The complaint of excessive daytime sleepiness (EDS) is associated with a number of disorders. The frequently disabling symptoms of EDS are just beginning to be addressed. This article offers nurse practitioners background information to help in evaluating EDS symptoms. Disorders related to the physiological need for sleep and the response to disrupted sleep or the effect of psychobiological sleep disruption are presented. Differential diagnoses are reviewed and keys to case management are offered. The management of sleep disorders may involve a collaborative role with other health professionals in order to provide optimal patient care. To assist the NP in referring the patient to specialized care, referral services are described.