Tanning could be an addiction in the same way as alcoholism or a drug habit, warn researchers.
The suggestion could explain why so many men and women continue to bake in the sun or use sunbeds despite being aware of the risks of skin cancer. The disease claims around 1,700 lives a year in this country. Experts believe around 100 of those are caused by sunbeds.
The latest research from the U.S. suggests the root cause of the addiction may be feel-good chemicals called endorphins, according to Daily Mail.
Previous studies have shown ultraviolet light stimulates the release of these substances in the bloodstream, producing a natural high. For many teenage girls, the quest for a tan to match that of their favourite celebrity has turned into an unhealthy obsession, termed "tanorexia" by British doctors.
The American researchers asked nearly 150 beachgoers questions adapted from papers used to diagnose alcoholism and drug addiction. These included: "Do you try to cut down on the time you spend in the sun but find yourself still sun-tanning?" and "Do you think you need to spend more and more time in the sun to maintain your perfect tan?".
From their answers, up to half could be classed as being "ultraviolet light tanning dependent" - or addicted to tanning, according to research published today in the medical journal Archives of Dermatology.
Lead researcher Professor Richard Wagner, of the University of Texas, said: "Dermatologists often talk about people who seem 'addicted to the sun' - people who know it's not good for them to be bronzed but don't seem to be able to stop tanning.
"By slightly modifying tools used to identify substance-related disorders, we can actually see an objective similarity between regular tanning and these disorders."
Professor Wagner added: "There has been mixed evidence from other studies suggesting that tanning increases endorphin production, which could be addictive."
A spokesman urged the public to protect their skin by seeking shade during the hottest part of the day, by covering up and by using high factor sunscreen.
Numerous campaigns about the dangers of sunbathing have failed to halt the rise of skin cancer, with more than 6,000 new cases of malignant melanoma - the most deadly type of the cancer - diagnosed in the UK each year.