Humans didn’t evolve to be inside all day. Most people recognize intuitively that they are happier in a green park than a concrete parking lot. Now, there is growing evidence that spending time in nature is good for you. It improves your mental and physical health and it’s becoming a means of treating mental illnesses such as anxiety and depression.
For one thing, being in nature exposes you fresh air and sunshine. Exposure to sunlight allows your body to make vitamin D. A shortage of vitamin D has been linked to many health problems, including depression. Sunlight also wakes you up. Your circadian rhythm that determines when you’re tired and hungry is reset by sunlight. Spending a little time outside in the morning can promote a healthy biorhythm. As for fresh air, few people realize how poor the air quality indoors often is. There is more dust and carbon dioxide. There may be mold or bacteria. You typically get much better air quality outside, especially in areas with a lot of vegetation.
Natural areas are also good for your immune system. Studies have identified more than 20 ways in which nature improves the immune system. The most important may be related to inflammatory cytokines. These are immune cells that are released in response to an infection. Unfortunately, where there is no infection present, they only make you sick and miserable. Elevated levels of cytokines have been linked to heart disease and depression. Spending time in nature reduces the levels of inflammatory cytokines.
Other studies have shown that there are compounds in soil and released by plants that improve your mood. Compounds called phytoncides have been found to reduce blood pressure and improve immune function. Other compounds in the soil promote the release of endorphins, which make you feel better. This may be one reason people find gardening so relaxing.
Being outside also promotes exercise. What’s especially interesting is that exercise in nature improves your mood and lowers stress more than exercise in an urban setting. Several studies have made direct comparisons. One study from Stanford found that participants who walked for 90 minutes in a natural setting showed reduced activity in a brain area associated with depression. Another study, from Harvard, found that female nurses living in the greenest areas had 12 percent lower mortality than those living in the most urban areas. They also had lower levels of depression, to which the study’s authors attributed about 30 percent of the mortality difference.
Beyond the specific benefits that can be measured with a blood test or a brain scan, spending time in nature also improves your quality of life. It’s a break from constant distractions. Being immersed in nature makes you feel more connected to other living things, part of the ecosystem. It’s a way to be more fully present, even if it’s only for a little while. Spending more time in nature won’t necessarily cure depression or anxiety, but it can be an important part of a comprehensive recovery program.