LIGHT THERAPY

You've seen those LED face masks on social media and may be wondering, "Do they work?" The answer is more than a simple "yes." In fact, experts are just beginning to understand how this energy and the sun's rays profoundly impact skin.

- BY BRIAN UNDERWOOD

What's the first thing you think of when you hear the word light? It's likely something with a positive association-like the phrase "see the light," for example, or the proverbial lightbulb that appears above a cartoon character's head when a brilliant idea strikes. Maybe it's the brightness of a warm summer day. The point is that we generally consider light to be good, safe, even comforting. Yet when it comes to our skin, things are a bit more (maybe a lot more) complicated.

It's well established that many of the cells within our dermis and epidermis-the fibroblasts that produce firming collagen, the melanocytes that churn out protective pigment-are responsive to myriad wavelengths of light. In some cases, it's a response we want: Dermatologists have been using light therapeutically for years, for medical and aesthetic purposes. At other times-say, in the development of a painful sunburn or skin cancers-light can have a decidedly negative effect.

For some time, the "how" of all this was a bit murky. But over the past decade or so, scientists began to understand more about this fascinating cascade. One of the most interesting discoveries is that opsins-a class of light-sensitive proteins found in the rods and cones of our eyes that play a key role in our vision are also present in skin.