Perhaps one of the most famous and disturbing sleep disorders is narcolepsy — the condition in which a seemingly fully alert person suddenly and without warning becomes drowsy and falls asleep. Narcolepsy, which occurs in approximately 1 in 2000 Americans, causes excessive daytime sleepiness.
The disorder involves abnormal onset of REM sleep. Rather than progressing through a series of sleep stages, persons suffering from narcolepsy involuntarily fall into dream sleep at any time. Narcolepsy may appear in several forms: sleep attacks, cataplexy, paralysis, hallucinations or fragmented night-time sleep. In a sleep attack, a person may suddenly fall asleep during the course of their normal daytime activities. They can even begin to speak appropriate to their dream sequence.
While the cause of narcolepsy is not completely understood, current research points to a combination of genetic and environmental factors that influence the immune system.
Signs and symptoms of narcolepsy include excessive daytime sleepiness, micro-naps, abnormal REM sleep and REM intrusion into daytime wakefulness, muscle weakness when angry or laughing, sleep paralysis, hypnogogic hallucinations, leg jerks, nightmares and restlessness. These symptoms can develop suddenly or over many years. Narcolepsy often takes years to recognize since many medical conditions present with fatigue as a symptom.
To diagnose narcolepsy, a set of sleep studies is performed: an overnight diagnostic polysomnography followed by a multiple sleep latency test the next day. The sleep disorder is difficult to treat, thus it is advisable to be under the care of a physician who is specially trained in sleep medicine. Individuals with untreated narcolepsy are 10 times more likely to be involved in a motor vehicle accident than those who receive treatment.