Narcolepsy is characterized by excessive and overwhelming daytime sleepiness. Sudden and uncontrollable attacks of sleep occur without warning. These events are an inconvenience as they can happen at anytime. Nighttime sleep may be interrupted with frequent awakenings.

There is strong evidence that narcolepsy may run in families. While it occurs once in every 2000 births, it is 40 times more likely in immediate families after one member is diagnosed. Narcolepsy is a disorder of the central nervous system in which a stage of the sleep state, rapid eye movement (REM) sleep, occurs at unusual times, including in the wakeful state(called cataplexy). Also in narcolepsy, REM sleep occurs soon after a person falls asleep instead of an hour or more after Non-REM sleep. As a result, sleep paralysis and hallucinations (as out of dreams) may occur while falling asleep or waking up.

Signs and symptoms:

  • Excessive daytime sleepiness - when a person cannot force himself to stay awake at times of the day when he wants to be awake. The clock time of sleepiness may be predictable.
  • Cataplexy - a sudden loss of muscle control in the body, brought on by an emotionally loaded situation (evoking heavy laughter, or extreme excitement). This loss can be slight, such as slackening the jaw, or slurred speech or knee buckling; or severe, such as a complete collapse of the body. Cataplexy is a symptom unique to narcolepsy.
  • Sleep paralysis - when an awake person cannot move or talk for a short period of time, either right before falling asleep or directly after waking up. This can last a few seconds to minutes.
  • Hallucinations - memorable, scary dreams involving sights or sounds that occur right before falling asleep or directly after waking up.
  • Automatic behavior - when a person performs a routine task but is not aware of doing it, or later has no recollection of performing the activity.