A new study in the March issue of SLEEP demonstrates that there is a considerable cross-talk between the circadian and homeostatic processes.  The authors concluded that as the clock gene Per2 in the brain responds to both sleep loss and time of day, the molecule is well positioned to keep track of and to anticipate homeostatic sleep need. “Overall, this study adds to the case that clock genes not only underlie circadian and homeostatic aspects of sleep regulation, but that there is a fundamental link between the two processes,” states a commentary on the study.