Overview

Idiopathic hypersomnia is a condition that causes people to be very sleepy during the day even after a full night of sleep. People with the condition have trouble waking up from sleep. They also may wake up confused and disoriented. Naps typically don't lead to feeling refreshed.

Idiopathic hypersomnia is not common, and the cause of the condition is not known.

The need to sleep can strike at any time, including when driving a car or working. This makes idiopathic hypersomnia potentially dangerous.

The condition often develops slowly over time. Diagnosing idiopathic hypersomnia requires ruling out more common sleep conditions. Treatment aims to control symptoms with medicine.

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Symptoms

The main symptom of idiopathic hypersomnia is being very sleepy during the day. Symptoms begin slowly over several weeks or months and may include:

Having a strong need to sleep.
Not being able to stay awake and alert during the day.
Sleeping more than 11 hours at night.
Having trouble waking up in the morning.
Being confused, moving slowly and having trouble with coordination after waking up.
Feeling anxiety after waking up.

People with idiopathic hypersomnia may need to set several loud alarms to wake up in the morning.

People with the condition also may:

Take naps longer than an hour.
Not feel refreshed after naps.
Have trouble with memory and attention.

Rarely, idiopathic hypersomnia can cause someone to fall asleep suddenly during the day.

Some people with idiopathic hypersomnia may experience automatic behavior when they are very sleepy. This can include staring, or they may drive without purpose and later realize that they are miles from home. Automatic behavior also may include writing or saying things that don't make sense. Afterward, people with idiopathic hypersomnia don't remember the behavior.

Causes

The cause of idiopathic hypersomnia is not known.

Risk factors

Experts don't know what causes idiopathic hypersomnia, so risk factors are not known. But symptoms usually appear at a younger age, between ages 10 and 30. And women may be more likely to have idiopathic hypersomnia than are men.

By Mayo Clinic Staff

Idiopathic hypersomnia care at Mayo Clinic

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Diagnosis & treatment

Oct. 30, 2024

Chervin RD. Idiopathic hypersomnia. https://www.uptodate.com/contents/search. Accessed May 12,2022.
Idiopathic hypersomnia. Genetic and Rare Diseases Information Center. https://rarediseases.info.nih.gov/diseases/8737/idiopathic-hypersomnia. Accessed May 12, 2022.
Trotti LM, et al. Idiopathic hypersomnia and other hypersomnia syndromes. Neurotherapeutics.2021; doi:10.1007/s13311-020-00919-1.
Dauvilliers Y, et al. Safety and efficacy of lower-sodium oxybate in adults with idiopathic hypersomnia: A phase 3, placebo-controlled, double-blind, randomized withdrawal study. Lancet Neurology. 2022; doi:10.1016/S1474-4422(21)00368-9.
Littner MR, et al. Practice parameters for clinical use of the multiple sleep latency test and the maintenance of wakefulness test. Sleep. 2005; doi:10.1093/sleep/28.1.113.
Inoue Y, et al. Efficacy and safety of modafinil in patients with idiopathic hypersomnia without long sleep time: A multicenter, randomized, double-blind, placebo-controlled, parallel-group comparison study. Sleep. 2021; doi:10.1016/j.sleep.2021.01.018.
Sowa NA. Idiopathic hypersomnia and hypersomnolence disorder: A systematic review of the literature. Psychosomatics. 2016; doi:10.1016/j.psym.2015.12.006.
Saini P, et al. Hypersomnia evaluation, treatment and social and economic aspects. Sleep Medicine Clinics. 2017; doi:10.1016/j.jsmc.2016.10.013.
Nguyen H. AllScripts EPSi. Mayo Clinic. April 20, 2022.
Maski K, et al. Treatment of central disorders of hypersomnolence: An American Academy of Sleep Medicine clinical practice guideline. Journal of Clinical Sleep Medicine. 2021; doi:10.5664/jcsm.9328.

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