Keeping time with the human genome

The cloning and characterization of 'clock gene' families has advanced our understanding of the molecular control of the mammalian circadian clock. We have analysed the human genome for additional relatives, and identified ne w candidate genes that may expand our knowledge of the molecular workings o f the circadian clock. This knowledge could lead to the development of ther apies for treating jet lag and sleep disorders, and add to our understandin g of the genetic contribution of clock gene alterations to sleep and neurop sychiatric disorders. The human genome will also aid in the identification of output genes that ultimately control circadian behaviours.