If not treated, people with narcolepsy can fall asleep at any time, such as when at work, while driving and while engaged in a conversation. Narcolepsy is linked to a chemical in the brain called hypocretin, which normally stimulates arousal and helps regulate sleep. Most people with narcolepsy do not produce hypocretin in the deep part of the brain called the hypothalamus. As a result, the body's messages about when to sleep and when to stay awake sometimes occur at the wrong times and places.

Narcolepsy is a lifelong condition that affects an estimated one in 1,000 to 1,500 people. Although it occurs in both men and women, it is slightly more common among men. The condition can begin at any age, although its symptoms usually appear between the ages of 10 and 20. Narcolepsy has been found to be hereditary in some cases.

The hallmark symptom of narcolepsy is an excessive daytime sleepiness (EDS), in which a person falls asleep at times when they want to be awake. EDS may include daytime sleep attacks that occur with or without warning, persistent drowsiness and fleeting moments of sleep that occur in between a person's waking state.

Other symptoms may include:

  • Cataplexy — Most people with narcolepsy experience some degree of cataplexy, which is defined as a sudden loss of voluntary muscle control. An attack may involve only a slight feeling of weakness and limp muscles — such as sagging facial muscles, nodding head, buckling knees, loss of arm strength and garbled speech — or also may cause immediate total body collapse.

    These attacks are usually triggered by intense emotions, such as laughter, surprise, anger, stress and fear, and can last anywhere from a few seconds to thirty minutes.
  • Show More

To diagnose narcolepsy, your doctor will conduct a physical examination and ask about your medical history and symptoms. In addition, a number of tests are available to assist the diagnosis of narcolepsy:

  • Polysomnogram — These tests, performed in an overnight sleep laboratory, measure brain waves and body movements as well as your nerve and muscle function.
  • Multiple Sleep Latency Test (MSLT) — This test measures the time it takes you to fall asleep and move into a deep sleep while taking several naps over a period of time.
  • Genetic Blood Tests — These tests check for specific antigens often found in people who have a genetic predisposition to narcolepsy.

Treatment for narcolepsy typically involves medications to increase daytime alertness and reduce cataplexy and other symptoms. Stimulants are usually prescribed to improve alertness. Antidepressants as well as a new drug called gammahydroxybutyrate, or Xyrem, may be used to control cataplexy, hypnagogic hallucinations and sleep paralysis.


Common stimulants include the following:

  • Dextroamphetamine sulfate, or Dexedrine
  • Methylphenidate hydrochloride, or Ritalin
  • Pemoline, or Cylert
  • Modafinil, or Provigil

There are a few common side effects of stimulants that you may experience when taking these medications. They include headache, irritability, nervousness, insomnia, irregular heartbeat and mood changes.

Show More

Learn More

UCSF Research & Clinical Trials

Other Resources


Reviewed by health care specialists at UCSF Medical Center.

Related Information

UCSF Clinics & Centers


Sleep Disorders Center
2330 Post St., Suite 420
San Francisco, CA 94115
Phone: (415) 885-7886
Fax: (415) 885-3650
Appointment information