sleep paralysis

sleep paralysis, total inability to move for a very brief period that occurs as one is either falling asleep or awakening from sleep. Sleep paralysis can affect individuals of any age, and many people experience an episode at some point in their lifetime. Teenagers and young adults and persons with certain psychiatric disorders, including narcolepsy and post-traumatic stress disorder, occasionally experience episodes of sleep paralysis on a somewhat regular basis (e.g., monthly). Sleep paralysis generally is not a serious medical concern, though it can be disturbing and may be a significant source of fear for some individuals.

An episode of sleep paralysis typically is characterized by an inability to move the limbs, body, or head and an inability to speak, with the affected person being completely aware of the paralysis. These experiences result from elements of REM dreaming intruding into wakefulness. Episodes typically last from a few seconds to several minutes and may be accompanied by vivid, waking hallucinations in which individuals report seeing, hearing, or sensing another being or object nearby. A common hallucination involves sensing the presence of a dangerous, often menacing, being. Other sensations that may be experienced during an episode are a feeling of heavy pressure on the chest and intense fear. Lack of sleep, disrupted sleep, and stress can trigger an episode.

Sleep paralysis does not affect the respiratory system or eyes and is closely associated with rapid eye movement (REM) sleep, major characteristics of which include muscle atonia (extreme relaxation and inability to contract) and vivid dreaming. Muscle paralysis during sleep is considered beneficial in that it prevents individuals from physically acting out dreams. However, as individuals regain consciousness, there can be temporary overlap with REM-sleep atonia. During this state, the amygdala, the brain’s emotional center, is highly active, while the prefrontal cortex, which serves as the brain’s logical control center, is less active, facilitating the occurrence of fear-driven, dream-like hallucinations.

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Sleep paralysis typically can be resolved through proper sleep hygiene and stress reduction. In some instances, affected persons may be treated with cognitive behavior therapy. Sleep paralysis may be relieved with medication in persons with underlying psychiatric disorders.