brain, spinal cord, and nerve disorders
Narcolepsy
Introduction
Narcolepsy is a sleep disorder marked by excessive sleepiness during the day or recurring, uncontrollable episodes of sleep during normal waking hours, usually with sudden, temporary episodes of muscle weakness (cataplexy). Other symptoms include sleep paralysis, vivid dreams, and hallucinations while falling asleep or waking up from sleep. Testing in a sleep laboratory, with polysomnography and multiple sleep latency testing, is needed to confirm the diagnosis. Drugs may be used to help keep people awake and to control other symptoms. (See also Overview of Sleep .) Narcolepsy occurs in about 1 of 2,000 people in the United States, Europe, and Japan. It is equally common among men and women. What causes narcolepsy is unknown. Some people with narcolepsy have a similar group of genes, but the cause is not thought to be genetic. Environmental factors seem to be involved and may trigger the disorder. Some evidence suggests that narcolepsy may be caused by an autoimmune reaction that destroys nerve cells in a certain area of the brain. (An Autoimmune Disorders occurs when the immune system attacks the body's own tissues.) People with narcolepsy sleep a lot during the day. As a result, narcolepsy can be disabling and increases the risk of motor vehicle and other accidents. Narcolepsy persists throughout life but does not affect life expectancy. Narcolepsy reflects, in part, abnormalities in the timing and control of rapid eye movement (REM) sleep. Many symptoms resemble what happens during REM sleep. The muscle weakness, sleep paralysis, and hallucinations of narcolepsy resemble the loss of muscle tone, paralysis, and vivid dreaming that occur during REM sleep. like narcolepsy, results in excessive daytime sleepiness. Typically, people with this disorder have trouble waking up, and when they wake up, they feel drowsy, mentally foggy, and as if they cannot move (called sleep inertia). Diagnosis and a 