Approaches to unravel the genetics of sleep.

Sleep and circadian rhythms are complex and inter-connected physiological processes. Relative to the remarkable progress made in identifying the genetic basis of circadian rhythms and some specific sleep disorders, efforts to identify genetic variants associated with normal variation in sleep have progressed more slowly. Two key issues concerning the design of such studies must be addressed in order to facilitate further progress. The first concerns the sleep related traits to be targeted. The second issue is the choice of the gene-mapping method (linkage, candidate gene association or genome-wide association). This paper discusses these issues, reviews published studies of sleep phenotypes, and recommends cost-effective methods to advance knowledge of the genetic determinants of normal sleep patterns.