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Idiopathic Hypersomnia


Richard J. Schwab

, MD, University of Pennsylvania, Division of Sleep Medicine

Reviewed/Revised May 2022 | Modified Sep 2022
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Idiopathic hypersomnia is excessive daytime sleepiness with or without a long sleep time; it is differentiated from narcolepsy by lack of cataplexy, hypnagogic hallucinations, and sleep paralysis.

Idiopathic hypersomnia is not well-characterized. Cause is presumed to be dysfunction of the central nervous system.

Excessive daytime sleepiness is the main symptom; sleep time may or may not be prolonged.

Diagnosis of Idiopathic Hypersomnia

  • History or sleep logs

  • Sleep tests

In idiopathic hypersomnia with a long sleep time, the history or sleep logs indicate > 10 hours of nocturnal sleep; in idiopathic hypersomnia without a long sleep time, it is > 6 hours but < 10 hours. In both cases, polysomnography shows no evidence of other sleep abnormalities. Multiple sleep latency testing shows short sleep latencies (< 8 minutes) with fewer than 2 REM periods. Typically, patients with idiopathic hypersomnia have difficulty waking up, and when they awaken, they experience a period of sleep inertia characterized by drowsiness, decreased cognition, and motor impairment.

Treatment of Idiopathic Hypersomnia

  • Similar to that of narcolepsy

Treatment of idiopathic hypersomnia is similar to that of narcolepsy Treatment Narcolepsy is characterized by chronic excessive daytime sleepiness, often with sudden loss of muscle tone (cataplexy). Other symptoms include sleep paralysis and hypnagogic and hypnopompic... read more ; ie, it is treated with wake-promoting drugs (eg, modafinil; sodium oxybate; a combination drug that contains calcium, magnesium, potassium, and sodium oxybates Treatment ).

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