The circadian system has been implicated in the control of alertness and clock genes have been associated with sleep and mood disorders, such as familial advance sleep phase syndrome (FASPS), depression, mania or bipolar disease (BD) [1]–[8], and therapeutic approaches modulating the circadian system (‘chronotherapy’) may be promising to improve treatment of psychiatric diseases [9], [10]. This evidence concerns the gene CLOCK and Familial advanced sleep-phase syndrome.