Narcolepsy causes sleepiness not due to sleep deprivation, poor sleep quality, or sleep apnea.
Narcolepsy type 1 is caused by damage to a certain part of the brain (the hypothalamus), resulting in decreased production of orexin, a hormone that helps maintain wakefulness. Narcolepsy type 2 does not have low levels of orexin, and its cause is unknown.
Signs and Symptoms of Narcolepsy
Narcolepsy causes excessive daytime sleepiness; patients fall asleep frequently and involuntarily while sitting still or during other activities. Although patients with narcolepsy typically feel well rested after a brief nap, sleepiness recurs within a few hours.
Most patients with narcolepsy also have abnormal rapid eye movement (REM) sleep, the period during which people have dreams. While REM sleep normally occurs only in the middle of the night, in narcolepsy, it occurs during the daytime or at sleep onset. Narcolepsy is also associated with vivid dreams, hallucinations when falling asleep, disrupted nighttime sleeping, and sleep paralysis, which is a temporary inability to move soon after falling asleep or awakening from sleep.
Cataplexy, which involves a sudden, brief episode of muscle weakness, is experienced by patients with narcolepsy type 1 but does not occur in narcolepsy type 2. Cataplexy is triggered by strong and usually positive emotions, such as joking or laughing, and causes temporary weakness or paralysis of muscles in the face, neck, arms, and legs. In severe cases, cataplexy causes patients to collapse and have wakeful paralysis lasting up to 1 to 2 minutes.
Who Is Affected by Narcolepsy?
Narcolepsy affects 25 to 50 people per 100 000 worldwide. Symptoms typically start at age 7 to 25 years; however, the diagnosis is often made years or decades after onset of symptoms.
What Other Conditions Are Associated With Narcolepsy?
Narcolepsy is associated with obesity, early puberty (if onset is in childhood), depression, and decreased quality of life. Without treatment, patients with narcolepsy may lose self-esteem and have difficulty attending school or work.
How Is Narcolepsy Typically Diagnosed?
Narcolepsy is diagnosed based on results of an overnight sleep recording and a multiple sleep latency test (MSLT). In an MSLT, patients are instructed to try to fall asleep during five 20-minute daytime nap opportunities that occur every 2 hours over the course of 1 day. Narcolepsy is diagnosed by an MSLT if a patient falls asleep quickly and has REM sleep in 2 or more of the 5 daytime naps. In some cases, narcolepsy is diagnosed based on low orexin levels in cerebrospinal fluid.
Treatments for Narcolepsy
Medications to treat excessive daytime sleepiness and cataplexy in adults with narcolepsy include sodium oxybate and pitolisant. Modafinil, armodafinil, and solriamfetol are recommended treatments for excessive sleepiness, and moderate to high doses of amphetamines or methylphenidate are also commonly used. Antidepressants such as fluoxetine or venlafaxine may be considered for cataplexy and disturbed REM sleep. Drugs that replace orexin are being studied in clinical trials.
Behavioral strategies, including scheduled naps, an established sleep time, a balanced diet, and regular exercise, are recommended. Cognitive behavior therapy, counseling, and peer-centered group therapy may also be helpful.
Box Section Ref ID
Published Online: May 5, 2023. doi:10.1001/jama.2023.5149
Conflict of Interest Disclosures: None reported.
Sources: Mahoney CE, Cogswell A, Koralnik IJ, Scammell TE. The neurobiological basis of narcolepsy. Nat Rev Neurosci. 2019;20(2):83-93. doi:10.1038/s41583-018-0097-x
Franceschini C, Pizza F, Cavalli F, Plazzi G. A practical guide to the pharmacological and behavioral therapy of narcolepsy. Neurotherapeutics. 2021;18(1):6-19. doi:10.1007/s13311-021-01051-4