Narcolepsy

What is Narcolepsy?

Narcolepsy is a sleep disorder resulting in excessive daytime sleepiness. It is often associated with cataplexy. Cataplexy is characterized by sudden emotionally-induced loss of bilateral muscle tone. In many narcoleptics, laughter can provoke an episode of cataplexy. An episode of cataplexy lasts several seconds to several minutes, and often affects the knees, face, or neck.

How is Narcolepsy Diagnosed?

 After a history and physical by a sleep physician, further sleep testing is usually required to make a diagnosis of narcolepsy. The key test in the diagnosis of narcolepsy is the multiple sleep latency test (MSLT). This test involves a series of 4-5 nap opportunities during the day. By measuring brain wave activity (EEG), this test measures how long it takes a person to fall asleep, and if a person enters REM sleep (dream sleep) during a nap. During the MSLT, narcoleptics will typically fall asleep within 5 to 8 minutes and enter into REM sleep during at least 2 of the naps. The MSLT can be a difficult test to properly administer and interpret; significant experience on the part of the sleep physician and technical staff is necessary. For more technical information about the proper administration of the MSLT, please see Dr. Rack’s recent comments in The American Journal of Psychiatry (http://ajp.psychiatryonline.org/cgi/content/full/162/11/2198-a).

What Causes Narcolepsy?

 Recent research suggests that narcolepsy is an autoimmune disorder. More specifically, narcolepsy is thought to be caused by autoimmune destruction of hypocretin neurons in the hypothalamus (the hypothalamus is an area at the base of the brain important in the regulation of sleep and wakefulness).

 How is Narcolepsy Treated?

 Sleepiness is usually treated with stimulants (such as Ritalin) or Provigil. Many antidepressants help with cataplexy. Xyrem is helpful for both sleepiness and cataplexy. Behavioral methods, especially brief naps, are also useful in the treatment of narcolepsy.

Where can I find out more information?

 Dr. Rack has written extensively about narcolepsy and its treatment in his blog, sleepdoctor (http://sleepdoctor.blogspot.com/). Much of this information is located at http://sleepdoctor.blogspot.com/2005/05/narcolepsy-3.html.

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