Published on January 12, 2012
Over time, skin ages and loses its youthful appearance. Wrinkles appear around the eyes, fine lines bloom around the lips, and age spots surface on the hands. While some of these factors are natural and unavoidable, many of the visible signs of aging are caused by the sun, and can be avoided.
Skin is composed of three layers: the epidermis, or outermost layer; the dermis, or middle layer; and the subcutis, or basement layer. The dermis contains collagen, elastin, and other fibers that support the skin's structure. It is these elements that give skin its smooth and youthful appearance – and that are damaged by UV radiation (UVR).
The UVR that affects the skin is composed of two different types of waves, UVA and UVB. When UVR hits the skin, cells in the dermis scramble to produce melanin to the epidermis. This is the process that gives you a tan, which is really just your skin attempting to block the radiation from penetrating your skin.
UVB rays are shorter than UVA rays, and are the main culprit behind sunburn. But it is the UVA rays, with their longer wavelength, that are responsible for much of the damage we associate with photoaging. UVA rays penetrate deep into the dermis, where they damage the collagen fibers. This damage causes increased production of abnormal elastin. The unusual amounts of elastin result in the production of enzymes called metalloproteinases. These enzymes, which rebuild damaged collagen, often malfunction and degrade the collagen, resulting in incorrectly rebuilt skin. As this process is repeated with daily UVA exposure, the incorrectly rebuilt skin forms wrinkles, and the depleted collagen results in leathery skin.
Repeated sun exposure can also cause what are commonly called age spots, or liver spots. They don't have anything to do with your liver, but have everything to do with sun. An ‘age spot' is actually a solar lentigo - a small bit of pigmentation caused by sun exposure. Age spots are usually found on the hands, arms, and face, and on the back in men.
The best way to combat photoaging is through prevention. Daily application of sunscreen with an SPF of 15 or higher to areas vulnerable to photoaging will not only help prevent photoaging, but can reverse some of the signs you might already have. And reducing your exposure to UV radiation will lower your risk of developing skin cancers and precancers.