce the negative health impacts stemming from growing urbanisation and indoor lifestyles dominated by screen viewing.
To assist healthcare practitioners looking for evidence-based guidelines on what exactly to dispense, Hunter and her colleagues designed an experiment that would give a realistic estimate of an effective dose.
Over an eight-week period, participants were asked to take a nature pill with a duration of 10 minutes or more, at least three times a week.
Levels of cortisol, a stress hormone, were measured 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 that in the opinion of the participant, made them feel like they've interacted with nature," Hunter said.
"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," she said.
"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," she added.
To make allowances for busy lifestyles, while also providing meaningful results, the experimental design was novel in other aspects too.
The data revealed that just a twenty-minute nature experience was enough to significantly reduce cortisol levels. However, 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.
"Healthcare 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," she said