It’s an idea that emerged about a decade ago. Sunbathers are addicts. Tanning is a true addiction. The idea got a big boost last week with a paper published in Cell offering evidence of a pathway for tanning addiction. Studying mice, the researchers found that UV light led to the synthesis of β-endorphins in the skin, the same opiate-like compound our bodies produce when we exercise. And when the mice were then given the opiate-blocker naltrexone, they had signs of opiate withdrawal. So we understand a little more about that good feeling we get lying out in the summer sun. Or the more surprising behavior of people who can’t stay away from the tanning salon. It’s not just vanity.

The article ends with strong language and a powerful alarm:

The current studies suggest that UV exposure is biologically addictive but dangerous due to UV’s mutagenic activities toward formation of all common forms of skin cancer. This calls into question the perceived safety of tanning beds and current benign views of indoor tanning… It may be necessary, therefore, to more proactively protect individuals, including teens, from the risks of an avoidable, potentially life-threatening exposure and to view recreational tanning and opioid drug abuse as engaging in the same biological pathway.

So how do we put this together with the overwhelming evidence of the benefits to our health from bright light and sunshine? And the evidence that modern life has already made most of us light-deprived?

The answer is simple. Other than vitamin D, all those benefits of bright light come from visible light through our eyes, not UV light on our skin. Sunscreen and clothing do not get in the way. And sunlight in the early morning, when the benefits of bright light are greatest, contains very little UV radiation, which rises rapidly in the middle hours of the day. We don’t need to hide indoors, tethered to a therapeutic light box for our bright light, afraid of the sun. We can have all the benefits of outdoor light with no tanning at all. And we can hope that the liveliness of our smile and the energy of our movements radiate health even without a tan.