Harvard Women's Health Watch

LED photomodulation: "Light" way to skin renewal

Acquiring a more youthful look often involves sanding, peeling, or heating the skin. A new painless technique relies only on low light.

At one time, women could get a lasting younger look only by a surgical facelift. Then came skin-rejuvenation techniques that produced more natural-looking results: dermabrasion, chemical peels, and ablative laser resurfacing. In these procedures, the outer layers of skin are removed (ablated) to spur wound healing and the growth of new collagen and skin cells (see "Skin structure and skin aging"). But the process hurts, and recovery can take days or weeks.

Skin structure and skin aging

On the skin's outermost layer — the paper-thin epidermis — old cells continually die, flake away, and are replaced by younger cells that rise up from the lower epidermis. This process renews the skin about once a month.

Beneath the epidermis is a thicker layer called the dermis, which contains substances such as collagen and elastin, and structures such as blood vessels, oil glands, and nerves. Collagen, a structural protein, is arranged in layers of fiber called fibrils, forming a matrix that holds the skin together. Elastin, a protein similar to collagen, gives skin its elasticity. Beneath the dermis is a layer of fat.

As we age, the dead cells don't slough off as easily, so the surface of the skin becomes rougher. Less moisture is retained and less collagen and elastin are produced, so the fibril layers loosen and become less organized, causing skin to sag. Losing collagen and elastin, the skin becomes thinner, so fine lines appear around the eyes, and deeper lines occur at the mouth and across the forehead.

All these changes are accelerated by exposure to sun. In fact, damage from sun exposure, also called photoaging or photodamage, is the source of most facial lines and wrinkles. Smoking also prematurely ages the face by damaging collagen and elastin and impairing blood circulation to the skin.

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