Idiopathic Hypersomnia

ByRichard J. Schwab, MD, University of Pennsylvania, Division of Sleep Medicine
Reviewed/Revised Jun 2024
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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.

(See also Approach to the Patient With a Sleep or Wakefulness Disorder.)

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

Excessive daytime sleepiness is the main symptom, with difficulty waking up in the morning; 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 narcolepsy1).

Treatment reference

1. Arnulf I, Thomas R, Roy A, Dauvilliers Y: Update on the treatment of idiopathic hypersomnia: Progress, challenges, and expert opinion. Sleep Med Rev. 69:101766. doi: 10.1016/j.smrv.2023.101766. DOI: 10.1016/j.smrv.2023.101766

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