A sun worshipper could be after more than a perfect bronze glow as sun light may cause physical and psychological dependence. On some people, soaking up the sun may have the same effect as opiates. A study published in the Journal of Cell found that like heroin, ultraviolet light boosts the production of beta-endorphins, 'feel-good' chemicals released by the body.
Researchers studied mice, which had the hair on their backs shaved and were then exposed to strong UV radiation five times a week for six months. The exposure was comparable to a sun-bather lying in the sun for half an hour.
These tanning sessions led to an increased production of beta-endorphins, which bind the same receptors as opioid drugs, such as heroin.