Here’s how photoaging, or aging caused by the sun, accumulates:
A is for aging, B is for burning. There are two key types of ultraviolet radiation -- UVA and UVB light -- and both ravage skin, damaging its DNA, provoking cancer, and accelerating wrinkles, sagging, and other signs of time. UVA has been dubbed the aging ray because, over time, the dermis damage it does produces wrinkles and pigment changes. UVB, the burning ray, triggers inflammation and dilates blood vessels -- sunburn. Any time you get tanned, it means you’ve damaged your skin. Your body has upped its production of melanin pigment, which acts as a UV filter, in an attempt to shield skin from photodamage.
Skin fights back. As sunlight penetrates your skin, it batters your DNA. UVB attacks DNA directly, UVA also damages cells and DNA but penetrates even more deeply, which is why it’s dubbed the silent wrinkler, as it goes much deeper than the other rays to cause a delayed tan, delayed wrinkling, and delayed skin cancer. These rays injure a host of cells, including fibroblasts, which produce collagen and elastin. The skin’s stress response system signals an alert and defensive cells rush in to undo the harm, but the result is never quite like new. What’s more, both types of UV appear to eventually suppress the immune system, which may be a factor in melanoma, the most serious kind of skin cancer.
Sag sets in and spots surface. Gradually, collagen breaks down and becomes disorganized and abnormal elastin increases, so skin loses its stretchiness and becomes looser, saggy, less resilient, and more wrinkled. Production of melanocytes, skin’s pigment-producing cells, becomes erratic, making skin tone uneven, blotchy, and spotted.
Red spreads. UV rays encourage the creation of new blood vessels, which may give you a sprinkling of telangiectasias -- spidery red spots -- and help skin cancers form. Skin usually thins with age, but regularly sun-exposed skin on the back of your neck will get thick and leathery as a defensive reaction to UV light.
From The Mind-Beauty Connection: 9 Days to Less Stress, Gorgeous Skin, and a Whole New You by Amy Wechsler.