Narcolepsy

Definition

Narcolepsy, which affects approximately 140,000 Americans, is a neurologic disorder characterized by frequent, involuntary, episodes of sleeping during the day. Sleep attacks may occur while driving, talking, or working.

Causes

The cause of narcolepsy is unknown, but it is thought to have a genetic component. There is increasing evidence that it may be an autoimmune disorder in which the body’s own immune system attacks a very specific part of the brain.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

  • Family members with narcolepsy

Symptoms

Symptoms of narcolepsy usually start during the teenage years. Onset may range from 5 to 50 years old. Symptoms may worsen with aging, but may improve in women after menopause.

Symptoms include:

  • Excessive daytime sleepiness
  • Daytime involuntary sleep attacks
  • Unrefreshing sleep
  • Sudden loss of muscle tone without loss of consciousness (cataplexy)
  • Temporary paralysis while awakening
  • Frightening mental images that appear as one falls asleep
  • Memory problems
  • Symptoms may be triggered by:
    • A monotonous environment
    • A warm environment
    • Eating a large meal
    • Strong emotions

Brainstem—Area of Brain Related to Alertness

GM00010_97870_brainstem.jpg

© 2008 Nucleus Medical Art, Inc.

Diagnosis

The doctor will ask about your symptoms and medical history, and perform a physical exam. If narcolepsy is suspected, you may be referred to a specialist in sleep disorders.

Tests may include:

  • Multiple sleep latency test (MSLT)— measures the onset of rapid eye movement sleep, which occurs earlier than normal in narcolepsy
  • General sleep lab study—helps rule out other causes of daytime sleepiness. It is often performed the night before an MSLT. The following things are monitored while you sleep:
    • Brain waves
    • Eye movements
    • Muscle activity
    • Respiration
    • Heart beat
    • Blood oxygen levels
    • Total nighttime sleep
    • Amount of nighttime REM sleep
    • Time of onset of REM sleep
    • Degree of daytime sleepiness

Treatment

Treatment may include:

  • Stimulant medications that increase levels of daytime alertness include:
    • Methylphenidate
    • Pemoline (requires regular blood testing for liver function)
    • Dextroamphetamine
    • Methamphetamine
    • Modafinil
  • Antidepressants—to help treat many symptoms of narcolepsy, include:
    • Cataplexy
    • Hallucinations
    • Sleep paralysis
  • Other treatment options include:
    • Planned short naps throughout the day
    • Counseling to cope with issues of self esteem
    • Wearing a medical alert bracelet or pendant

Prevention

There are no guidelines for preventing narcolepsy itself. However, you can try to prevent symptoms.

  • Avoid activities that carry a risk of injury from a sudden sleep attack, such as:
    • Driving
    • Climbing ladders
    • Using dangerous machinery
  • Exercise on a regular basis.
  • Get adequate sleep at night.

RESOURCES:

Narcolepsy Network
http://www.narcolepsynetwork.org

National Sleep Foundation
http://www.sleepfoundation.org

CANADIAN RESOURCES:

BC HealthGuide
www.bchealthguide.org

Better Sleep Council of Canada
www.bettersleep.ca

References:

Dauvilliers Y, Arnulf I, Mignot E. Narcolepsy with cataplexy. Lancet . 2007;369:499-511.

Feldman NT. Narcolepsy. Southern Medical Journal . 2003;96:277-82.

Narcolepsy: new understanding of irresistible sleep. Mayo Clinic Proceedings . 2001.

National Institute of Neurological Disorders and Stroke, National Institutes of Health



Last reviewed January 2008 by Rimas Lukas, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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