(Flickr / Luke Redmond)
If living in a big city has you feeling a bit down, there's good news: A brief walk in nature could be all it takes to chase away those negative thoughts.
At least that's the finding of a new study published Monday, June 29, in the Proceedings of the National Academy of Sciences.
In the study, a group of 38 Northern Californians (18 women and 20 men) were split up into two groups — one who took a 90-minute walk in nature and another that did the same walk in the city. The nature walkers reported having fewer negative thoughts about themselves after the walk than before the walk, while the urban walkers reported no change.
What's more, fMRI brain scans revealed less activity in the subgenual prefrontal cortex (sgPFC), a brain region that may play a key role in some mood disorders and has been linked with patterns of negative thought, according to the study. Those who went on the urban walk did not show any of these benefits, the study found.
Today, more than half of the world's population lives in urban areas, and at the present rate, 70% of people will live in cities by 2050.
"What are the ramifications that happen when we move away from regular contact with nature?" study researcher Gregory Bratman, an environmental psychologist at Stanford University, said in an interview with Business Insider.
Despite the benefits of city life, urban populations tend to have higher rates of mental illness, especially anxiety and depression. Several other studies have also suggested that there's just something about being in nature that can give our moods a boost. But it hasn't been clear exactly what's going on in our brains when we're exposed to natural environments.
One possibility is that nature decreases "rumination," or patterns of negative thoughts that swirl in our heads and seem to take over. Increased rumination has been linked to a higher risk for depression and other mental illnesses.
(star5112/Flickr Creative Commons)
To find out if nature helps us end that cycle of negative thoughts, Bratman and his colleagues randomly assigned his 38 volunteers to take a 90-minute walk in either a natural or an urban area.
The nature walk took place in a grassland with oak trees and shrubs near Stanford University, an academic, highly suburban community of some 30,000 people. The urban walk went along a highly trafficked, multi-lane street in Palo Alto, a city that's roughly twice the size of Stanford. The volunteers were each given a smartphone and told to take 10 photos during their walk (the phones were also used to track their location and ensure they followed the assigned route).
Before and after the walk, the participants filled out a questionnaire about how much they were ruminating, and had their brains scanned using a form of magnetic resonance imaging that measures blood flow in the brain at rest.
At last, we may have a possible explanation for how being in nature may improve our mental well-being. In addition, the findings suggest that having green spaces and natural areas in cities may be critical for maintaining our mental health.
Andreas Meyer-Lindenberg, director of the Central Institute of Mental Health in Mannheim, Germany, has also studied the effects of urban life on mental health. He told Business Insider that the new findings agree with his own research. He also said the new research offers added evidence that being exposed to nature helps us regulate our emotions and may help to protect us from depression.
Of course, the study was relatively small, and Meyer-Lindenberg said he'd like to see if the findings hold if people are exposed to natural or urban environments for a longer period of time.
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