As with much health advice, the simplest prescriptions seem to be the most effective. Common sense reigns supreme. That's the consensus of a new study, published in Scientific Reports on June 13, which offers the most basic guidelines imaginable: spending at least two hours a week in nature will do wonders for your health.

The researchers, based at the U.K.'s Exeter Medical School, scoured previous studies to better understand how simply being outside benefits us. What did they find? They discovered being immersed in nature lower probabilities of asthma hospitalization, cardiovascular disease, diabetes, mental distress, obesity, and mortality in adults; it has also been shown to reduce obesity and myopia in children.

Two hours weekly appears to be the sweet spot, with peak positive associations capping between 200–300 minutes. One caveat: the research is based on nearly 20,000 people that live in dense urban regions. This makes sense, as it is this population most in need of woods, lakes, and mountains. There's only so much one can take staring at asphalt (or a screen).

That being in nature bestows health benefits shouldn't be surprising; it is where humans spent most of their time until quite recently. Many other prescriptions, from Japanese forest bathing to Swedish plogging (cleaning up trash in natural environments) have been touted as being mentally and physically positive activities. It seems the further disconnected from nature we become, the more we crave it.

It doesn't matter how you break up the weekly 120 minutes. A daily walk or a once-weekly hike both do the trick. The researchers also don't differentiate between environments. A local park appears to be as effective as an oceanside hike or heading deep into the forest.

Prescribing Nature for Health | Nooshin Razani | TEDxNashville

Such information is especially important considering that 68 percent of the world's population is expected to live in urban areas in the next three decades. Social animals by nature, the allure of cities is pulling residents to congregate in tighter proximity. The trade-off is further disconnection from the land that first gave birth to our species.

Of course, escape is always possible. Motivation and time management are key factors. Consider the varied possibilities for those living in New York City. You can always jump on a train in any direction: east to the Rockaways and Long Island, north to New York State's incredible hiking, west to the Delaware Water Gap, south to plenty of green space in Jersey. Making it part of your week is the real challenge for Manhattanites that rarely leave their borough.

On the other side of the nation, nature is everywhere in Los Angeles. Ironically, the metropolis boasts the fewest public parks in the world for a city of this size. Again, time management and motivation: getting to the mountains is possible from most parts of the city within 20 minutes. The benefits are worth it. Being proactive about your health is the challenge.

Interestingly, the study draws the line at 120 minutes. Participants that logged between one and 119 minutes reported no better subjective well-being than those who spent no time in nature. The threshold appears to be 120 minutes, with benefits lasting up to 300 minutes. At that point, no further benefits accrue.

Medical professionals are also recognizing this trend. In Scotland, doctors are authorized to prescribe nature walks to their patients. As far back as the '70s doctors realized that hospital patients with more natural light in their rooms healed quicker than those facing buildings or other obstructions.

City governments realize that urban regions need to include plenty of green space. The Brooklyn waterfront is being transformed from ports of industry to parks of leisure. In 2008, Portland, Oregon, launched its Grey to Green initiative to reimagine its entire infrastructure. Even as Copenhagen is becoming a tech leader, the nine artificial islands under construction of the city's coast includes plenty of green space.

While cities and doctors are playing a role in bringing us closer to nature, it's still up to us city dwellers to put in the effort. Personal history, biodiversity, and even ethnicity are involved in the study above. As the team writes,

"Research considering the quality of the natural environment in terms of plant and/or animal species richness suggests that experiences may be better in more biodiverse settings. Contact with nature is more than just a complex multi-sensory experience, to varying degrees personal histories and meanings, longstanding cultural practices, and a sense of place play some role in the benefits realized, factors which may account for why we did not find the same pattern for health individuals not identifying as White British."

Even weighing in these factors, the message is clear: get outdoors. We were born of this earth. The less time we spend locked away from it, the more likely we are to experience negative mental and physical health. Fortunately, the opposite is also true. We just have to step outside.

--

Stay in touch with Derek on Twitter and Facebook.