Definition

Narcolepsy is a disorder of the nervous system. It results in frequent, involuntary episodes of sleep during the day. Sleep attacks can occur while you drive, talk, or work.

Causes

The cause is unknown. It is thought to have a genetic link. There is increasing evidence that it may be an autoimmune disorder. In this type of disorder, the body’s own immune system attacks a part of the brain.

Risk Factors

Having family members with narcolepsy is a risk factor for the condition.

Symptoms

Symptoms usually start during the teenage years. Onset may range from 5-50 years old. Symptoms may worsen with age. They 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
• Temporary paralysis while awakening or falling asleep
• Frightening mental images that appear while awakening or as one falls asleep
• Memory problems
• Symptoms may be triggered by:
  • A monotonous environment
  • A warm environment
  • Eating a large meal
  • Strong emotions

Diagnosis

You will be asked about your symptoms and medical history. A physical exam will be done. 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 (REM) sleep, which occurs earlier than normal in narcolepsy
• General sleep lab study—often done the night before an MSLT; helps to rule out other causes of daytime sleepiness by monitoring:
  • 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
• A questionnaire regarding your degree of daytime sleepiness

Treatment

Treatment may include:

• Stimulant medications that increase levels of daytime alertness
• Antidepressants to help treat symptoms of narcolepsy

Other treatment options include:

• Planned short naps throughout the day
• Counseling to cope with issues of self esteem
• Wearing medical alert jewelry

Prevention

There are no guidelines to prevent narcolepsy. But, you can try to prevent symptoms by:

• Exercising on a regular basis
• Getting enough sleep at night

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

Health Canada http://www.hc-sc.gc.ca

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

Feldman NT. Narcolepsy. Southern Medical Journal. 2003;96:277-282.

Narcolepsy. EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed
Updated November 18, 2014. Accessed June 3, 2015.

Narcolepsy fact sheet. National Heart, Lung, and Blood Institute. National Institutes of Health website. Available at:
http://www.ninds.nih.gov/disorders/narcolepsy/detail_narcolepsy.htm
Updated January 5, 2015. Accessed June 3, 2015.

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