Narcolepsy is an uncommon condition in which the sleep-wake regulators in the brain do not function correctly. Because of this, sufferers are excessively sleepy by day and fall asleep at inappropriate times. So-called ‘sleep attacks’ may result from an overwhelming sense of daytime sleepiness.
People who suffer from narcolepsy often also experience episodes of cataplexy, in which there is a dramatic reduction in muscle tone in association with emotional triggers such as laughing, joking, surprise, fear or anger. Depending on the severity, this can cause minor effects such as slurring of speech but in severe cases, complete loss of muscle tone can occur, resulting in the sufferer becoming limp and falling to the ground. Other features of the full narcolepsy/cataplexy syndrome include sleep paralysis, auditory and/or visual hallucinations and automatic behaviour.
Our current understanding of narcolepsy is that it is a form of very selective neurodegeneration triggered by an environmental factor, possbly a virus. Although narcolepsy cannot be cured, both the excessive sleepiness and cataplexy can usually be helped considerably with medications. We have a special narcolepsy clinic at the Woolcock Institute and are involved with work based at Stanford University investigating the immune reactions that lead to narcolepsy.