Sleep Paralysis

Sleep paralysis is a state, occurring while falling asleep or waking up, in which a person is conscious but completely unable to move, an episode that often includes hallucinations and a resulting sense of fear, and that generally lasts no more than a few minutes. It can happen to an otherwise healthy person, can occur alongside narcolepsy, or can run in families through specific genetic changes, and episodes can be triggered by sleep deprivation, psychological stress or an irregular sleep schedule; the underlying mechanism is thought to involve a dysfunction of REM sleep. Between about 8 and 50 percent of people experience sleep paralysis at some point in their life and about 5 percent have it regularly, affecting men and women equally, and the experience has been described throughout history and is believed to have contributed to folklore and reports of alien abduction and other paranormal encounters.