How long does it take to get a dose of nature high enough to make people say they feel healthy and have a strong sense of well-being? Precisely 120 minutes.
In a study of 20,000 people, a team led by Mathew White of the European Centre for Environment & Human Health at the University of Exeter, found that people who spent two hours a week in green spaces — local parks or other natural environments, either all at once or spaced over several visits — were substantially more likely to report good health and psychological well-being than those who don’t. Two hours was a hard boundary: The study, published last June, showed there were no benefits for people who didn’t meet that threshold.
The effects were robust, cutting across different occupations, ethnic groups, people from rich and poor areas, and people with chronic illnesses and disabilities.
The study by White and his colleagues is only the latest in a rapidly expanding area of research that finds nature has robust effects on people’s health — physically, mentally, and emotionally.
These studies have shown that time in nature — as long as people feel safe — is an antidote for stress: It can lower blood pressure and stress hormone levels, reduce nervous system arousal, enhance immune system function, increase self-esteem, reduce anxiety, and improve mood. Attention Deficit Disorder and aggression lessen in natural environments, which also help speed the rate of healing. In a recent study, psychiatric unit researchers found that being in nature reduced feelings of isolation, promoted calm, and lifted mood among patients.
The growing body of research — combined with an intuitive understanding that nature is vital and increased concerns about the exploding use of smart phones and other forms of technology — has led to tipping point at which health experts, researchers, and government officials are now proposing widespread changes aimed at bringing nature into people’s everyday lives.
For example, researchers and policymakers now talk about “park deserts” in urban areas. Cities are adding or enhancing parks, and schools and other institutions are being designed with large windows and access to trees and green space — or blue space, as in aquatic environments. Businesses are increasingly aware of the desire among employees for access to green spaces.
The number of “forest schools” — which have long been a tradition in Scandinavia and where much of the learning takes place in natural settings in the outdoors — has mushroomed in the United States, up by 500 percent since 2012, according to Louv. Oregon recently passed a ballot measure to raise money for outdoor schools, and the state of Washington just became the first state to license outdoor preschools, where much of the play and learning occurs outside.
What are the active ingredients in a dose of nature?
Pioneers in this work, Rachel and Stephen Kaplan, who began studying the subject in the 1970s, devised Attention Restoration Theory, which holds that paying attention in bustling cities, at work, or in other stressful environments requires a good deal of effortful attention. In a natural environment, however, the Kaplans found that people paid attention more broadly and in a less effortful way, which leads to far more relaxed body and mind.
Japanese researchers have studied “forest bathing” — a poetic name for walking in the woods. They suspect aerosols from the forests, inhaled during a walk, are behind elevated levels of Natural Killer or NK cells in the immune system, which fight tumors and infections. A subsequent study, in which essential oils from cedars were emitted in a hotel room where people slept, also caused a significant spike in NK cells.
Understanding nature’s therapeutic effects may be arriving at a propitious moment. Some studies have found that anxiety over climate change is a growing phenomenon. Ironically, one of the best antidotes for that might be a dose of green space.
Article adapted from Yale.edu.