Genetic basis for sleep regulation and sleep disorders.

Sleep disorders arise by an interaction between the environment and the genetic makeup of the individual but the relative contribution of nature and nurture varies with diseases. At one extreme are the disorders with simple Mendelian patterns of inheritance such as familial advanced sleep phase syndrome, and at the other extreme are diseases such as insomnia, which can be associated with a multitude of medical and psychiatric conditions. In this article, we review data on the relative contribution of genetic and environmental factors in the pathogenesis of various sleep disorders. The understanding of many of these disorders has been advanced by the study of sleep and circadian rhythms in model laboratory organisms. We summarize this model system research and how it relates to human sleep disorders. The current challenge in this field is the identification of susceptibility genetic loci for complex diseases such as obstructive sleep apnea. We anticipate such identification will increase our ability to assess risk for disease before symptom onset and by doing so will shift the focus from treatment to prevention of disease.