In the August issue of the Archives, Keen et al1 discuss recent clinical evidence that UV-seeking behavior should perhaps be seen as an addictive disorder.2,3 This insight is important because it implies that excessive tanning behavior should be approached as a form of substance abuse and that altering patients' sunning habits will not be a trivial matter. Unfortunately, Keen et al do not mention recent molecular and clinical data supporting the idea that excessive UV tanning behavior results from an addiction to endogenous opioids.4,5 I believe that these recent data strongly justify treating excessive sun-seeking behavior as an addiction. This idea has important implications for dermatologic practice, and the recent report describing its possible molecular background4 may have escaped most readers' attention.