Natural environment lowers cortisol levels
Do you suffer from stress? Go into nature. The longer you stay in a natural and green environment, the further your cortisol level drops, write psychologists from the University of Michigan in Frontiers in Psychology. And if you are short on time, try to stay at least 20-30 minutes for a stay in a park or forests.
The researchers got 36 test subjects, who lived in a city, to spend at least 10 minutes three times a week in a natural environment for two months. The test subjects were not allowed to exercise intensively. Being active on a cell phone, nor reading or having a conversation were not allowed.
The researchers took a little saliva before and after the stay in nature, in which they determined the concentration of the stress hormone cortisol.
The time of day was an important determinant of cortisol levels. That makes sense, because the cortisol level gets lower and lower during the day. With every hour that time passes during the day, the cortisol level drops by around 12 percent. If the test subjects stayed in nature, the cortisol level dropped even faster. Then the cortisol level dropped by 21 percent per hour.
For people with little time, who want to achieve the greatest possible decrease in cortisol during the shortest exposure to nature, the researchers calculated the optimal 'dose' of exposure to nature. That was 20-30 minutes.
"Healthcare practitioners can use our results as an evidence-based rule of thumb on what to put in a nature-pill prescription", says first author MaryCarol Hunter in a press release. [sciencedaily.com April 4, 2019]
"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."
Frontiers in Psychology, 2019; 10 DOI: 10.3389/fpsyg.2019.00722.
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