Sleep Paralysis is a frightening phenomenon most people have experienced at least once. Repeated attacks of sleep paralysis are very rare except in patients with narcolepsy or in a few case reports of families in which all members are affected, suggesting a genetic basis. Usually sleep paralysis is simply a slight deviation from the normal REM sleep-to-wakefulness transition.

During REM sleep, our reflex system is paralyzed, preventing us from acting out our dreams. There is an excellent chance that the final morning awakening will occur during REM sleep. If we wake up rapidly (perhaps due to a disturbing dream or noise in the environment), we may feel that our body is paralyzed, i.e., still in REM sleep, but our consciousness is returning—we are entering a state of wakefulness.

The consequence of being abruptly awakened from a hallucinatory experience (dreaming) but unable to move is a feeling of terror, a fear of losing control. Most people try to fight sleep paralysis. They struggle to wake up, but this usually prolongs the frightening episode. A few patients have given accounts that they simply try to sleep rather than trying to wake up, the episode ends, and they later awaken without difficulty.