Central Disorders of Hypersomnolence

Idiopathic Hypersomnia


Idiopathic hypersomnia (IH) is a sleep disorder in which the affected individual has prolonged sleep or daytime sleepiness. About half of people with IH have sleep inertia, during which they have difficulty waking up, frequently return to sleep, are quite irritable, and have automatic behaviors and confusion. Many people with IH have headaches, orthostatic hypotension, difficulty regulating their temperature, and Raynaud syndrome (all symptoms of a disturbance in the autonomic nervous system). Some people may have sleep paralysis or hypnagogic hallucinations.


A study of medical and prescription claims in 2016 found the rate of IH to be about 10 per 100,000 people.2



A diagnosis of IH requires that the following 6 criteria be met.5

1. Silber MH, Krahn LE, Olson EJ, Pankratz VS. The epidemiology of narcolepsy in Olmsted County, Minnesota: a population-based study. Sleep. 2002;25(2):197-202.

2. Acquavella J, Mehra R, Bron M, Suomi JM, Hess GP. Prevalence of narcolepsy and other sleep disorders and frequency of diagnostic tests from 2013-2016 in insured patients actively seeking care. J Clin Sleep Med. 2020;16(8):1255-1263.

3. Kallweit U, Nilius G, Trumper D, Vogelmann T, Schubert T. Prevalence, incidence, and health care utilization of patients with narcolepsy: a population-representative study. J Clin Sleep Med. 2022.

4. Scheer D, Schwartz SW, Parr M, Zgibor J, Sanchez-Anguiano A, Rajaram L. Prevalence and incidence of narcolepsy in a US health care claims database, 2008-2010. Sleep. 2019;42(7).

5. American Academy of Sleep Medicine. International Classification of Sleep Disorders. Darien, IL: American Academy of Sleep Medicine, 3rd ed.; 2014.

6. Liu Y, Wheaton AG, Chapman DP, al. e. Prevalence of healthy sleep duration among adults: United States, 2014. Morbidity and Mortality Weekly. 2016;65(6):137-141.