We need exposure to ultraviolet (UV) radiation from the sun. Ultraviolet radiation stimulates production of vitamin A, which, in turn, is used in the production of melatonin, a key neurotransmitter. Without proper melatonin levels, humans may fall into a depressed state.
Too much UV radiation can accelerate the appearance of wrinkles and other signs of aging by destroying collagen and elastin. The sun's damaging effects on the skin is a specific form of external aging called photoaging. In addition to destroying the collagen found in skin tissue, over time UV radiation lowers the body's ability to produce new collagen to replace what was lost to radiation.
There are some sensible ways to ward off sun damage. Dermatologists recommend regularly using a sun block with a sun protection factor (SPF) of 15 or higher when going out in the sun [source: AAD]. Additionally, covering skin with clothing offers substantial protection from UV rays.
Some foods also offer protection from sun damage. In one study, an ointment of 50 milligrams of green tea extract was applied three times weekly to the skin of rats. As a result, skin cancer rates declined 67 percent over 28 weeks of UV radiation exposure [source: Watson].