Ultraviolet Light May Actually be Addictive, Study Says
It’s no secret that tanning is dangerous. We’ve all heard the warnings about skin cancer and premature aging, yet we find ourselves laying out in the sun sans protection anyway. If you think your insistence on sun worship is just a vice, researchers from Harvard Medical School and Massachusetts General Hospital have some news for you—it may be an addiction.
In a study published in the June 19 issue of Cell, scientists found that exposure to ultraviolet (UV) radiation not only releases endorphins, but also produces addictive, “opiate-like effects.” Scientists observed these results in mice, which were administered a daily dose of UV light for six weeks. According to a Harvard Medical School report:
Within a week of the first UV exposure, levels of beta-endorphin in the animals’ blood rose significantly, remaining elevated during the study period and gradually returned to normal after UV exposure was discontinued. Tests conducted at regular intervals during the study period showed that the UV-treated animals were less responsive to light touch or temperature changes than a control group with no UV exposure. The higher the animals’ beta-endorphin levels, the less sensitive they became. But administration of naloxone, which would broadly block opioid-pathway activity, returned skin sensation back to normal in the UV-treated animals.
In UV-habituated animals, naloxone treatment also produced classic symptoms of opioid withdrawal, such as trembling, shaking and teeth chattering.
David E. Fisher, the study’s lead author, told Harvard Medical School that because exposure to sunlight contributes to the production of vitamin D, it’s possible that human sun-seeking behavior developed as an evolutionary adaptation.
“Such behavioral effects would also carry the carcinogenic risks of UV light that we now recognize,” Fisher said. “Today’s alternative sources of vitamin D, such as inexpensive oral supplements, are both safer and more accurate in maintaining healthy vitamin D levels.”