Behavioral Neuroscience Comprehensive Exam Question Sleep behavior is heavily influenced by interactions between circadian and homeostatic

Sleep behavior is heavily influenced by interactions between circadian and homeostatic mechanisms. These interactions, which have been modeled by Borbely and others, vary across individuals, between the sexes, and among species, and they change across the lifespan. In some species, like us, they typically produce a relatively long sleep bout at one time of day whereas in other species, like rats, they produce a pattern of many shorter bouts whose frequency and duration vary across the day-night cycle. A great deal is known about the neural substrates mediating sleep/arousal state, and researchers are just beginning to get a handle on how these systems are influenced by neural mechanisms mediating circadian and homeostatic influences on sleep. Very little is known about how these mechanisms differ in species with relatively long consolidated sleep bouts and ones with shorter more frequent bouts whose patterning changes from day to night. Most of the research on these mechanisms is done on the latter species (e.g. rats) although the general aim is to understand the former (e.g. humans).