20 Minutes With Mother Nature Lowers Stress
“Study nature, love nature, stay close to nature. It will never fail you.”
These words were uttered by Frank Lloyd Wright, considered by many to be one of the finest architects in history. Wright was a man who devoted his career to crafting man-made structures that didn’t stand apart from nature, but became one with them. His designs were simple and enhanced the natural beauty of the surrounding environments.
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While it might seem odd that a man whose profession appears to be diametrically opposed to nature, Wright respected, appreciated, and, above all, recognized the value, importance, and necessity of it.
If one of the greatest architects in American history realized how essential nature is to the human condition, surely those of us who aren’t architects can appreciate its importance.
Unfortunately, today we spend less and less time enjoying the great outdoors due to a mix of farther commutes, longer work hours, and plain old laziness.
If you think that nature is better left to its own and you’re comfortable in a building, maybe the findings of a new study, which showed that just 20 minutes with nature can significantly decrease stress, will convince you to get outside and enjoy the great outdoors.
Researchers have known for quite some time that a stroll through nature helps relieve stress and tension, but until now science had not quantified the “ideal” amount needed to reap the benefits of time basking in the wonders of the outdoor world.
The latest study, Published in Frontiers, is the first to document the most “effective dose” of a nature “pill”.
Researchers assembled a test group via email announcements and flyers sent to the faculty and staff at the University of Michigan as well as members of several non-profit organizations in the Ann Arbor, MI area. 
Ideal candidates for the study, as described by the researchers, were normal, healthy adults, age 18 and over, who were interested in spending more time outdoors. Participants were self-selected and a total of 36 individuals (92% were female, mean age was ~45 years old) completed the trial.
Over an 8-week period, study participants were asked to have at least three “nature experiences” lasting a minimum of 10 minutes.
These “nature experiences” were defined by the team of researchers as:
“anywhere outside that, in the opinion of the participant, included a sufficiency of natural elements to feel like a nature interaction.” 
Subjects were allowed to select the time of day, location and duration of their nature experience based on the happenings of their daily life. During their romp through nature, there had the option to walk, sit, or do a combination of both, so long as they were outside for at least 10 minutes in nature.
Additionally, subjects were asked to avoid using smartphones, the internet, social media, reading, or having conversations. They were also advised to avoid aerobic exercise during their nature experience in order to limit any chance of an increase in endocannabinoids -- chemicals released by the body that stimulate the endocannabinoid system, affecting a wide range of physiological and cognitive processes including mood, memory, and appetite. 
To test the potential stress-relieving properties of the nature pill, researchers tracked two commonly used biomarkers of stress in salivary cortisol and salivary alpha-amylase.
As many of you probably know, cortisol is the body’s primary stress hormone released in times when we perceive or encounter a threat. Cortisol affects many metabolic pathways in the body involved with homeostasis, including immune function.
During acute stressors, such as a heavy set of squats, cortisol rises temporarily and then eventually returns to baseline. However, when we are chronically stressed (the way many people are these days), cortisol levels remain elevated a number of negative consequences have been found, including: [2,3,4]
- Decreased immune function
- Lower bone density
- Elevated blood pressure
- Increased body weight
- Impaired learning and memory
- Elevated cholesterol levels
- Increased risk of heart disease
- Lower testosterone levels
- Poor sleep
Basically, when you’re chronically stressed, everything in your body goes to hell in a handbasket.
Now, you might be wondering why the team of researchers used both salivary cortisol and amylase to track changes in stress biomarkers instead of just cortisol. The reason for this is that the two work via different pathways.
Cortisol is controlled by the autonomic nervous system which adjusts to stress using signals from the hypothalamic pituitary adrenal (HPA), while amylase is under the control of the sympathetic adrenal medullary (SAM) axis.
Additionally, amylase is produced by the digestive system and is released in response to both physical and psychological stressors. It has been used more and more in recent years to study the stress response of the sympathetic nervous system typically during “physically passive interventions” such as reading or listening to music.
Each study participant was responsible for collecting their own saliva samples, which had to be collected during daylight hours at least 1 hour after waking and be completed before sundown. No drinking, eating, or teeth-brushing could be done 30 minutes prior to collecting the saliva sample as this could disrupt the measurement of amylase.
Following the conclusion of the 8-week study, researchers collected all saliva samples, collated and processed the data. From their analysis, researchers documented that as little as 20 minutes experiencing nature could significantly reduce cortisol levels.
They did note that the longer an individual stayed in nature, the greater the drop in cortisol and stress they experienced. After the 30-minute mark of walking or sitting, additional stress-relieving benefits of nature pills continue to accumulate but at a slower rate.
Lead author of the study, Dr. Mary Carol Hunter, an Associate Professor at the University of Michigan, stated:
"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. 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 findings have led researchers to posit the notion that nature “pills” could be a low-cost, all-natural alternative to prescription medications for reducing stress and anxiety induced by modern man’s increasingly indoor, urbanized lifestyle that is dominated by artificial light and screen staring.
If you find that you are more easily stressed or spend increasingly longer periods of time in a stressed state, it’s worth putting everything on pause for 20 minutes, going outside for a walk, and allowing nature to put your worries at ease.
Life is too short as it is already. There’s no need to reduce your time anymore by being stressed out all the time.
What do you think of the findings of the latest study?
Do you feel more relaxed when out in nature?
If not, what steps do you take to help reduce stress and find balance?
Leave your comments down below!
1) Mary Carol R. Hunter, Brenda W. Gillespie, Sophie Yu-Pu Chen. Urban Nature Experiences Reduce Stress in the Context of Daily Life Based on Salivary Biomarkers. Frontiers in Psychology, 2019; 10 DOI: 10.3389/fpsyg.2019.00722
2) McEwen, B. S. (2008). Central effects of stress hormones in health and disease: Understanding the protective and damaging effects of stress and stress mediators. Eur. J. Pharmacol. 583, 174–185. doi: 10.1016/j.ejphar.2007.11.07t
3) Lupien, S. J., McEwen, B. S., Gunnar, M. R., and Heim, C. (2009). Effects of stress throughout the lifespan on the brain, behaviour and cognition. Nat. Rev. Neurosci. 10, 434–445. doi: 10.1038/nrn2639
4) Han KS, Kim L, Shim I. Stress and sleep disorder. Exp Neurobiol. 2012;21(4):141–150. doi:10.5607/en.2012.21.4.141
5) Daly, W., Seegers, C. A., Rubin, D. A., Dobridge, J. D., & Hackney, A. C. (2005). Relationship between stress hormones and testosterone with prolonged endurance exercise. European Journal of Applied Physiology, 93(4), 375–380. https://doi.org/10.1007/s00421-004-1223-1
6) Aizpurua-Olaizola, O., Elezgarai, I., Rico-Barrio, I., Zarandona, I., Etxebarria, N., & Usobiaga, A. (2017). Targeting the endocannabinoid system: future therapeutic strategies. Drug Discovery Today, 22(1), 105–110. https://doi.org/https://doi.org/10.1016/j.drudis.2016.08.005
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