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Idiopathic hypersomnia

Ronald D Chervin, MD, MS
Section Editor
Thomas E Scammell, MD
Deputy Editor
April F Eichler, MD, MPH


Idiopathic hypersomnia is a sleep disorder that is characterized by chronic excessive daytime sleepiness (daily periods of irrepressible need to sleep or daytime lapses into sleep) and often difficulty waking up from nocturnal sleep or daytime naps. The condition is categorized as a central disorder of hypersomnolence; other sleep disorders in this category include narcolepsy type 1 and type 2 and Kleine-Levin syndrome (recurrent hypersomnia) [1].

The pathophysiology of idiopathic hypersomnia is not well understood, and diagnosis requires exclusion of other more common causes of excessive sleepiness. When a diagnosis of idiopathic hypersomnia is established, treatment is largely pharmacologic and aimed at control of symptoms, with generally good, but somewhat variable results.

This topic will discuss the epidemiology, clinical features, diagnosis, and treatment of idiopathic hypersomnia. An approach to the patient with excessive daytime sleepiness is presented separately. (See "Approach to the patient with excessive daytime sleepiness".)


The prevalence of idiopathic hypersomnia in the general population is unknown [2], in part because laboratory-based polysomnography and other assessments that would be necessary to rule out other causes of excessive daytime sleepiness have not been feasible in large numbers of unselected, representative subjects from the community. Based largely on sleep center referrals, idiopathic hypersomnia appears to be one-tenth to one-half as common as narcolepsy, suggesting a prevalence of approximately 20 to 50 cases per million [3-6]. There is no clear gender association.

The onset of idiopathic hypersomnia typically occurs between 10 and 30 years of age. In a series of 77 patients, the mean age of symptom onset was 17 and the mean age of diagnosis was 30 [3].

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Literature review current through: Nov 2017. | This topic last updated: Mar 14, 2017.
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