Sleep Paralysis: Symptoms & Signs

Medically Reviewed on 9/23/2020

Sleep paralysis is a form of paralysis (inability to move) that occurs upon falling asleep or waking up.

Signs and symptoms associated with sleep paralysis include

  • sensations of noises, smells, levitation, paralysis, and terror; and
  • images of frightening intruders.

It is thought that up to half of all people may experience sleep paralysis sometime during their life. The condition is not considered to be a sign of a serious problem.

Cause of sleep paralysis

Sleep paralysis is caused by an irregularity in passing between the stages of sleep. In particular, sleep paralysis occurs as a person is moving into or out of REM (rapid eye movement) sleep, the deepest part of sleep. It is most common during episodes of jet lag or after periods of sleeplessness and can be frightening.

Other sleep paralysis symptoms and signs

  • Images of Frightening Intruders
  • Sensations of Noises, Smells, Levitation, Paralysis, and Terror


Why do we sleep? See Answer

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Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.