Leafy Calm

Henry David Thoreau famously fled to a small cabin on Massachusetts’ Walden Pond to recoup his mental faculties. The American writer, it seems, didn’t just inspire generations of poets both good and bad. He also may have stumbled across a prescription for better health. A new study shows that even brief encounters with parks or forests may have beneficial impacts on human hormone cycles, critical to the body’s response to stress.

The benefits of fresh air and a brisk hike–call it the Thoreau effect–are well known to scientists. In a previous study, for instance, Japanese researchers explored the relationship simply by taking a few urbanites on a walk through a forest. After this Shinrin-yoku, or “forest bathing,” the participants’ blood pressures dropped noticeably.

But Catharine Ward Thompson of the University of Edinburgh and colleagues wanted to test how routine, or even chance, brush-ups with greenery might affect the body. To do that, they tracked 35 unemployed people between the ages of 35-55 living in Dundee, just north of Scotland’s capital in the United Kingdom. Specifically, the team monitored daily fluctuations in the Scots’ cortisol levels. This hormone, involved in the stress response, typically peaks in the blood after waking and drops to near zero during sleep.

Forget the apple-a-day rule, the authors found. Proximity to green areas, from forest preserves to walking trails and city parks, seemed to be a recipe for better well-being, Thompson and colleagues report in Landscape and Urban Planning. The subjects that lived closer to greenery claimed to be less anxious than their counterparts trapped in the city, according to surveys. And their stress hormones, measured in saliva, also cycled more uniformly. Such ebbs and flow appear to signal good mental health, the team says. In contrast, individuals diagnosed with clinical depression or post-traumatic stress disorder display flattened out levels of cortisol.

One reason green may be a balm, the authors conclude, is that people often meet up with friends in green areas–a sure-fire cure for nerves. Or, like Thoreau, they may just feel more at home with their toes in the grass. Either way, it’s a good lesson for city planners. Daniel Strain | February 5, 2012

Source: Thompson CW, et al. (2012) More green space is linked to less stress in deprived communities: Evidence from salivary cortisol patterns. Landscape and Urban Planning. http://www.citeulike.org/article/10282677. DOI:10.1016/j.landurbplan.2011.12.015

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