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As the weather warms up across Sonoma County, it’s a safe bet many wish they were spending the day out in nature, walking through a green shady grove, a color-filled meadow or along the beach, lulled by the pulsing surf.

What if such experiences weren’t just enjoyable, but could actually improve our physical and mental health? A growing number of new studies are finding they do. Exposure to nature, it turns out, affects us in surprising ways, right down to our cells.

Howard Frumkin is an physician with an impressive background in environmental medicine and a precise, direct manner. After years at the Centers for Disease Control and Prevention, he’s now dean of Environmental and Occupational Health Sciences at the University of Washington, and an international authority on the link between nature and public health.

He recently released a review of scores of scientific studies that show being active in nature can protect against chronic diseases and aging, relieve stress and depression, improve pain control, promote faster healing and stronger immune systems, boost memory, longer life and more. And it’s effective at any age, from childhood to well beyond retirement.

“We’re in the early days of building the evidence base, but we already know enough to act,” Frumkin said.

That evidence dates back to 1984, when one of the first clinical studies found that surgical patients who had a view of trees out their hospital window recovered differently than those with a window facing a brick wall. The patients with the leafy view healed a day faster, needed significantly less pain medication and had fewer complications.

Newer studies have confirmed those results, and found that even images of nature can produce measurable medical benefits in hospitalized patients. That’s one reason modern hospitals are now designed with plenty of greenery and natural settings.

Such effects aren’t entirely surprising, considering humans evolved out under the sun.

We still need direct sunlight on our skin today to produce essential vitamin D. The UV light that makes it can’t pass through glass, which is the reason we rely on vitamin D supplements in milk for children and pills for adults, and Vitamin D deficiency is now officially designated a global health pandemic by the World Health Organization. We’ve largely drifted out of touch with nature, individually and as a species.

And it’s been a sudden, very recent shift. Our anatomically human ancestors lived entirely embedded in nature, hunting and gathering for roughly 1.8 million years. According to archaeologists, for 200,000 years fully modern humans like ourselves were still living off the landscape in something like full-time camping. We didn’t start farming until 10,000 or so years ago, which means, for more than 99.5 percent of human existence, we were intimately connected, and exposed to, the natural world.

As a result, nearly everything about us — how our organs work, our eyes, minds, immune system, musculature, and chemistry — has been finely tuned for survival out in the wild crucible of nature.

As recently as the 1880s, nearly everyone, an estimated 97 percent of all humanity, was still living in direct contact with nature, in rural or natural settings. But little more than 100 years later — by 2008 — half of all people on the planet had made the move to dwellings in cities and urban environments.

From a biological perspective, this shift marks a sudden and deep disconnection from the natural environment we were designed to flourish in.

In America, a recent poll by the Nature Conservancy found only 10 percent of teens spend daily time outside, and their parents aren’t much better. According to the Harvard School of Public Health, adults in the US spend less than 5 percent of their day outdoors, much less than they spend inside their cars.

Nature deficit?

Santa Rosa pediatrician Ari Hauptman, a Board Member of the Sonoma County Regional Parks Foundation, believes there’s ample evidence physicians should be prescribing active time in nature to their patients. He notes that a growing body of researchers, health professionals and naturalists have begun to seriously question whether a so-called “nature deficit” is having a serious physical impact on our health and wellbeing.

His concerns are supported by science. Studies in China have found steadily increasing rates of myopia, or nearsightedness, among children as a direct consequence of spending less time playing outdoors.

Dr. Deborah Cohen, a researcher at the RAND Corp., wondered whether mental health and psychological stress is affected by the amount of time people spend outdoors. After excluding other factors, her studies across Los Angeles found that people’s mental health scores declined the farther they lived from parks. The highest mental health rankings were held by residents who lived a short walk from urban parks, and they fell steadily with increasing distance. Perhaps not surprisingly, the people who lived closest to the parks spent more time in them.

A recent Australian and UK study similarly found that people who visited parks for 30 minutes or more each week were much less likely to have high blood pressure or poor mental health than those who didn’t.

Does being physically active in nature beat exercise indoors? Frumkin cites 11 separate studies that looked to see if there was any difference. The tests all showed that adults who exercised in nature had lower levels of tension, anger and depression than when they exercised the same amount indoors.

Other studies with soldiers suffering from PTSD have found that physical exertion in outdoor activities significantly reduced their symptoms, results that were not found when they exercised indoors.

Freeing the brain

The reasons aren’t entirely clear. They may be partly psychological, and some suggest they’re tied to our evolutionary needs. But the responses may actually have to do with what’s going on in our brains. Scientists now have tools that allow them to peer in on brain activity and see what happens when we’re exposed to nature.

In one study, scientists monitored participants’ brains as they viewed either nature scenes or urban scenes. The scenes of nature lit up regions of the brain linked to happiness, insight and free-thinking. But urban images stimulated the amygdala and other regions associated with stress, fear and anxiety.

A recent Stanford study measured activity in the brains of volunteers who either walked for 90 minutes in grasslands with oak trees, or along a busy four-lane roadway. No change was observed in the urban walkers, but the nature walkers had suppressed activity in a region associated with rumination, the repeated review of negative experiences, which is associated with depression.

International studies have regularly documented that activity in nature relieves anxiety and stress, and even reduces blood levels of stress hormones, like cortisol.

Children and adults who spend more time outdoors also tend to be less sedentary and more physically active. And moderate physical activity is known to generate a very wide range of health benefits, from protection against diabetes and reducing the risk of cancers to improving memory.

Until recently, science has not understood why.

Researchers have made the surprising discovery that during moderate and prolonged exercise, contracting skeletal muscles, the muscles which are attached to bones, release a variety of signal proteins called myokines. In the body, these myokines have a range of effects on organs and biological systems, from reducing inflammation, to ramping up the immune system, to suppressing appetite. While myokine studies are in early stages, it’s clear that when activated, our muscles are sophisticated organs that chemically influence other bodily processes.

The ‘green gym’

Frumkin, Cohen, Hauptman and other experts increasingly believe that based on the accumulated evidence of actual health benefits, we are not doing nearly enough to encourage people to spend time outdoors, or invest in parks and nature programs.

Fortunately, as Hauptman says, Sonoma County provides rich and varied opportunities to get out and explore nature, experience amazement and awe, reduce stress, and enjoy the documented benefits of being physically active in what experts are calling the “green gym.”

Compared with all other modern medical interventions and pharmaceuticals, these medical experts note, a prescription to spend time in nature is low cost, widely available and a highly effective way of achieving a broad range of health outcomes with minimal side effects.

Stephen Nett is a Bodega Bay-based Certified California Naturalist, writer and speaker. Contact him at snett@californiasparks.com.

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