Just heading out the door to take a walk can calm the mind. If you hop in the car and head down to the park to take your walk, or if you have a nature preserve or a lake near you, that walk in nature can calm the mind and even alter the way that the brain works so that your mental health improves as a result, according to the results of a new study of how taking time to walk in nature physically impacts the brain.
Most people today live in urban settings, and even people living in smaller towns spend a lot less time outside in nature than people did even a decade or two ago, and especially in comparison to a generation or two ago. Individuals who live in cities are at greater risk of summering from depression, anxiety and other mental disorders than people living outside major urban areas.
More and more research is showing that there are connections between the amount of time that people spend in nature and their overall mental health. In these studies, researchers have concluded that the less access you have to green, natural spaces, the higher your risk is of developing psychological problems. However, even if you live in a city, if you take the time to visit parks or other natural spaces, your stress hormone levels drop almost immediately after you leave.
But how does this actually work? This question motivated Gregory Bratman, a graduate research student at Stanford University’s Emmett Interdisciplinary Program in Environment and Resources, as he was studying the psychological impact of living in the city. He published a study in July 2015, indicating that volunteers who took a short walk through a green, vibrant part of the university at Stanford were happier and paid better attention than students who marched during an identical time frame near a street crowded with traffic.
Next, Bratman pursued a second study in which the researchers looked at how a walk through nature could influence a person’s likelihood of brooding. In the field of mental health, “brooding” is a technical term also known as morbid rumination. In lay terms, this means a time when you sit and think about the things that aren’t going well in your life. You have a hard time breaking out of this loop, which keeps going over and over in your mind. It can lead to an unhealthy cycle and can be a step on the path to depression. Previous studies have shown that this is a condition that strikes city dwellers much more frequently than those who live in less densely populated areas.
One process that Bratman’s study dealt with was activity in the subgenual prefrontal cortex, which elevates during periods of brooding. Bratman sought to track activity in that area of the brain before and after participants went through nature. Understanding how that experience affects brain activity would indicate how interacting with nature influences the mind.
In this second study, Bratman brought in 38 urban residents, all healthy adults, and gave them questionnaires about the time they typically spent brooding. They also underwent scans to check the activity in their subgenual prefrontal cortex (indicated by blood flow). The more blood flow, the greater the activity. The group of participants was randomly divided in half. All participants took a 90-minute walk, but half of them walked through a part of the Stanford campus that resembled a park in its quiet calm and dense tree growth, and the other half walked next to a highway in Palo Alto that was busy and loud. The participants had to walk alone and could not listen to any music. Right after the walk was finished, the participants took the questionnaire and the brain scan once again.
Those who had walked next to the highway did not show any change in the blood flow to their subgenual prefrontal cortex and in their scores for brooding. Those who had gone through the campus showed a decrease in their brooding levels on the questionnaire, and the brain scan revealed that blood flow to the subgenual prefrontal cortex had dropped.
Obviously, there are still factors that need more study, such as how much time one should spend in nature to experience this calm, or what elements in nature soothe people the most (trees, quiet, sunshine, pleasant odors, proximity to water, and the like), or how much physical activity and nature go hand in hand. However, the signs are clear — if you take a walk outside in a park, you’re likely to feel better, not just because you got in some exercise but also because you were leaving the world of pavement behind and enjoying the green sights.