Here Comes the Sunby Jennifer Gibson, PharmD | July 6, 2014
Summer is officially here and with it comes hot days, beach vacations, and lazy moments by the pool. While most Americans slather on the sunscreen to avoid even the slightest tint of sun-kissed skin, some die-hard sun worshippers gladly soak up whatever ultraviolet (UV) rays the rest of us have no use for.
The risks of too much sun exposure – skin damage and cancer, to name just a couple – are well known and most children and adults take appropriate preventive measures to avoid absorbing too much UV light. However, some people still crave the damaging rays – both outdoors and in tanning salons. Do these people just prefer a bronzed complexion or could they be addicted to sunshine in the way that others are addicted to substances or alcohol or foods? The authors of a new study in mice posit that it just might be the latter.
The paper, which is published in the journal Cell, reports that mice were exposed to a daily dose of UV light (the equivalent of 20 to 30 minutes of midday sun for humans) for 6 weeks. This exposure boosted levels of beta-endorphins, the “feel good” hormones that act in reward pathways in the brain. (Opioid drugs also act on these same pathways.) The authors claim that their findings are evidence that sun exposure is rewarding to the brain and, therefore, it has the potential to become an addiction.
Additionally, the sun-tanned mice were less responsive to temperature changes and sensory stimulation, which suggests analgesic effects of the UV light exposure. The authors assume this was due to the stimulation of the opioid pathways in the brain. Administration of the opioid-blocking agent naloxone triggered withdrawal symptoms in the mice.
Cravings for sun may not be purely cosmetic; the body does need some UV light to trigger the synthesis of vitamin D, so it is possible that humans just evolved to enjoy getting our daily dose of vitamin D. Still, the sun is not the only source of vitamin D – so is fish, fortified milk and juice, and supplements.
The incidence of skin cancer is rising by approximately 3% per year, but many people continue to tan despite the knowledge of the risks or a history of harm. These people are a long way from being enrolled in a tanning addiction treatment or rehabilitation plan, though. Most likely, there is a combination of psychological, social, and cosmetic factors that motivates the compulsive behavior. To date, studies conducted in humans surrounding UV light behavior have been small or limited in scope, but they do point toward behaviors that are consistent with symptoms of obsessive-compulsive disorder and substance use disorders.
More studies in humans are needed to determine if an addiction to sun is a legitimate and distinct diagnosis and, if so, what behavioral and pharmacological treatment options might look like. For now, continued education and improved awareness of the risks of sun exposure will hopefully overshadow a desire to continually bask in the sun.
Ashrafioun L, & Bonar EE (2014). Tanning addiction and psychopathology: Further evaluation of anxiety disorders and substance abuse. Journal of the American Academy of Dermatology, 70 (3), 473-80 PMID: 24373775
Fell GL, Robinson KC, Mao J, Woolf CJ, & Fisher DE (2014). Skin ?-Endorphin Mediates Addiction to UV Light. Cell, 157 (7), 1527-34 PMID: 24949966
Heckman CJ, Darlow S, Kloss JD, Cohen-Filipic J, Manne SL, Munshi T, Yaroch AL, & Perlis C (2013). Measurement of tanning dependence. Journal of the European Academy of Dermatology and Venereology : JEADV PMID: 23980870
Kourosh AS, Harrington CR, & Adinoff B (2010). Tanning as a behavioral addiction. The American journal of drug and alcohol abuse, 36 (5), 284-90 PMID: 20545604
Nolan BV, & Feldman SR (2009). Ultraviolet tanning addiction. Dermatologic clinics, 27 (2) PMID: 19254653
Warthan MM, Uchida T, & Wagner RF Jr (2005). UV light tanning as a type of substance-related disorder. Archives of dermatology, 141 (8), 963-6 PMID: 16103324
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