Describes the physiology and neurobiology of sleep and impact of sleep, sleep deprivation, and sleep disorders on immune, endocrine, cardiovascular, respiratory, and neural systems, as well as examines changes in sleep across the life span. The integrative nature of sleep and circadian rhythms in normal physiologcial and cognitive function and their importance in health and disease processes will be emphasized. Prereqs. for IPHY 4850: MCDB 1150, 1151, 2150 and 2151 or EBIO 1210, 1220, 1230 and 1240; IPHY 2800 (or equivalent); IPHY 3470. IPHY 4580 and 5580 are identical courses. IPHY 5580 is restricted to graduate students only.