I recently gave an author talk in Portsmouth, New Hampshire, about the mental health benefits of walking in nature. I shared some of the latest research about how time outdoors helps boost our moods and reduces symptoms of post-traumatic stress disorder, depression and anxiety. At the end of the talk, a woman raised her hand and said, “I go for walks, but I just can’t seem to stop thinking about my to-do list and all the things I have to deal with when the walk is over. What should I do?”
My answer was simple: “Go for longer.”
Thinking, thinking, thinking. We humans are lucky in that we can solve complex problems, remember important lessons from the past and plan for the future. We also have the capacity for self-reflection and the ability to change our habits. These superpowers—which reside in the most recently evolved part of our brain, the frontal cortex—helped us immeasurably in our struggle to survive, migrate, adapt to new environments and stay out of danger.
But a weird thing has happened to our frontal cortex as we’ve moved into urban environments and a life lived largely indoors: It works too hard. Often at our desks, multitasking on digital devices, checking items off our to-do lists or fretting that we are not getting enough done, we are taxing our brains like never before. Neuroscientists call this a top-down approach to life, because the cortex lies on top of older, more primal parts of the brain that we share with so many other creatures.
Solving problems and multitasking may sound productive, but ironically, too much time thinking and not enough time being, feeling and sensing can profoundly affect our happiness. Monks, poets and now neuroscientists and psychologists have figured this out. For example, as Stanford University psychologist James Gross and others have pointed out, rumination is linked to depression. The word rumination derives from what cows do— chew the cud, over and over, in order to digest it in their rumens. We don’t have rumens, but we sure know how to chew the metaphorical cud way too long.
Too much time thinking and not enough time being, feeling and sensing can profoundly affect our happiness.
In psych-speak, rumination essentially translates to brooding: playing back in a loop negative memories, worries or feelings of low self-worth. Wanting to test how different environments influenced our negative thinking, Gross and colleagues at Stanford designed a study in which participants walked for 50 minutes in either a grassy and wooded natural area or along a busy street in Palo Alto, California. They found that only after the nature walk, not the city one, the walkers scored lower (in other words, better) on a questionnaire measuring rumination. One example: “I often reflect on episodes of my life that I should no longer concern myself with.” The nature walkers also reported feeling happier.
The researchers speculated this might be because outside on the nature trail, walkers found pleasant features to look at and engage with. “Nature experience may decrease rumination in participants due to an increased focus on aspects of the environment that are not directly related to narratives about the self,” they wrote. In other words, nature and its beauties distracted the walkers in a good way, drawing them out of themselves.
The researchers were curious whether they could see these changes in thinking and mood in blood flow patterns in the brain. (More blood flow generally indicates parts of the brain that are firing up and working hard.) So, they designed another study. In this one, they assigned healthy adults to walk—this time for 90 minutes—in either the nature area or along the busy, urban street. They administered the same questionnaires, but this time they scanned the walkers’ brains before and after the walk using a method called arterial spin labeling. Once again, the nature walkers reported feeling happier than the urban walkers after the 90 minutes outside, and their brains also showed reduced activity, or less blood flow, in a part of the brain called the subgenual prefrontal cortex. This neuronal real estate has been linked to rumination and depression. Notably, the urban walkers’ brains did not show this change. Nature has a unique way of telling us: Quit focusing on yourself. There’s a whole beautiful world out there.
To those of us who routinely spend time on trails, rivers and ski runs, these results probably come as no surprise. We know we leave cares behind, feel lighter and brighter after being outside for a while. But we may not be thinking of nature as a tool for preventing depression and other mental health conditions. Liisa Tyrväinen, who runs a research division of the National Resources Institute of Finland, told me she is so convinced of these benefits that she issues a specific recommendation to urbanites designed to prevent mild depression: a minimum dose of five hours a month in the woods. This translates to about two 40-minute walks per week. But some of us may need a bit longer than that to get out of the thinking-tasking-worrying loop our brains are so used to, especially if our ailments are more severe.
We leave cares behind, feel lighter and brighter after being outside for a while.
Annette McGivney, a writer who suffers from PTSD and has authored a new book, “Pure Land: A True Story of Three Lives, Three Cultures, and the Search for Heaven on Earth,” tries to walk several hours per week outside. As she puts it, “I realized that the only place where I could get my thoughts to stop was in the wild.” To my recommendation of going outside for longer, she adds two of her own: Turn off your phone and focus on engaging your senses, such as breathing in the smell of the trees.
McGivney follows a long line of writers, philosophers and Romantics who found they could shed their cares—at least for a time—by heading outdoors. Like so many, Frederick Law Olmsted, the famous 19th-century landscape architect, intuitively understood the neuroscience behind feeling well in beautiful places: “Viewing nature,” he wrote in 1865, “employs the mind without fatigue and yet exercises it; tranquilizes it and yet enlivens it.”
Tranquility plus enlivening: This is certainly a space—along with being on a wild trail—where our brains love to be.