A new study suggests it is possible to be addicted to tanning.
Researchers at Massachusetts General Hospital exposed mice to a daily dose of UV radiation for six weeks.
After a week of exposure, researchers found elevated endorphin levels in the mice.
Those are "feel-good" hormones that have an impact similar to heroin.
The mice were then given a drug to block the feel-good hormones. They experienced symptoms of withdrawal.
While they study is in mice, researchers say it proves UV exposure could trigger addictive behaviors.