Skip to main content

What is IH?

Idiopathic Hypersomnia (IH) is a multi-symptom sleep disorder

Despite sleeping a normal (or longer than normal) amount of time each night, people with IH may still experience debilitating symptoms during the day1

Jump to:

What are the 5 key symptoms of IH?

  • EDS

    Prevalence: 100%1

    The inability to stay awake and alert during the day, resulting in periods of irrepressible need for sleep or unintended lapses into drowsiness or sleep.1,2

  • Profound Sleep inertia or “sleep drunkenness”

    Estimated prevalence: 36-66%1

    Characterized by prolonged difficulty waking up, repeated returns to sleep, irritability, automatic behavior, and confusion.1

  • Cognitive impairment or “brain fog”

    Estimated prevalence: 47-79%3*

    Patients with IH are more likely to experience a multitude of cognitive impairments, such as attention deficits, difficulties in concentrating, and memory loss.3,4

  • Long unrefreshing naps

    Estimated prevalence: 46-78%1

    Many patients with IH refrain from napping despite their sleepiness because they do not consider naps refreshing. Of those who do nap during the day, the majority report taking naps longer than 60 minutes.5

  • Prolonged sleep time

    Estimated prevalence: At least 30%1

    As classified by the American Academy of Sleep Medicine, when an individual's total 24-hour sleep time is ≥11 hours.1

*Based on a prospective cohort of 62 patients diagnosed with IH and 50 age- and sex-match controls studied over 4 years and systematically interviewed on subjective symptoms using a standardized questionnaire. Cognitive problems include memory problems, attention deficit, frequently forgetting something, difficulty focusing in a loud environment, and mislaying objects.3

“…living with Idiopathic Hypersomnia is more than just being sleepy. There are all of the cognitive connections. And for me that's some of the most challenging things.”
—Patient living with IH

What are some other symptoms of IH?

People living with IH may also experience symptoms associated with autonomic dysfunction1,3:

  • Headache
  • Temperature dysregulation
  • Palpitations
  • Digestive problems

During periods of drowsiness, people living with IH may exhibit automatic behaviors that are performed without conscious self-control, such as3,6:

  • Driving miles away from home
  • Forgetting to pick up children from school
  • Putting clothes in the dishwasher

Patients may not even be aware of these episodes unless a witness points them out.

Watch video

Beth talks about living with IH and what motivated her to seek help—even after getting what she felt was “good” sleep.

Looking for tools to help you confirm an IH diagnosis?

Find diagnosis tools


  1. American Academy of Sleep Medicine. International Classification of Sleep Disorders. 3rd ed. Darien, IL: American Academy of Sleep Medicine; 2014.
  2. Khan Z, Trotti LM. Central disorders of hypersomnolence: focus on the narcolepsies and idiopathic hypersomnia. Chest. 2015;148(1):262-273.
  3. Vernet C, Leu-Semenescu S, Buzare MA, Arnulf I. Subjective symptoms in idiopathic hypersomnia: beyond excessive sleepiness. J Sleep Res. 2010;19(4):525-534.
  4. Trotti LM, Ong JC, Plante DT, Murray CF, King R, Bliwise DL. Disease symptomatology and response to treatment in people with idiopathic hypersomnia: initial data from the Hypersomnia Foundation registry. Sleep Med. 2020;75:343-349.
  5. Arnulf I, Leu-Semenescu S, Dodet P. Precision medicine for idiopathic hypersomnia. Sleep Med Clin. 2019;14(3):333-350.
  6. Masri TJ, Gonzales CG, Kushida CA. Idiopathic hypersomnia. Sleep Med Clin. 2012;283-289.

This site is intended for US healthcare professionals only.

© 2023 Jazz Pharmaceuticals plc US-SLE-2200201 Rev1023

Help patients with IH find you

Join The Hypersomnia Foundation
International HCP Directory