It is well established that vitamin and mineral deficiencies can cause serious health problems. Without adequate micronutrients biochemical processes can become derailed and without adequate macronutrients—protein fat and carbohydrate—the physical structure of the body may be compromised as well. But what if deficiencies in other inputs—things completely unrelated to diet—also have detrimental effects on health? Might we see clinical value in the term “nature deficit disorder” and could “supplementing” with time in nature have a positive impact? A large body of research says yes.

It may well be that the human evolutionary experience has conditioned the body and brain to “expect” natural sensory inputs that are best experienced outdoors: the gentle lapping of waves against a beach; cheerful birdsongs; the sound of a breeze rustling the leaves in a tree; the invigorating scent of freshly cut grass; or the colorful sight of a wildflower meadow. Healthcare professionals should not overlook the potential these inputs have in boosting overall wellness. A wealth of evidence supports multiple mechanisms by which spending time in nature may support physical and mental health. The connections are so strong in fact that some researchers now call green space “vitamin G.”

Some individuals may not mind spending all day indoors under artificial lights looking at a computer or phone screen. For others though there may be an innate drive for exposure to natural elements and negative repercussions can occur when these elements are absent for an extended period of time. This seems to be especially true for psychological health. On an anecdotal level things like walking in a green or wooded space or watching a sunset over a lake seem to be quite relaxing. But we don’t have to rely on anecdotal evidence. On a more scientific level studies do indicate that contact with natural surroundings may be a low-cost way to support health—not to mention one that is free of adverse side-effects. This may be particularly true in urban areas where busy traffic noisy sirens and a stream of lights and sounds are the norm. “Forest medicine” may reduce blood pressure heart rate sympathetic nerve activity and levels of stress hormones (measured via urinary adrenaline and noradrenaline). Forest therapy is also known to decrease self-reported scores for depression anxiety fatigue and anger.

Spending time in green space is therapeutic enough that it can result in “psychological restoration” as one study’s authors phrased it. A possible benefit of more time in natural surroundings would be a reduction in stress hormones and a generalized better ability to cope with stressful life situations. Levels of cortisol and adrenaline are likely lower when one is lying in the grass and looking up at the stars compared to being behind the wheel in morning rush hour traffic in a major city.

If time in nature were a pharmaceutical drug its “active ingredients” would include exposure to negative air ions diverse environmental bacteria natural sights and sounds decreased air pollution and more. And reduced risk for such conditions as diabetes cancer anxiety depression cardiovascular disease allergies and migraines would be among the expected health outcomes. With claims like this if nature could be patented and sold by prescription it would be worth billions of dollars. Of course nature cannot be bottled and sold but fortunately unlimited doses are completely free! (That is after accounting for tax dollars that support public green spaces.) 

It’s possible that the connections between improved health and time spent in natural surroundings is due to the activities that tend to take place in those surroundings. That is people who have access to parks nature trails beaches and the like may be more inclined to walk regularly jog swim hike or play sports. Research suggests however that increased physical activity does not have a strong correlation with improved health among people who spend time in nature. Better perceived overall health as well as better mental health and fewer acute health complaints correlate more strongly with the stress-reducing effects and opportunities for increased socialization that green spaces provide rather than increased physical activity.

Other than using levels of stress hormones and perhaps generating questionnaires for individuals to self-assess their feelings of mental and emotional wellbeing it is difficult to quantify the intangible effects of awe and renewed vitality that come with spending time outdoors. One thing is certain though: time in green spaces really does have measurable effects on health. “Forest bathing” results in decreases in stress hormones as well as increased activity of natural killer cells and anti-cancer proteins. The beneficial effects resulted from visiting a forest but not a city. Interestingly the immune system boost lasted for over a week after the forest visit which suggests that daily exposure to green spaces might not be required to experience the benefit. This is promising for people whose work and family obligations may not leave them time for a leisurely stroll in the woods multiple times a week. Simply incorporating more time in nature on a regular basis could have significant positive effects. 

Bottom line: More time in nature is one “prescription” you can feel completely confident in recommending to your patients.