Many of us who’ve taken our running routines from the treadmill to the streets or trails get a sense that being outdoors makes us feel better, even if that sense is hard to explain or put into words. 

Luckily, that’s where science comes in. A growing number of studies show that spending time in nature provides myriad mental and physical health benefits. From eco-therapies to mainstream medical prescriptions or our fundamental evolutionary needs, it’s become clear that going outside is tied to our well-being in very positive ways. 

Better mental health and well-being

Natural scenery has long been a fringe tool in mental health therapies. But in the last few years it’s gained more momentum and mainstream recognition for its positive impacts. This is in part thanks to the popularity of Shinrin Yoku, or “forest bathing”, an eco-therapy developed in Japan in the 1980s that’s spread to other parts of the world. 

So why is nature a tool for improved mental health? It’s actually pretty simple: Several studies have shown that spending time in natural environments reduces the stress hormone cortisol.

Overexposure to cortisol and other stress hormones, like adrenaline, can increase the risk of mental health issues like anxiety, depression, and memory and concentration impairment; and lead to heart disease, weight gain and high blood pressure, among other health problems. 

Concentrated time spent outside, on the other hand, is linked to improved sleep quality, mood and cognition; lower blood pressure; and relief in depressive tendencies and a range of other stress-related issues.  

Up until recently though, it was unclear just how much time outdoors was needed to feel these benefits. A 2019 study finally answered that question: after just 20 minutes per day spent in nature, or two hours per week, people reported better health and a greater sense of well-being than those who didn’t go outside. 

Several studies suggest spending time outdoors provides an added sense of well-being – specifically for women. According to one study, time in nature serves as an escape from pressures unique to women in everyday life (i.e., conforming to expectations about weight, appearance, demeanor, etc., and putting in longer hours on the job, childcare and housework), which in turn boosts self-esteem and happiness, lowers stress levels, and positively effects both mental and physical health. Studies also show that women need a longer exposure time to nature to see a measurable stress reduction. That’s why, explains Dr. Nooshin Razani, who runs the Center for Nature and Health at UCSF, women shouldn’t feel that taking the time for “self-care” outside is an indulgent or extra thing to do, but rather something everyone deserves as a critical component of overall health. 

Regardless of gender, Dr. Razani says the results of these studies listing the benefits to our well-being of spending time outside are unsurprising. “What we should be asking at this point is: what’s the impact of not being in nature?” she says. 

“We evolved to be outdoors, after all. Now we likely spend the whole day inside. That’s why there’s now a national movement of doctors talking about time in nature the way we talk about reducing tobacco or alcohol use: as a way to promote healthy active living.”

Better physical health

As well as the compelling benefits to mental health, researchers are also increasingly  finding links between time outdoors and better physical health outcomes. These include decreases in incidences of diabetes and cardio-vascular mortality, lower blood pressure and heart rate, and better immune system function. As a result, more and more doctors are part of the rapidly growing movement of “nature prescription” programs that literally prescribe nature’s innate health benefits.

So, what does a nature prescription look like? Of course, that depends that varies on the patient and condition, but it might mean that a doctor prescribes going outside three times a week for half an hour per session with a follow-up to monitor results. Nature prescriptions are increasingly gaining traction as legitimate medical treatments for a range of conditions from heart disease, hypertension, high cholesterol and diabetes, to chronic stress, depression and anxiety, insomnia, and even PTSD.

Because prescriptions are paired with referrals to green spaces, this movement has created a series of interlocking partnerships between physicians, public lands agencies and nonprofits to get countless patients outside in locally accessed nature for better health – like the national Park Rx initiative in the US, which has grown to over 100 programs nationwide. 

Park Rx began over a decade ago with a group of physicians, health care providers and the Golden Gate Park examining how to get health care practitioners to prescribe time outdoors in the same way they prescribe drugs. The model has been so successful that it’s beginning to legitimize the prescriptions for use in mainstream medicine, says Diane Mailey, director at the Golden Gate National Parks Conservancy that helps run Parks Rx and works at the intersection of parks and social good to make parks – and their health benefits – accessible for all. 

Nature prescriptions and their supporting studies have amassed so much evidence of nature’s link to a healthier lifestyle that “major health insurance programs like Blue Cross Blue Shield are actually incentivizing doctors for nature prescriptions as part of a healthier lifestyle to lower the cost of health care,” she says.

Feeding our biophilia

Dr. Keith Tidball, an author and researcher at Cornell University, believes that a major reason spending time outside makes us feel better is that a connection to nature fulfils a deep evolutionary need.

He’s talking about biophilia, a concept explained as “the love of all that’s alive” or an “affinity to connect with living systems and living organisms.” Many researchers believe that this evolutionary affinity is the foundation for why forest bathing and nature prescriptions have such a positive impact on mind and body. 

“It’s a baseline for all humans that at some level we want to affiliate with all life, a way of thinking about our baked-in evolutionary need to affiliate with the rest of nature where we spent thousands and thousands of years,” Tidball says. 

“It’s only in the last couple hundred years that we’ve become separate from nature. But we’re compelled to affiliate with nature because we associate it with the healing aspects of hope and optimism.”

Dr. Razani and her colleagues feel it’s important that everyone has access to parks and other natural spaces for these reasons. “The right to be outdoors and to recreate and exercise in nature is a right for all, one that we should be advocating for.”

For those of us who can’t make it to a park or other natural space easily, she points to alternatives like a walk down an urban street or even looking up at the sky. These can offer mental and physical benefits too – in fact, one study showed that even looking out of a window at trees can lower stress levels.

Which leads to one more piece of good news: spending time in nature to soak up these health benefits doesn’t have to cost much. It’s as cheap as heading out the door. So lace up your shoes and get out when you can, where you can and where you feel comfortable. Better well-being awaits.