Physiologie de l'horloge circadienne endogène : des gènes horloges aux applications cliniques

A large number of biological activities such as hormonal secretion, cognitive performance, motor activity, the sleep wake cycle, and, most recently evidenced, cell division and ADN repair, show a 24-hour rhythmicity that is driven by the circadian timing system (the clock). Their appropriate expression over the 24 hour requires appropriate entrainment of the circadian clock, which is achieved though the synchronizing effects of ocular light exposure. A deficit of circadian entrainment to the 24 hour is responsible for alterations of the physiological functions under its control, and leads to altered sleep, wake, mood, neurobehavioral processes, and cell division. Circadian sleep disorders and some depressions can be efficiently treated using circadian principles and chronobiological approaches, such as phototherapy.