Physicians in all areas of medicine encounter patients who complain of disturbed sleep. The purpose of this lecture is to provide clinicians with the knowledge needed to recognize and treat major sleep disorders encountered in clinical practice. The course will also review the function of sleep and sleep disorders commonly encountered in clinical practice. The lecture will review assessment and evaluation strategies of excessive sleepiness, sleep-disordered breathing, narcolepsy, chronic insomnia disorder, parasomnias, and abnormal behaviors at night.