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UV light may have a drug-like effect, leading to addiction and even withdrawal symptoms.
Evidence for a UV high. I’m Bob Hirshon and this is Science Update.
Ultraviolet light may act like an addictive drug. This according to David Fisher, chair of dermatology at Massachusetts General Hospital and Harvard Medical School.
He says habitual tanners show some hallmarks of addiction, and prior evidence suggested a link to the opiate pathway – which is also activated by drugs like heroin. Now, in mouse studies, his team showed that even mild UV exposure releases a natural opiate called beta-endorphin, numbing pain and other sensations. Opiate-blocking drugs abruptly stopped this effect.
And what we observed is that the mice started to exhibit very clear symptoms, quantifiable symptoms, of withdrawal.
What’s more, mice that couldn’t produce beta-endorphin were immune to the effect entirely. The results could help explain why some people feel drawn to tanning, even though they know it’s unhealthy. I’m Bob Hirshon for AAAS, the Science Society.
Making Sense of the Research
Decades ago, a suntan was considered healthy, but nearly everyone knows better now. Tanning is strongly linked to skin cancer, as well as premature aging in the form of wrinkles and blotches. But while people today are more likely to use sunscreens for a day at the beach than they were, say, in the 1970's, indoor tanning remains popular. In indoor tanning booths, people directly expose themselves to the ultraviolet (UV) light that causes cancer and these other forms of damage.
So why do it? We can understand why people smoke or use illegal drugs despite the health risks, because they provide an immediate “buzz” or high that feels good in the short-term. Getting an indoor tan doesn't seem like quite the same thing. But according to this study, it may be more similar to tobacco and drug use than we suspected.
Past research has found similarities between indoor tanners and people addicted to drugs or other substances. For instance, a 2010 study in the Archives of Dermatology interviewed 421 college students, about half of whom used indoor tanning beds. They asked questions about feelings and attitudes toward tanning – for instance, whether they woke up in the morning thinking about it, or wanted to stop but felt they couldn't – which could indicate addiction. Roughly a third of the frequent tanners met the criteria for addiction in their answers.
This study looked at a possible pathway for addiction at the cellular level. The researchers studied mice, some of which were exposed to the kind of UV light used in tanning beds. Even after a single, relatively small dose (for the mouse's size), the UV light activated a pathway that released a feel-good, pain-numbing molecule called beta-endorphin. Other addictive substances that act on the beta-endorphin pathway include opium and morphine.
The mice exposed to UV also showed behavioral symptoms of withdrawal when the UV exposure stopped, or when they were given drugs that blocked the beta-endorphin pathway. Furthermore, mice that were genetically engineered to lack beta-endorphins didn't respond to UV light at all.
Taken together, these separate pieces of evidence suggest that UV light can stimulate the production of beta-endorphin, which makes tanning feel good and keeps users coming back for more. The findings suggest that people who are hooked on indoor tanning may not respond to health warnings alone; they may need some form of substance abuse treatment.
Now try and answer these questions:
- What is indoor tanning? Why is it a health hazard?
- What past evidence suggested that UV exposure may create a form of addiction?
- How did the researchers use several different mouse experiments to test the addiction hypothesis? What did each of these experiments specifically demonstrate?
You may want to check out these related resources:
The interactive SCI: Skin Cancer Investigation gives you the opportunity to learn about skin cancer diagnosis and prevention.
- Skin Cancer 1: Exposing Healthy Skin to the Sun
- Skin: The Behavior and Health Connection
- SCI: Skin Cancer Investigation
- You and Your Skin
- UV Disinfectant
The interactive tool SCI: Skin Cancer Investigation gives students the opportunity to learn about skin cancer diagnosis and prevention.
The Skin Deep Project is a collection of resources that help students take a closer look at our largest organ, and learn how we can keep it healthy.