Wrinkles are caused by a breakdown of collagen and elastin. As we age, collagen and elastin degrades on its own just from time. But, sun exposure can accelerate this degradation. If you get a lot of sun exposure on your skin, these collagen fibers start to uncoil. Think of them as three or four wound ropes that keep the skin taut and give the skin its snap- when you lift it up, it snaps right back down. Non-wrinkled skin is well hydrated, has really healthy, young collagen and elastin. Elastin is the rubber band that’s found among these collagen fibers that also contributes to its snap or its overall structural stability.
Sun exposure can accelerate both elastin and collagen degradation. Over time you lose the rubber band that’s found alongside these collagen fibers. The result is, as you know, loose, sagging skin with wrinkles because they lose the tautness or the strength of that younger collagen and elastin.