Sleep organization and regulation

Sleep is a vital, complex state with as yet unknown functions. It is active and highly organized and is regulated by homeostatic, circadian, and ultra dian processes. It consists of two distinct sleep states, rapid eye movemen t (REM) and non-rapid eye movement (NREM), both of which have a dramatic im pact on many aspects of physiology and behavior. The significance and conse quences of the REM-NREM organization of sleep are not known. On the other h and, the sleep state and its organization are quite fragile and dynamic. An y number of factors can disrupt sleep and its expression, and its nature ch anges over the life span. What is certain is that any reduction and/or disr uption of sleep hinders an organism's ability to navigate through the wakin g state.