Like your other body organs, your skin begins to slow down its functions as you age. As levels of estrogen and progesterone decline, skin becomes drier, thinner, and secretes less oil. Circulation decreases, and wrinkles appear when collagen and elastin, proteins in the skin that provide elasticity, break down. The rate of cell production and turnover decreases, and cells grow thicker and more tightly packed together. Common signs of aging skin include unevenness of skin texture and pigmentation, wrinkles, and "age spots," the brown patches caused by accumulated sun damage that appear on the face, chest, and the backs of the hands.
However, most of the skin changes that are blamed on aging are primarily the result of long-term exposure to the sun's ultraviolet rays. Compare the skin on the underside of your arm (which rarely is bared to the sun) to the skin on your face. If your facial skin had never been exposed to the sun, it would probably not look much different at age 50 than it did at when you were 20. Sun damages not only the top layer of skin, but the underlying supportive layer of collagen and elastin as well, which causes wrinkling and sagging.
Fortunately, it's never too late to begin improving the condition of your skin because skin cells have the ability to repair at least some of the damage caused by the sun's ultraviolet rays. Studies show that women who use a sunscreen daily experience significant improvement in the condition of their skin after only six months. Obviously, the degree of improvement is related to how much sun damage you have incurred, but the important point is that avoiding further sun exposure will help you have better-looking skin. Use a sunscreen with an SPF (sun protection factor) of 15 or higher every day, even during the winter and on cloudy days, and make sure that the sunscreen you are using blocks out both UVA and UVB rays. While using an SPF 15 sunscreen allows you to stay out in the sun 15 times longer than you normally would be able to without burning, the best way to prevent sun damage is to avoid direct sun exposure when the sun's rays are the strongest, which is usually between the hours of 10 A.M. and 3 P.M. If you are outdoors during those hours, make an effort to stay in the shade as much as possible, and use physical barriers such as tightly woven long-sleeved clothing, sunglasses, and a broad-brimmed hat.