You don't have to be outside all day to reap nature's benefits


Dear Doctors: We’re all pretty stressed-out, even the kids. I keep saying that spending a Saturday in the nice park near our house could help, but my husband just laughs. Isn’t there some kind of research that being outdoors is good for you?

Dear Reader: Just thinking about a walk under the open sky as we began our answer to you brought about a sigh of relief. It makes sense, because long before we humans started spending so much time in built environments, we were deeply connected to the natural world. Many people have an innate understanding about that connection, and years of research backs them up.

Studies show that regularly spending time outdoors confers a host of mental health benefits. These include relief of anxiety and stress, a boost to feelings of calm, enjoyment and well-being, and improvements to mood and attitude. And that’s not taking into account the positive effect that even mild exercise, like walking, has on the body.

It seems like the link between time spent in nature and emotional well-being would be hard to prove, but researchers from the University of Michigan in Ann Arbor found a way. In fact, according to their study, published in 2019 in the journal Frontiers in Psychology, as little as 20 minutes spent outside in nature can have a healing effect. As an added surprise, their study showed the connection holds up even when the green space is in an urban environment.

Over the course of two months, the researchers had 36 volunteers spend at least 10 minutes three times per week in a variety of outdoor environments. These included public parks, the green spaces near their places of work or their own backyards. The participants could either sit still or stroll around during their outdoor time, but they were banned from chatting, reading or using screens of any kind. In order to rule out the known benefits of exercise, they were also asked to refrain from vigorous physical activity prior to their nature walks.

Elizabeth Ko, MD and Eve Glazier, MD

Before and after each outing, samples of saliva, which contains the stress hormone cortisol, were collected from each volunteer. Analysis of the saliva samples revealed that the volunteers returned from their nature outings with lower levels of cortisol than they started out with. Surprisingly, the biggest drops in the stress hormone occurred in the first 20 to 30 minutes of nature immersion. Benefits continued after that, but more gradually. Neither the time of day that someone chose to be outdoors nor where they spent their time played a role in the stress reduction. According to this study, the simple act of stepping outside into a green space began to bring relief.

The time frame that this study reveals is certainly new, but research about the benefits of spending time in nature dates back to the 1970s. We hope that, with proximity to a park and the low bar of 20 to 30 minutes, you’ll be able to persuade your family to make being outdoors a regular part of their lives.

(Send your questions to [email protected]. Owing to the volume of mail, personal replies cannot be provided.)