The genetics of the human circadian clock

Daily rhythms of behavioral and physiological processes are believed to arise from endogenous circadian clocks. Unlike model organisms, genetic studies of human behavioral traits present extra challenges due to many factors such as the heterogeneous genetic background and environmental influences. Identifying molecular components of the human circadian clock were not possible until the recognition of Mendelian circadian traits in human subjects in recent years. Characterizing these rare Mendelian traits therefore established the foundation for identification of the genetic components for human circadian and sleep mechanisms. This line of investigation has proven fruitful and provided new insights into these pathways. Genetic association studies have also offered many possible genetic contributions to these mechanisms. Studies of these genes/proteins in conjunction with modeling human mutations in model organisms afford the opportunity to unravel the molecular mechanisms which in time will lead to pharmacological interventions that may not only help modify these behavioral traits but also may prove effective for treating other sleep-related disorders.