Sunlight and  Cancer
The connection between Vitamin D deficiency and cancer was first made by Drs. Frank and Cedric Garland from the University of California, San Diego. After finding that the incidence of colon cancer was nearly three times higher in New York than in New Mexico, the Garland brothers hypothesized that lack of sun exposure, resulting in a vitamin D deficiency, played a role. Research now indicates that being deficient in vitamin D increases the risk of many cancers, especially breast and colon. For example, a four-year, placebo-controlled study involving 1,179 postmenopausal women concluded that vitamin D supplementation produced a dramatic 60% drop in the risk of developing any form of cancer. Another study published in the September 2008 "Clinical Journal of the American Society of Nephrology" noted a reported 30 to 50 percent reduction in the risk of certain cancers with an increase in sun exposure.

Sunlight and  Psoriasis
Exposure to sunlight is extremely beneficial for individuals with psoriasis. In one study, an outdoor four-week sunbathing therapy was shown to promote significant clearance of psoriatic symptoms in 84 percent of subjects. "The sun is one of the best treatments for psoriasis, so in summer I encourage my patients to sit out on the deck and give their affected areas a good sunbath," said Julie Moore, M.D., a dermatologist at Gottlieb Memorial Hospital. "30 minutes is adequate to improve the skin; you do not need to sit out for hours." The ultraviolet rays in the sun are beneficial to the irritated skin.

Sunlight and Mood
During periods without sunshine, many people suffer from depression. It’s called seasonal affective disorder (SAD). Besides feeling gloomy, people experience low energy. Scientific research has examined the frequently observed relationship between sunlight and mood. A study from Denmark, published in the September 2011 issue of the "Scandinavian Journal of Work, Environment and Health," demonstrated that outdoor work, even in the winter, provided enough sunlight to counteract mood difficulties. Researchers found that regardless of the season, the turnover of serotonin in the brain was affected by the amount of sunlight on any given day. And the levels of serotonin were higher on bright days than on overcast or cloudy ones. In fact, the rate of serotonin production in the brain was directly related to the duration of bright sunlight.