Understanding the Symptoms, Features, and Frequency of Sleep Paralysis

Dream Paralysis May Persist from REM Sleep into Wakefulness

Sleep paralysis occurs more when lying on one's back, but what are the symptoms and causes of it?
Sleep paralysis occurs more when lying on one's back, but what are the symptoms and causes of it?. Blend Images - JGI/Jamie Grill/Brand X Pictures/Getty Images

Sleep paralysis sounds unbelievable. You wake from sleep. As you lie in bed, you feel like someone is standing over you in the darkness. You try to move your head only slightly to take a subtle glance, but you can't. Someone—something—is surely holding you down. You attempt to struggle, to thrash your arms and legs, but you are frozen in place. Sheer panic washes over you as your paralysis lingers.

 Though this may sound all too unreal, sleep paralysis is indeed a very real experience. What are the symptoms of sleep paralysis? Learn about the features and frequency of this condition and how it relates to REM sleep's dreaming characteristics persisting into wakefulness.

What Exactly Is Sleep Paralysis?

If you have experienced something similar while awakening, you are familiar with the unforgettable horrors of sleep paralysis. Sleep paralysis is a transient inability to move or speak as one goes from sleep to wakefulness, without other findings characteristic of narcolepsy. In sleep paralysis, this often occurs while awakening (hypnopompic) as opposed to falling asleep (hypnagogic), which is more common in narcolepsy. It may be more likely to occur towards morning because that is when rapid eye movement (REM) sleep associated with vivid dreaming predominates.

Symptoms and Features of Sleep Paralysis

There are some common features that characterize the symptoms of sleep paralysis, including:

  • Eye movements are typically preserved.
  • It more often occurs while sleeping on one’s back.
  • Visual and auditory hallucinations often occur and may include a sense of an evil presence, of being touched, or hearing voices or noises in the room.
  • Occasionally faces or people may be seen at the bedside.
  • A sense of breathlessness (or chest pressure, even someone standing on one’s chest) may exist. It is still possible to breathe, due to the diaphragm's preserved function.

    How Often Does Sleep Paralysis Occur?

    It is common and may be experienced by 20% to 60% of people, depending on the population examined. In a study of college students, 21% were found to have had at least one episode of sleep paralysis, but only 4% had 5 or more episodes.

    What Causes Sleep Paralysis?

    It is believed to be precipitated by sleep deprivation, stress, and sleep schedule disruption. In experiments, it has been shown to occur with disruption of rapid eye movement (REM), or dream sleep. It also is associated with anxiety disorders. 

    Although there may be certain triggers, ultimately sleep paralysis is believed to be a problem with the regulation of REM. During this phase of sleep, the body is kept relaxed so that dreams are not acted out. If this relaxation, or atonia, occurs while the person is awake, it can cause temporary paralysis. This may be experienced when a REM period is disrupted. 

    Obstructive sleep apnea may also trigger awakenings due to breathing disruption and cause sleep paralysis.

    Treatment of Sleep Paralysis

    Fortunately, sleep paralysis is harmless. It is self-limited, ending by either falling back asleep or waking more fully out of it. It may occur infrequently. Once it is recognized, reassurance is usually enough. It can still be very scary as it occurs.

    Though these episodes may be frightening, the disorder itself is not harmful and will generally resolve on its own. No treatment is needed, but avoiding sleep deprivation, stress, and other precipitants may be helpful. These are summarized in the sleep hygiene guidelines.

    For those who suffer from multiple episodes and who are unable to tolerate the psychological distress, a selective serotonin receptor inhibitor (or SSRI) may be prescribed. These medications suppress REM sleep. 

    In addition, evaluation by a physician may be important to address sleep, mental health, or other medical disorders that can disrupt sleep. If it recurs, and is particularly upsetting, an evaluation by a board-certified sleep specialist or a sleep study may be indicated.

    Sources:

    Kryger, MH et al. "Principles and Practice of Sleep Medicine." Elsevier, 6th edition, 2016.

    McCarty, D.E. et al. "A case of sleep paralysis with hypnopompic hallucinations." Journal of Clinical Sleep Medicine. 2009;5(1):83-84.

    Morton, K. "Paralyzed at Night: Is Sleep Paralysis Normal?Stanford Sleep & Dreams. 2010.

    Spanos, N.P. et al. "The frequency and correlates of sleep paralysis in a university sample." J Res Pers. 1995;29:285-305.

    Takeuchi, T. et al. "Factors related to the occurrence of isolated sleep paralysis elicited during a multiphasic sleep-wake schedule." Sleep 2002;25:89-96.

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