Central Disorders of Hypersomnolence

Narcolepsy

Type 1

Background

Narcolepsy with cataplexy, called narcolepsy type 1 (NT1), is characterized by excessive daytime sleepiness, specific findings on MSLT and polysomnography, and low to absent levels of hypocretin in cerebrospinal fluid (CSF). People with NT1 often have refreshing daytime naps, sleep paralysis, hypnagogic or hypnopompic hallucinations, and disturbed nighttime sleep. 

Epidemiology

An early study of the prevalence of narcolepsy in a single county in Minnesota found the prevalence of narcolepsy to be 56.3 per 100,000 people.1 A study of medical and prescription claims in 2016 found the rate of narcolepsy to be about 44.3 per 100,000 people.2 The results of a study in Germany, published in 2022, using a large research database identified a prevalence of diagnosed narcolepsy at slightly lower, at 17.88 per 100,000 people.3 A study using a very large database in the United States discovered a prevalence of diagnosed NT1 of 14 per 100,000 people.4

Diagnosis

The diagnosis of NT1 requires that both of the following criteria be met.5

  • The person has daily periods of uncontrollable sleepiness or falling asleep that have lasted for at least 3 months.
  • The patient has either or both of the following:
  • Cataplexy and the results of a standard Multiple Sleep Latency Test (MSLT) that indicate a mean sleep latency of 8 minutes of less and at least 2 sleep-onset rapid eye movement periods (SOREMPs). One SOREMP on polysomnography can substitute for 1 of the 2 SOREMPs on MSLT.
  • The hypocretin level in the cerebrospinal fluid (CSF) is either less than 110 pg/mL or is less than one-third of the normal value using the same standardized assay.

Narcolepsy affects about 1 in 2,000 people in the United States and Western Europe—3 million people worldwide

Type 2

Background

Narcolepsy without cataplexy, called narcolepsy type 2 (NT2), is characterized by excessive daytime sleepiness, specific findings on MSLT and polysomnography, and normal levels of hypocretin in CSF. People with NT2 often have refreshing daytime naps, sleep paralysis, hypnagogic or hypnopompic hallucinations, and disturbed nighttime sleep.

Epidemiology

An early study of the prevalence of narcolepsy in a single county in Minnesota found the prevalence of narcolepsy to be 56.3 per 100,000 people.1 A study of medical and prescription claims in 2016 found the rate of narcolepsy to be about 44.3 per 100,000 people.2 A study in Germany using a large research database found the prevalence of diagnosed narcolepsy to be slightly lower, at 17.88 per 100,000 people.3 A study using a very large health claims database in the United States discovered a prevalence of diagnosed NT1 of 65.4 per 100,000 people.4

Diagnosis

A diagnosis of NT2 requires that the following 5 criteria be met.5

  • The person has daily periods of uncontrollable sleepiness or falling asleep that have lasted for at least 3 months.
  • A standard MSLT reveals a mean sleep latency of 8 minutes of less and at least 2 SOREMPs. One SOREMP on polysomnography can substitute for 1 of the 2 SOREMPs on MSLT.
  • A standard MS The person does not have cataplexy. LT reveals a mean sleep latency of 8 minutes of less and at least 2 SOREMPs. One SOREMP on polysomnography can substitute for 1 of the 2 SOREMPs on MSLT.
  • The person’s hypocretin level in the CSF has either not been measured or is greater than than 110 pg/mL or greater than one-third of the normal value using the same standardized assay.
  • No drug or medication, insufficient sleep, obstructive sleep apnea, or delayed sleep phase disorder better explains the sleepiness or findings on MSLT.
Idiopathic hypersomnia

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.