Spending time outdoors increases our exposure to sunlight. Before you run for cover, listen to this: it is believed that sunlight deficiency is linked to a high incidence of irritability, fatigue, illness, insomnia, depression, alcoholism, and suicide. Sunlight is healthy! Once sunlight reaches your eyes and is registered by the brain, your entire body is affected in a positive way. We depend on the energy of sunlight to catalyze many processes in the body, including our ability to burn fat and get rid of toxins.
Research by photobiologist John otts suggests that this is true of full-spectrum natural sunlight only, not partial sun. In addition, studies indicate that we as a nation—because of all the time we spend indoors these days—are experiencing a mass vitamin D deficiency (there’s a simple blood test you can take to see where you stand). Age, obesity, dark skin, and illness increase your risk for this deficiency, as does living in the Northern part of the country or if you are a sun-phobe or a sunblock lover. Vitamin D deficiency is also linked to osteoporosis and rickets in children, plus hip fractures, autoimmune disease, several types of cancer (including skin cancer), diabetes, cardiovascular disease, and depression.
Sunlight is the main source of vitamin D for humans. This, for me and for many other concerned public health professionals, is another reason to get outdoors when we exercise. however, this doesn’t mean that we can hang out in strong sunlight for hours on end. According to integrative physician Dr. Frank Lipman, as a general rule if you are not vitamin D deficient, about 20 minutes a day is adequate in the spring, summer and fall without sunscreen on your arms or legs. In the winter the sun is not strong enough to generate enough vitamin D north of 37 degrees latitude (the latitude of San Francisco) no matter how long you’re outside.
A few safety rules apply. Never, ever stay out long enough to get a sunburn. You need to be especially careful if you have fair or sensitive skin or a personal or family history of skin cancers, or if you are taking medication that makes you sun sensitive. It is preferable to go out in the early morning or later in the day when the sun is weak or has gone down. Wear protective clothing if you can’t avoid too much sun. I also suggest that you seek out tree-shaded benches or those under a gazebo. I’ve seen great gazebos and shade pavilions in Florida, where the sun is strong all year round. In winter, in climates far from the equator, most people don’t need to worry, but if you live in or visit the southern latitudes, ask your dermatologist to recommend a nontoxic brand of sunscreen. sunlight’s benefits make sense because we evolved in the sun; we were made to get some sun, not to live our lives indoors or have to coat ourselves with sunscreen every time we go outside. Remember also to take antioxidants when you sit in the sun, as these can help prevent skin cells from sun damage.