A new study led by David Fisher at the Harvard Medical School was able to show that mice were “addicted” to the beta-endorphins released by tanning.
When exposed to UV light, your skin (and mice skin!) activates a gene that creates a peptide called proopiomelanocortin.
Proopiomelanocortin then becomes α-melanocyte-stimulating hormone which increases the amount of melanin in the skin – creating a tan.
A by-product of this process is beta-endorphin. You might know a bit about beta-endorphin (like how it’s released when you eat chocolate and other treats!), but it works on opioid receptors in our brain and body. This causes pain reduction and can create addiction.
So in this study, the researchers found that mice exposed to UV light exhibited different behaviour when given Naloxone. Naloxone is an opioid receptor blocker and stops the effects of the beta-endorphin that is released during tanning.
Mice naturally like being in dark places. Mice that were exposed to UV light and not given Naloxone, stayed in a dark box. However mice that were exposed to UV light and given Naloxone, left the dark box – they associated the dark box with their withdrawal symptoms.
What this showed was that the beta-endorphins released by tanning had an effect on the behaviour of the mice.
They also studied modified mice without beta-endorphin receptors, and they showed no changes in behaviour after tanning.
You can read the full study here – Cell: Skin β-Endorphin Mediates Addiction to UV Light
Other studies have looked at behaviours in humans when tanning.
For example one study found that people were able to tell the difference between a real tanning bed and a sham tanning bed that was just non-UV light. People said that the real tanning bed made them “feel better” – remember that they didn’t know there were fake tanning beds!
You can read that study here – The American Journal of Drug and Alcohol Abuse: Tanning as a Behavioural Addiction