If you’re already in the habit of walking, sitting, hiking or running through forests or parks with an abundance of trees, you’ve probably noticed how nourishing the experience is: how spending time in the natural world, immersed in the energy of trees, rivers, mountains and wildflower-filled meadows — just feels really good. But why exactly is this? How does time away from city streets, in favor of more rural or back-country environments, actually affect our mental-emotional and physical health?

The Healing Benefits Of The Natural World

As it turns out, increasing numbers of scientific studies are verifying what so many of us have known, at more intuitive levels, for a long time: The natural world has profoundly healing effects on our bodies and minds. And reaping the benefits doesn’t even require us to be hardcore outdoor enthusiasts. Sure: backpacking, mountain-running, canoeing and biking are all great ways to increase our time communing with the natural world. But even just living near open green space has profound benefits.

“In 2009 a team of Dutch researchers found a lower incidence of 15 diseases, including depression, anxiety, heart disease, diabetes, asthma, and migraines, in people who lived within about a half mile of green space.”

Being in nature tends to make us calmer, kinder, physically healthier, more inspired and better able to problem-solve. So what’s happening, at a physiological level, that corresponds to such changes? According to David Strayer, a cognitive psychologist at the University of Utah who specializes in attention and is also an avid backpacker, the mental-emotional wellbeing we experience after spending time in nature results from a “cleaning of the mental windshield” or, speaking a bit more technically:

“being in nature allows the prefrontal cortex, the brain’s command center, to dial down and rest, like an overused muscle.”

Japanese researchers led by Yoshifumi Miyazaki discovered that a simple stroll through a forest led to a decrease in blood pressure, a drop in heart rate, and a significant decrease in the stress hormone cortisol: all physiological signs of deep relaxation. But why exactly do our human bodies respond in this fashion?

“15-minute walk in the woods causes measurable changes in physiology” Miyazaki believes our bodies relax in pleasant, natural surroundings because they evolved there. Our senses are adapted to interpret information about plants and streams, he says, “not traffic and high-rises.”

The Human Body-Mind’s Need For Full Spectrum Information

Ted Norretrander, author of The User Illusion, makes a similar point, in claiming that the “information age” is stressful not because there’s too much information, but rather because there’s too little. Most of our information (i.e. what we consciously process) here in the computer age — and more generally in the age of literacy — is focused within the very narrow bandwidth of written/spoken language, excluding all other varieties of sensation.

The situation we find ourselves in is a bit like sitting down for a meal, only to discover that the only course is dessert. While there’s nothing inherently wrong with dessert, a meal consisting also of an appetizer, soup, salad, steamed veggies, main dish and a cup of tea is much more nourishing and satisfying. If bits of information gleaned from books, phones and computers are, in this metaphor, akin to “dessert” then the information gleaned from the sights, sounds, smells and kinesthetic sensations of being in a forest, or in a mountain meadow, or canoeing down a river, are the soup, salad, steamed veggies and main dish. Our bodies and minds require a full spectrum of sensation/information in order to function properly.

Environmental psychologists Stephen and Rachel Kaplan (from the University of Michigan) have discovered the sights of the natural world to be particularly healing:

“the visual elements in natural environments, sunsets, streams, butterflies, that reduce stress and mental fatigue. Fascinating but not too demanding, such stimuli promote a gentle, soft focus that allows our brains to wander, rest, and recover from what Olmsted called the “nervous irritation” of city life.”

South Korea and Japan have long maintained officially designated Healing Forests, places to go to nourish and heal the body and mind. And “forest therapy,” in these countries, is frequently prescribed as part of the healing regimen for a wide variety of ailments, including recovery from alcoholism and PTSD. And now, forest therapy also has a North American branch.

If you’re a runner, already devoting several hours a week to training, then reaping the benefits of spending more time in the natural world can be as simple as shifting your routes to include more parks or forest trails. In this way, trees become your training partners. How wonderful!