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. IPHY 4580 and 5580 are identical courses. Prereqs. for IPHY 4850: one year of biology, one year of chemistry, IPHY 2800 (or equivalent) and IPHY 3470. IPHY 5580 is restricted to graduate students only.