Recent interest in visible light protection has given rise to a reemerging question: Is visible light harmful to skin? If one considers the basic tenets of toxicology, everything can be toxic at a given dose. So yes, visible light can be harmful.

Perhaps the more poignant question would be: To whom is it harmful, and when? Or: Do the benefits of visible light outweigh its potential toxicity?

But before exploring these relevant considerations for skin care, it is important to step further back and ask: Upon its arrival to the earth’s surface, what happens to all the energy contained in visible light? And, for starters: What is visible light? This brief commentary considers the latter, to answer the former.

What is Visible Light? What we call visible light is that which falls in the region of the electromagnetic spectrum between the wavelengths of 400-700 nm. This is detectable to the naked eye of most healthy human beings. Not all vertebrates detect and distinguish all the wavelengths in this region, and in some cases, the eyes of other animals detect electromagnetic wavelengths outside of this region. The description of the mechanisms of human vision is beyond the scope of this short review.

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