Causes and Risk Factors of Sleep Paralysis

Triggers Include Sleep Deprivation, Narcolepsy, and Sleep Apnea

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Sleep paralysis is a relatively common experience—about 8% of people will experience it at one point or another, with higher rates for students, people of color, and people with psychiatric conditions.

It occurs when the features of rapid eye movement (REM) sleep intrude into wakefulness, leading to muscles that are unable to move, impaired breathing, and features of vivid dreams like fear and hallucinations. This disconnect between the brain and the body's muscles can cause terrifying symptoms.

What are the causes of sleep paralysis? Are there things you can do to avoid experiencing it?

There may be some factors that play into sleep paralysis that are beyond your control, but some self-induced behaviors may potentially trigger an episode of sleep paralysis in the right situation. By learning how certain causes can potentially lead to sleep paralysis, you may be better able to avoid it.

Causes of Sleep Paralysis
Verywell / Brianna Gilmartin 


Sleep paralysis is simply an extension of the dream state (called REM or rapid eye movement sleep), so it is technically harmless. However, it is not something people seek to repeat once they experience it, as it can be unpleasant.

People experience an inability to move, speak, or control their body, despite being conscious and wanting to. It is sometimes accompanied by hallucinations, which add to the disagreeable nature of the situation.


The causes of sleep paralysis are surprisingly mundane. Consider the two states of consciousness—being asleep and being awake. There is normally a transition period between these states.

During this transition, elements of consciousness—such as an awareness of your environment—may be preserved, while aspects of sleep (such as dreaming) may begin. Typically, this transition is brief and uneventful. However, a prolonged or disrupted transition may predispose you to the unusual experiences of sleep paralysis.

REM Sleep Problems

In particular, sleep paralysis is believed to relate to a problem regulating REM sleep. It is during REM that our body is paralyzed so that we are unable to act dreams out.

This muscle relaxation, called atonia, may sometimes occur while you are awake. As such, you will be unable to move, even if you are conscious. This is one of the common features of sleep paralysis.

Clearly, there are certain triggers of sleep paralysis. It often occurs during periods of sleep deprivation and stress. Many people experience it when their sleep schedule is disrupted, no matter the reason.

Those with shift work sleep disorder may be at increased risk, according to a 2016 review study. If sleep is attempted during the day, it is more likely for interruptions of sleep to occur.

In addition, it is possible to trigger sleep paralysis experimentally by disrupting REM. In a controlled environment (such as a sleep study), this could be attempted—and has been shown to incite the phenomenon.

Psychiatric Disorders

There also appears to be a strong association with psychiatric disorders like anxiety and depression. The use of alcohol or other drugs may also provoke an attack of sleep paralysis. For some people, a family history of sleep paralysis becomes evident, though a genetic cause of the condition is not known.

Sleeping Position

Most people with sleep paralysis report that it occurs when they are sleeping on their backs (a supine sleeping position). However, less frequently, others have reported it occurring when sleeping on their stomachs or sides as well.


The vast majority of people suggest that sleep paralysis happens while falling to sleep (a hypnagogic phenomenon), yet it can also occur when awakening from sleep. It typically occurs at night, but it has also been known to occur during daytime naps.

Other Sleep Disorders

Sleep paralysis can also occur in association with other sleep disorders that fragment sleep, including obstructive sleep apnea and narcolepsy. Sleep apnea is often worsened by being on one's back and in REM sleep, so other symptoms, such as snoring and waking to urinate, may suggest a need for testing.

Symptom of narcolepsy include sleepiness, hallucinations, and cataplexy (sudden and transient loss of muscle tone). Treatment of these conditions may reduce the frequency of sleep paralysis episodes.

Unscientific Explanations

Sleep paralysis has occurred throughout recorded history, and there are countless examples in literature and art of the phenomenon. In some parts of the world, the condition is called the "old hag."


Many people describe the experience in religious terms. Some might blame a ghost, demon or devil as the cause. The terrifying elements of sleep paralysis are easily ascribed to a malevolent presence. Others suggest it is due to aliens. There is no scientific evidence for such beliefs.

Medical and Mental Problems

Others worry that another medical or mental health problem may be to blame. The list of potential medical maladies that might explain the experience of sleep paralysis is diverse, ranging from seizures to heart attacks to strokes. Some even think (at least briefly) that they have died.

Still, other people worry that they have gone insane and do not discuss it because they are worried about how others might react to their experience. The episode of sleep paralysis is self-limited, without lasting consequences, and so these explanations are proven to be false.

Dreams and Nightmares

Finally, some people worry that sleep paralysis is just a dream or a nightmare. This may actually be the closest to the truth. As described above, sleep paralysis occurs when there is a breakdown between the states of consciousness and sleep, when our dream state intrudes upon our wakefulness.

Fortunately, many people are reassured by a better understanding of the phenomenon of sleep paralysis, so that if it recurs they know how to interpret the experience and can more easily tolerate it until it inevitably ends.

A Word From Verywell

For most people, sleep paralysis occurs rarely, but if it occurs more frequently and you find it particularly bothersome, you may wish to speak to your healthcare provider for a referral to a board-certified sleep medicine healthcare provider. Treatment of narcolepsy or sleep apnea, if present, may be helpful.

Even if your sleep paralysis occurs in isolation, if it has become disruptive to your life, treatment options are available.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Sharpless BA, Barber JP. Lifetime prevalence rates of sleep paralysis: A systematic review. Sleep Med Rev. 2011;15(5):311-5. doi:10.1016/j.smrv.2011.01.007

  2. Sharpless BA. A clinician's guide to recurrent isolated sleep paralysis. Neuropsychiatr Dis Treat. 2016;12:1761-7. doi:10.2147/NDT.S100307

  3. Denis D, French CC, Gregory AM. A systematic review of variables associated with sleep paralysis. Sleep Med Rev. 2018;38:141-157. doi:10.1016/j.smrv.2017.05.005

By Brandon Peters, MD
Brandon Peters, MD, is a board-certified neurologist and sleep medicine specialist.