Sleep paralysis — waking up without being able to move or speak — can provoke feelings ranging from mild anxiety to outright terror.

Because hallucinations often occur at the same time as the paralysis, this psychobiological experience feels supernatural to many people.

Here’s what research has revealed about this common sleep disturbance.

Sleep paralysis is essentially a glitch in your natural sleep-wake cycle. Your mind drifts into a waking state while some of your muscles are still in a sleep-induced state of paralysis.

Though it can be frightening to feel that you can’t move, sleep paralysis isn’t actually dangerous to your health.

Some studies indicate that around 30 percent of the population has experienced at least one episode of sleep paralysis.

It’s an age-old phenomenon: One Dutch doctor documented a patient’s terrifying sleep paralysis back in 1664.

He explained that his patient felt as if the devil was lying on her or a great dog was sitting on her chest. When she tried to throw it off, she couldn’t move.

Sleep paralysis is an almost universal experience. People in cultures all over the world have used their own folklore to explain the phenomenon.

In Newfoundland, Canada, people traditionally call it “old hag” syndrome because it feels as though a witch-like creature is perched on the chest.

According to a similar Nigerian tradition, a demon-woman pounces during your dreams and renders you motionless.

In Japan, sleep paralysis is explained as a spirit seeking vengeance by suffocating you in your sleep.

And in Brazil, the culprit is a roof-dwelling crone named Pisadeira who attacks those who sleep on their backs while their stomachs are full.

In the 1781 painting “The Nightmare,” Swiss-English artist Henry Fuseli depicted a young woman sprawled on her bed with a gremlin crouching on her abdomen.

These varied cultural representations all have the same element: fear.

That’s because people find it frightening not to be able to move or speak, especially when it’s accompanied by the distinct feeling that someone or something is preventing you from breaking free.

Your body undergoes several cycles as you sleep. The best known of these cycles is called rapid eye movement (REM) sleep.

During REM sleep, you’re likely to be dreaming. To prevent you from acting out your dreams, your brain releases neurotransmitters that lock down some of your skeletal muscle groups.

The paralysis sometimes prevents you from speaking or calling out. As REM sleep wanes, your brain reactivates your muscles.

Sometimes, though, the timing of the wake-sleep cycle doesn’t synchronize properly.

In the space between waking and sleeping, your mind becomes alert while your body still can’t move. Some of the visual and auditory elements of your dreams may still be playing out — hence the hallucinations.

Researchers have found that sleep paralysis can include a number of common symptoms:

  • the inability to move, speak, or breathe properly
  • hypnogogic hallucinations, or visions that happen while you’re falling asleep
  • hypnopompic hallucinations, or visions that happen as you’re waking up
  • auditory hallucinations, or imagining sounds
  • olfactory hallucinations, or imagining smells
  • a sense of heaviness or pressure on your chest
  • a feeling of being watched or touched, sometimes in a threatening or sexual manner
  • fear

Occasional sleep paralysis isn’t considered a medical problem.

Researchers think that certain people may be at risk for more frequent episodes of sleep paralysis, including people who:

In short, if you’re sleep-deprived, if your waking life is too stressful, or if you have anxiety in your daily life, you may be more likely to experience sleep disturbances.

There may also be a genetic influence on whether you have sleep paralysis episodes.

Sexual abuse survivors and sleep paralysis

If you’ve experienced sexual assault or abuse, the inability to control your body or the feeling of someone near you as you sleep may be more disturbing than it is for most people.

Research has shown that childhood abuse is associated with long-term sleep problems in adulthood. If sleep paralysis episodes leave you feeling anxious, it’s a good idea to talk to a healthcare professional about them, if it feels safe for you to do so.

There are treatments available to help you regain a restful night’s sleep.

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There are several things you can do to help reduce the chance you’ll experience sleep paralysis.

Practice good sleep hygiene

To increase the overall quality of your sleep, try these healthy sleeping tips:

  • exercise, but not too close to bedtime
  • avoid eating large meals close to bedtime
  • limit alcohol and caffeinated beverages
  • limit screentime
  • follow a regular sleep schedule
  • keep your bedroom cool and quiet

Consider cognitive behavioral therapy (CBT)

Cognitive behavioral therapy (CBT) may help you interrupt sleep paralysis episodes, giving you a sense of control over the unpleasant emotions and physical sensations.

Most people who try this approach work with a therapist. They may recommend the following steps:

  1. Write down your sleep paralysis episodes in a sleep journal.
  2. Work with your therapist to be sure you’re educated about sleep paralysis and the kind of hallucinations you’re having.
  3. Practice small movements (like wiggling a finger) that you can use to interrupt an episode.
  4. Practice diaphragmatic breathing, progressive muscle relaxation, distraction, and calming self-talk you can use to disrupt an episode.
  5. Use these relaxation techniques to lower your daily stress levels so you can prevent episodes.

Try meditation with muscle relaxation therapy

Sleep researcher Baland Jala recommends a variation on CBT to interrupt or stop the episode. His process is as follows:

  1. When the episode begins, reframe it. With your eyes closed, remind yourself that sleep paralysis is harmless and temporary.
  2. To distance yourself from fear, repeat to yourself that the anxiety is unnecessary and may make the episode last longer.
  3. Focus your attention on the image of something positive, ignoring any hallucinations.
  4. Consciously relax your muscles.

Ask your doctor about sedative antidepressants

If you’re having sleep paralysis so often that it’s affecting your ability to function during the day, or if the episodes are causing you too much anxiety, your doctor may prescribe medications that are normally used as sedative antidepressants.

Low doses of these medications have been effective at relieving sleep disturbances for some people.

Researchers recommend that these drugs be used alongside CBT.

It’s a good idea to get help from a healthcare professional if:

  • you have symptoms of narcolepsy
  • you have symptoms of sleep apnea
  • you’re experiencing sleep paralysis more and more frequently
  • anxiety about sleep paralysis is making you dread bedtime

If your doctor needs more information about your sleep paralysis, a sleep study at a local hospital or sleep center could be helpful.

“Old hag” syndrome is just a colloquial name for sleep paralysis, a common sleep disruption.

Though many cultures explain this phenomenon using supernatural terms, it’s actually a timing misstep in your sleep cycle.

It happens when your mind wakes up while your body is still in the temporary paralysis of REM sleep.

During an episode of sleep paralysis, you may feel trapped. You may see or hear hallucinations. While the experience can be frightening, it’s not dangerous to your health.

Sleep paralysis is more common for people with anxiety, certain mental illnesses, disrupted sleep schedules, and certain physical illnesses.

The good news is that there are treatment options available for you if the episodes are upsetting. CBT, muscle relaxation techniques, healthy adjustments to your sleep routines, and sedative antidepressants may help.