Fisher said this suggests that the mice were building up a level of tolerance to the UV exposure. In other words to produce the same beta-endorphin-boosting effect, the mice required more time in the UV light. The scenario is similar to addicts who require more of their drug to achieve the same high.
The mice also displayed some classic signs of withdrawal behaviors including shaking, tremors and chattering teeth.
As Fisher told New Scientist, "We have a propensity towards seeking the most common carcinogen in the world."
Do we really all carry the potential to become sun addicts? The notion makes some evolutionary sense since our bodies require vitamin D and require some sun in order to synthesize the vitamin.
Some health experts, however, take exception to the comparison between overdoing it in the sun and becoming hooked on heroin.
"Even if an individual truly has no control over their compulsive behavior – even if they experience highs and lows, tolerance and withdrawal – that doesn't necessarily make someone an addict," cautioned Carlton Erickson, who works on addiction at the University of Texas at Austin.