Nature restores mental functioning in the same way that food and water restore bodies. The business of everyday life -- dodging traffic, making decisions and judgment calls, interacting with strangers -- is depleting, and what man-made environments take away from us, nature gives back. There's something mystical and, you might say, unscientific about this claim, but its heart actually rests in what psychologists call attention restoration theory, or ART. According to ART, urban environments are draining because they force us to direct our attention to specific tasks (e.g., avoiding the onslaught of traffic) and grab our attention dynamically, compelling us to "look here!" before telling us to instead "look over there!" These demands are draining -- and they're also absent in natural environments. Forests, streams, rivers, lakes, and oceans demand very little from us, though they're still engaging, ever changing, and attention-grabbing. The difference between natural and urban landscapes is how they command our attention. While man-made landscapes bombard us with stimulation, their natural counterparts give us the chance to think as much or as little as we'd like, and the opportunity to replenish exhausted mental resources.

Healers in Japan and Germany have long heralded the benefits of natural therapy, recognizing that humankind has spent 99.99 percent of its history living in natural environments. The Japanese version of natural therapy is shinrin-yoku, or forest bathing, which requires that patients walk for extended periods through forested areas while inhaling woodsy scents that complement the sylvan atmosphere. German Kneipp therapy similarly requires that patients perform physical exercises in forest clearings. These alternative therapies aren't just idle cultural quirks, and researchers have found that patients enjoy a wide range of benefits. Among others, compared with people who walked through urban areas, shinrin-yoku patients had lower blood pressure, lower pulse rates, and lower cortisol levels, a marker of reduced stress. People who are exposed to natural scenes aren't just happier or more comfortable; the very building blocks of their physiological well-being also respond positively to natural therapy.

Natural environments promote calmness and well-being in part because they expose people to low levels of stress. These stressful experiences are tame in comparison with the trials and tribulations that most of us associate with stress -- workplace drama, traffic jams, and wailing children on international plane trips. Humans thrive with some stimulation, but we're incapable of coping with extreme stressors, which push us from the comfortable realm of eustress (good stress) to the danger zone of distress (bad stress).

Interesting locations, including busy natural environments, are so beneficial that physicians have begun to suggest that they might offer a cheap and effective way to lessen the effects of certain cancers. One team of researchers showed that women who were recently diagnosed with early-stage breast cancer were far more capable of completing challenging mental tasks when they immersed themselves in natural environments for two hours each week for approximately two months. The interventions began when the women were diagnosed, and continued beyond surgery into the recovery period. Like many distressed patients who begin to battle life-threatening illnesses, the women struggled to complete difficult mental tasks shortly after they were diagnosed. Those who spent time in natural environments improved progressively, regaining their capacity to devote attention to demanding mental puzzles. Meanwhile, the patients who were not exposed to the nature-based intervention tended to struggle with similar tasks throughout the test period.

Attention is obviously a long way from recovery, but patients with sharper minds often respond better to treatment, stick to their treatment regimens, and behave more proactively during recovery. Of course, nature is not a panacea, but it's an inexpensive and effective tool for dampening the impact of illness, and dulling the intrusion of everyday stress.

This is an excerpt from Drunk Tank Pink: And Other Unexpected Forces That Shape How We Think, Feel, and Behave.