“Adam” was a 14-year-old boy who I was asked to see for symptoms of anxiety and depression. His parents were concerned about him and asked if he needed vitamin supplements or an antidepressant. During my assessment, I discovered that Adam, whose real name I’m not using to protect his privacy, was having trouble sleeping, had low energy and poor focus, and was experiencing anxiety and irritability about simple things (like a change in his routine).

Since Adam’s symptoms were still in the “mild” category, he would likely experience a significant benefit from a change in his lifestyle, and my recommendation was to try that before any medication. Although Adam did not have a serious mental health issue (yet), he did have a serious lifestyle issue. When I asked him how much fresh air and sunlight he received per week, he asked me if being in his car with the windows open counted! I said no, so he told me that between his hockey practice, homework and playing video games, he spent less than two hours outside a week – and that was essentially only when he walked to and from wherever his mom parked her car when she picked him up.

My first prescription for Adam was to get out into the great outdoors. For 99 percent of human history, we’ve lived in the natural environment and our brains have adapted to find balance and health in that setting. But more recently, we have become increasingly disconnected from nature with profound negative consequences on the growing brain of children and adolescents.

Here is how nature can help with symptoms like those Adam experienced:

It can improve sleep. Regular daily doses of bright natural sunlight help children stay more alert during the day and make it easier to sleep at night. A known treatment for trouble sleeping at night is exposure to sunlight early in the morning, since this helps regulate our body’s natural sleep-wake cycle and internal rhythms.

Nature can boost energy levels. Even though it may take some time to kick in, most of us can relate to feeling more energetic while in nature. A 2010 study in the Journal of Environmental Psychology found that being in nature increased one’s sense of vitality, happiness and energy. In addition, playing outside encourages activities such as climbing, jumping, running and tumbling that promote muscle fitness and flexibility. Research shows that moderate to vigorous physical activity in child care settings increased from 1 percent indoors to as much as 11 percent outdoors. When outdoor play was child-led, the amount of moderate to vigorous physical activity further increased to 17 percent. Cardiovascular exercise itself is a natural antidepressant as it releases soothing endorphins into the bloodstream and can help with the production of sleep-inducing melatonin.

Being outside can reduce stress and negative emotions. Just looking at a natural scene activates parts of the brain associated with balance and happiness. A South Korean study found that subjects who saw images of mountains, forests and other landscapes experienced heightened activity in a part of the brain called the anterior cingulate gyrus, which is linked to optimism and emotional stability, and the basal ganglia, which is linked to the recollection of happy memories. A Scottish study showed subjects who walked through a rural area viewed their to-do list as more manageable than those who walked on city streets.

It can improve focus and attention. The Attention Restoration Theory suggests the brain relaxes in nature, entering a state of contemplation that is “restorative or refreshing.” In contrast, in urban environments, the brain’s working memory is “bombarded with distractions and attention systems are on alert.” A study in the American Journal of Preventive Medicine found that children who played outdoors gained creativity and problem-solving skills as well as cooperation skills and self-discipline, and children with attention deficit hyperactivity disorder seem to focus better after being outdoors.

Spending time outside can help reduce symptoms of anxiety and depression. Norwegian researchers discovered that subjects with moderate to severe depression who participated in a gardening program experienced reduced symptoms after 12 weeks. There are plenty of antidepressants in nature, including sunlight and “negative ions” – particles found near waterfalls, breaking waves and river rapids. A study found that breathing negative ions for an hour lead to subjects’ blood lactate levels dropping by 33 percent, improving their energy levels.

I told Adam and his parents that these are just the mental health effects of nature and that there are loads of physical health benefits as well. Research suggests that rising rates of allergies and autoimmune disorders may be linked to less exposure to healthy bacteria found in nature. In addition, reduced exposure to nature is linked to higher risk for obesity, cancer and heart disease, and the farther you live from green space, the likelier you are to be in poorer health. Humans are biophilic, meaning we have a love of nature, and we are biologically driven to be there. Nature keeps us healthy.