Spending time in nature can boost overall well-being, but how much exposure do we need? A new study concludes that 2 hours each week is enough to reap the benefits, though significant questions remain.

In Western society, as overall interaction with nature slowly declines, scientists are exploring whether reconnecting with parks, woodlands, and beaches might benefit our general health and well-being.

Researchers have run a number of studies, of varying quality, that have examined the role of human interaction with nature in overall health.

For instance, one study concluded that living in areas with more trees increases a person's perception of both physical and mental health and reduces the risk of cardiometabolic conditions.

One 2016 review concluded that "living in areas with higher amounts of green spaces reduces mortality, mainly [cardiovascular disease]."

Despite the slow accumulation of evidence for the benefits of visiting green spaces, no one has calculated the exact amount of time someone needs to spend in nature to reap the benefits.

The authors of the new study, from the University of Exeter Medical School in the United Kingdom and Uppsala University in Sweden, aimed to "better understand the relationships between time spent in nature per week and self-reported health and subjective well-being."

They recently published their findings in the journal Scientific Reports.

Timing interactions with nature

To investigate, the team took data from the Monitor of Engagement with the Natural Environment survey, which includes a representative sample of the U.K. public. The researchers collected data for this survey by conducting face-to-face interviews at participants' homes.

They used a sample of 20,264 people and asked them a range of questions, two of which were, "How is your health in general?" and "Overall, how satisfied are you with life nowadays?"

They also asked the participants how much contact they had had with nature in the past 7 days, including "parks, canals, and nature areas; the coast and beaches; and the countryside including farmland, woodland, hills, and rivers," but not including "routine shopping trips or time spent in your own garden."

The researchers asked how often they went and how long each visit lasted; from that information, they extrapolated the participants' average weekly exposure to nature.

Before analysis, the scientists also controlled for a long list of variables, including sex, age, the average amount of exercise taken each week, the level of deprivation in the local area, dog ownership, and relationship status.

2 hours each week

They found that there were no significant benefits to self-reported health or well-being until participants reached the 2-hour mark. Any less did not make a noticeable difference, and any more did not boost the positive effect any further.

People could take the 2-hour exposure as one long trip or across several shorter trips.

"Two hours a week is hopefully a realistic target for many people, especially given that it can be spread over an entire week to get the benefit." Study lead Dr. Mathew P. White

The study authors discuss the size of the positive effect, explaining that the increase in self-reported health and well-being following 2 hours of contact with nature each week is similar to the differences observed in:

• people living in an area of low versus high deprivation
• people employed in a high versus low social grade occupation
• people who achieve the recommended levels of physical activity in the previous week versus those who do not

Because of the impressive size of the effect, the team hopes that public health officials will soon be able to use the growing body of evidence to inform new policies. As study co-author Prof. Terry Hartig explains:

"There are many reasons why spending time in nature may be good for health and well-being, including getting perspective on life circumstances, reducing stress, and enjoying quality time with friends and family."

He adds, "The current findings offer valuable support to health practitioners in making recommendations about spending time in nature to promote basic health and well-being, similar to guidelines for weekly physical [activity]."

A number of limitations

This study encounters the issue of cause and effect; for instance, perhaps people who experience depressive symptoms do not feel the urge to visit forests.

As its authors write, "we are unable to rule out the possibility that the association is, at least in part, due to healthier, happier people spending more time in nature."

They also explain that their method for measuring weekly exposure to nature was far from perfect, writing that they "asked about only a single randomly selected visit in the [p]ast week." However, they believe that across more than 20,000 people, this effect should cancel out.

Also, they reiterate how important it is to treat interview data "with caution," as human memory is certainly not perfect.

Although the 2-hour threshold is the headline statistic, the authors call for caution here, too. They believe that, at least in part, this duration could be due to clustering in the data; people are much more likely to say that they visited a forest for 1 or 2 hours, for instance, rather than 1 hour and 23 minutes or 2 hours and 49 minutes.

Limitations aside, the evidence is mounting for the psychological benefits of spending time in nature.

Source:Medicalnewstoday.com