02/26/2014 05:00 EST | Updated 04/27/2014 05:59 EDT

Kids need to offset 'screen time' with 'nature time'

While experts worry about the ills of the internet age and the health problems linked to kids' hours of screen time, Richard Louv says there is an antidote - and it's free.

Louv is the author of Last Child in the Woods and The Nature Principle, and he coined the term "nature deficit disorder." He says spending time in nature has a wide range of benefits for physical and mental health.

"The symptoms of attention deficit disorder go down in kids as young as five. In schools, first there's evidence it's connected to cognitive development, the ability to learn, and executive development which is the ability to control ourselves," Louv says.

At the same time, there's growing evidence that lack of time in nature is linked to rising rates of depression, attention deficit disorder and other health conditions, Louv says.

"An emerging body of scientific evidence suggests not spending much time outdoors connected to the natural world can be connected to rising rates of depression, attention deficit disorder, Vitamin D deficiency (an epidemic in the world), and child obesity."

There are a couple of theories about why exposure to nature is so beneficial.

The "biophilia" theory says humans are hard-wired genetically for an affiliation with the natural world and suffer when they're deprived of it.

A second school of thought is called Attention Restoration Theory (ART), which has been the basis of recent studies by Canadian researcher Marc Berman. It suggests the brain relaxes in nature, entering a state of contemplative attention that is restorative or refreshing. In contrast, in busy urban settings the brain's working memory is bombarded with distractions and attention systems are on alert.

Berman's research found a walk in nature could improve memory and mood in people diagnosed with depression.

Louv says there's enough evidence of the physical and mental health benefits of time in nature that schools should be mandated to include it in the standard curriculum.

He suggests families also make time for outings in wild places. He suggests creating or joining one of the growing number of family nature clubs that are popping up around the world (see a directory of them here).

Audio: Hear Richard Louv talking about the effects of a good dose of nature:

Louv says families are so busy, spending time in nature has to be a conscious choice. But it's one he passionately advocates.

Audio: Hear Richard Louv tell his personal story of how he became convinced of the benefits of nature:

You can watch a video about Louv's work here, and hear him describe the sense of wonder that nature inspires in many people.