Narcolepsy is a chronic neurological condition characterized by pervasive, excessive daytime sleepiness, as well as the abnormal intrusion of rapid eye movement sleep into wakefulness. Narcolepsy type I, or hypocretin deficiency syndrome, also includes cataplexy—a sudden loss of skeletal muscle tone during wakefulness—and is often triggered by a strong emotion, such as laughter, surprise, or anger. Other symptoms of narcolepsy include fragmented or disturbed nighttime sleep, sleep paralysis, and hallucinations, either when falling asleep (hypnagogic) or when waking up (hypnopompic). The evaluation of people with suspected narcolepsy requires meticulous clinical history taking, validating the patient’s sleep duration and regularity, and assessment of patients for conditions that could also present with hypersomnia, such as insufficient sleep and delayed sleep phase disorder, depression, and obstructive sleep apnea. Management of people for narcolepsy includes lifestyle modification, short and strategic shift power naps, and pharmacologic agents to improve daytime sleepiness, episodes of cataplexy, and sleep fragmentation at night. The lecture will review all aspects of narcolepsy, defining its unique features, differential diagnosis, and strategies for evaluation, management, and patient advocacy.