What is IH?
What is Idiopathic Hypersomnia?
Idiopathic hypersomnia (IH) is a chronic neurological disorder that results in daytime sleepiness.
It is an uncommon disorder that causes patients to be sleepy during the day even after a full night of sleep. It can also cause difficulty waking up in the morning, and if a patient takes a nap during the day, he or she generally doesn’t feel refreshed and often wakes up disoriented or confused.
About 1.5% of the US population has IH.1 The word “idiopathic” means the cause is unknown. However, certain things can trigger IH, including abrupt change in sleep-wake habits, overexertion, general anesthesia, viral illness, and mild head trauma.2
The strong need for sleep in a patient with IH can occur any time, including when the patient is at work, driving a car, or at home relaxing. As a result, IH can be dangerous and needs medical attention. Diagnosing IH requires a careful examination by a doctor or other caregiver, and the aim of treatment is to control symptoms either through medication or non-medication strategies.
References
- Plante DT, Hagen EW, Barnet JH, Mignot E, Peppard PE. Prevalence and course of idiopathic hypersomnia in the Wisconsin Sleep Cohort study. Neurology. 2024;102:e207994. doi:10.1212/WNL.0000000000207994
Dhillon K, Sankari A. Idiopathic hypersomnia [updated 7/31/2023]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025.
All URLs accessed September 2, 2025.
