Instead of sitting at your desk, a lunchtime stroll through a park is one of the most effective stress-lowering treatments that a doctor can prescribe, new research suggests.
This research was conducted by a team of scientists led by Dr Mary Carol Hunter, an associate professor at the University of Michigan, and has been published in the scientific journal Frontiers in Psychology. Communing with nature has long been recognised as restorative but now scientists claim to have worked out the optimum daily dose.
“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 Hunter. “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 results from the study indicate that spending 20 to 30 minutes in surroundings that made a person feel connected to nature, lowers stress hormones by about 10%, enough to improve their feeling of well-being. ‘Nature pills’, as the experience is often referred to by healthcare practitioners, could be a low-cost solution to reduce the negative health impacts stemming from growing urbanisation and indoor lifestyles dominated by screen viewing. In order to assist healthcare practitioners looking for evidence-based guidelines on what exactly to dispense, Dr Hunter and her colleagues designated an experiment that would give a realistic estimate of an effective dose.
For the study, participants were asked to take a ‘nature pill’ over an eight-week period, for a duration of 10 minutes or more, at least three times a week. To track the effects of this dose, levels of cortisol were measured from saliva samples taken before and after the prescribed nature experience, 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,” Dr Hunter explained. She further added, that there were a few additional constraints to minimise factors known to influence stress such as taking the nature pill in daylight hours, no aerobic exercise and avoiding use of social media, Internet, phone calls, conversations and reading.
This particular experiment allowed participants to make allowances for their busy lifestyles by providing them with the freedom to choose an appropriate time slot for their nature experience. This novel experimental design also allowed researchers to gather meaningful results. “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,” said Dr Hunter.
The study accommodated for day-to-day differences in a participant’s stress status by collecting four snapshots of cortisol change affected by the prescribed nature experience. It also allowed researchers to identify and account for the impact of ongoing, natural drop in cortisol level as the day progresses, making the estimate of effective duration more reliable.
The collected data revealed that just a 20-minute nature experience was enough to significantly reduce cortisol levels. But if you were to spend a little more time immersed in a nature experience, i.e., 20 to 30 minutes sitting or walking, cortisol levels dropped at their highest 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 to thumb on what to put in a nature pill prescription,” says Dr 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.”
Dr Hunter and her colleagues hope that this study will form the basis of further research in this area. They are hoping that their experimental approach can be used as a tool to assess how age, gender, seasonality, physical ability and culture can influence the effectiveness of nature experiences on well-being. Dr Hunter believes that this will allow for customised nature pill prescriptions, as well as a deeper insight on how to design cities and well-being programmes for the public.
