Narcolepsy is a disorder involving a chemical imbalance in the brain cells that control wakefulness and sleep. The disorder can run in families or appear as an isolated problem affecting only one individual in a family. Narcolepsy, after sleep apnea, is the second most common cause of disabling daytime sleepiness. Narcolepsy affects about 1 of every 2000 people throughout the world, is even about as common as multiple sclerosis.
The patient suffers from excessive daytime sleepiness, with the possibility of a "sleep attack" -- at mealtime, at the theater -- really anywhere. The patient can often fight this sleepiness for awhile but eventually the sleepiness is overwhelming. A short nap may restore wakefulness temporarily.
Narcolepsy involves the abnormal intrusion of part or all of rapid eye movement or dream sleep (REM sleep) into wakefulness. Narcoleptic paralysis is involuntary and can come under two circumstances: (a) cataplexy -- sudden muscle weakness leading to partial or complete collapse precipitated by excitement or an emotional response, most frequently laughter.(b) sleep paralysis -- an often frightening inability to move just before falling asleep or upon awakening.
The hallucinations of narcolepsy are known as hypnagogic and hypnopompic hallucinations. These hallucinations also depend on REM sleep mechanisms and come as sometimes benign, sometimes terrifying apparitions just as the narcoleptic falls asleep or just as they are awakening.
Current research indicates that the gene which produces the specific HLA-DQ antigen called, HLA-DQB*0602, seems to be a true narcolepsy susceptibility gene. However, about 20 - 30 percent of the population have this gene and only about 0.05 percent of the population have narcolepsy. This means that other genes or environmental factors are necessary for narcolepsy to develop in people with the HLA-BQB*0602 gene.
There is no cure, as yet, for narcolepsy. The symptoms are controlled with a 'double barreled' approach: (a) Several daytime naps and stimulants, such as amphetamines, control the abnormal tendency to fall asleep at inappropriate times; (b) Other drugs that suppress REM sleep such as antidepressants, help control the symptoms of cataplexy, sleep paralysis and hypnagogic hallucinations.
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