DIAGNOSING IH

Idiopathic Hypersomnia (IH) is a unique, multi-symptom medical condition that is different  from other disorders

The International Classification of Sleep Disorders, 3RD EDITION, TEXT REVISION (ICSD-III-TR)

The ICSD-III-TR helps objectively diagnose patients and provides more information for developing an appropriate treatment plan. For a diagnosis of IH, the following must be met1:

ICD-10-CM codes2: G47.11 (with long sleep), G47.12 (without long sleep)

Excessive daytime sleepiness () daily for ≥3 months1

is not present1

and findings are not consistent with a diagnosis of narcolepsy type 1 or 21

Insufficient sleep syndrome is ruled out1

At least one of the following:1

  • shows a mean sleep latency of ≤8 minutes
  • Total 24-hour sleep time is ≥660 minutes (typically 12-14 hours) on 24-hour monitoring (performed after correction of chronic sleep deprivation), or by wrist actigraphy in association with a sleep log (averaged over at least 7 days with unrestricted sleep)

Symptoms and signs are not better explained by a circadian rhythm sleep-wake disorder or other current sleep disorder, medical disorder, mental disorder, or medication/substance use or withdrawal1

Additional supportive clinical features include1:

Severe and prolonged
 
Long, unrefreshing naps (>1 hour)

IH IS THOUGHT TO BE UNDERDIAGNOSED

In the US, approximately 37,000 adult patients have been diagnosed with IH and are actively seeking medical care. It is estimated that far fewer people are currently receiving pharmacological treatment for their IH. This low number of people may be due to the many difficulties in identifying and diagnosing IH, as well as distinguishing it from other similar sleep disorders.3

Assessing symptoms and diagnosing Idiopathic Hypersomnia

Download IH Guide

Knowing the key symptoms and utilizing sleep testing can increase confidence in the diagnosis AND TREATMENT of IH

Assess symptoms

is an essential feature of IH1

  • Understanding key symptoms and other aspects of medical history is crucial when evaluating patients who present with

In addition to , patients with IH commonly report experiencing other debilitating symptoms from morning to night. These include:

Profound sleep inertia

Prolonged difficulty waking up, with repeated returns to sleep1

Ask your patient: Is it extremely difficult for you, or even impossible, to wake up in the morning without several alarm calls or the help of someone close?4

Long unrefreshing naps

Of the patients who do nap during the day, the majority report taking naps longer than 60 minutes and many do not find them to be restorative1,5

Ask your patient: Do you feel refreshed after you nap?4

Prolonged sleep time

≥11 hours total sleep time per 24 hours1

Ask your patient: If you had no obligations or commitments to consider, how long would you prefer to sleep at night?4

Cognitive impairment

Attention deficits, difficulty concentrating, memory loss6,7

Ask your patient: Is it hard for you to sustain focus or remember things?2,7

Initiate Sleep Testing

If no clear cause of sleepiness is found or sleepiness persists after correction of other factors, sleep testing with polysomnography () and multiple sleep latency test () should be considered.

PSG

A sleep test that records sleep stages and physiologic parameters1,8

is important in the workup of patients with possible IH and is used to exclude other causes of 1

MSLT

A series of five 20-minute naps at 2-hour intervals that measure how quickly a patient falls asleep and the number of SOREMPs9

If a patient has an ≤8 min and <2 on the , consider a diagnosis of IH1

“Getting a diagnosis was a relief. I was like, oh my gosh, I finally know what is wrong with me. There's actually really something diagnosable that's wrong with me.”

—Patient living with IH

Want to see how the 5 key IH symptoms can overlap with other conditions?

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References
  1. American Academy of Sleep Medicine. International Classification of Sleep Disorders. 3rd ed, Text Revision. Darien, IL: American Academy of Sleep Medicine; 2023.
  2. ICD-10-CM tabular list of diseases and injuries. Centers for Medicare & Medicaid Services website. Updated February 1, 2024. Accessed June 4, 2024. https://www.cms.gov/medicare/coding-billing/icd-10-codes/2024-icd-10-cm
  3. Data on File (XYW-2021-025-28). Jazz Pharmaceuticals, Inc.
  4. Dauvilliers Y. Idiopathic hypersomnia severity scale. 2018. Accessed June 4, 2024. http://links.lww.com/WNL/A854.
  5. Arnulf I, Leu-Semenescu S, Dodet P. Precision medicine for idiopathic hypersomnia. Sleep Med Clin. 2019;14(3):333-350.
  6. 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.
  7. 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.
  8. Rundo, JV, Downey R. Polysomnography. In: Handbook of Clinical Neurology. Vol 160. Elsevier; 2019:381-392.
  9. Littner MR, Kushida C, Wise M. Practice Parameters for Clinical Use of the Multiple Sleep Latency Test and the Maintenance of Wakefulness Test: An American Academy of Sleep Medicine Report. Sleep: 2005;28(1):113-121.