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Sleep Paralysis: What Causes It and How to Stop It

Sleep paralysis is waking while your muscles are still in REM shutdown. It's common and usually lasts seconds to a couple of minutes. What triggers it, and what helps.

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Sleep Paralysis: What Causes It and How to Stop It

Sleep paralysis is waking up while your body is still in the muscle shutdown of REM, the dreaming stage of sleep. Your mind is awake, but you can't move or speak for a few seconds to a couple of minutes. It is frightening, and it is common. By one review's estimate, about 1 in 13 people have at least one episode in their life. The NHS says it's scary but not harmful, and the AASM says an episode usually ends on its own.

What causes sleep paralysis isn't fully known, but common links include short or broken sleep, an irregular schedule, sleeping on your back and stress. Below is what's happening, why some people see a figure in the room, and what you can do about it.

What is sleep paralysis?

During an episode you're aware of your bedroom but your body won't respond. The American Academy of Sleep Medicine (AASM) says you may be unable to speak or move your arms, legs, body or head, while you stay fully aware of what's happening. Cleveland Clinic says you can still move your eyes and breathe, although the NHS lists being unable to open your eyes as part of an episode. The NHS lists the common feelings as being awake but unable to move, sensing someone in the room, feeling pushed down, and fear.

It can happen at either end of sleep. Episodes as you drift off are called hypnagogic, and episodes as you wake up are called hypnopompic.

Doctors also sort it by what else is going on. When it happens without narcolepsy or another sleep disorder, it's called isolated sleep paralysis. When isolated episodes keep coming back, it's called recurrent isolated sleep paralysis. Narcolepsy itself is rare.

What causes sleep paralysis?

Nobody knows exactly why one person gets it and another doesn't. What researchers do know is when it happens and what makes it more likely. A 2018 review of 42 studies found it tied to a long list of factors, including poor and disrupted sleep, stress and trauma, and substance use.

The basic mechanism is timing. Normally your brain relaxes your muscles during REM sleep and switches them back on before you wake. In sleep paralysis you wake up, or slip into REM as you fall asleep, before that switch flips. In a Japanese lab study, researchers woke 16 volunteers in the night on purpose. That produced sleep paralysis in about 1 in 10 interruptions, nearly always when the person fell straight back into REM. A broken night can set up a similar overlap, which is how researchers brought it on in the lab.

Things linked to sleep paralysis:

  • Not enough sleep. The AASM says a lack of sleep makes it more likely.
  • An irregular schedule. The NHS names shift work and jet lag, and the AASM adds a sleep schedule that often changes.
  • Sleeping on your back. In surveys of 6,730 people, including 4,699 who had had episodes, more reported episodes on their back than in every other position combined. Lying on the back was 3 to 4 times more common during an episode than when people normally fell asleep.
  • Stress or disturbed sleep. In a survey of 635 Japanese students, about half of those who'd had an episode said they'd been under stress or sleeping irregularly just before.
  • PTSD, panic disorder and anxiety. The 2018 review found sleep paralysis especially common in post-traumatic stress disorder, and to a lesser degree panic disorder. Which way the link runs hasn't been settled.
  • Alcohol, some medicines and drugs. Harvard Health lists alcohol, substance use and some medicines, such as those for ADHD.
  • Family history. It can run in families.
  • Other sleep problems. Insomnia and sleep apnoea are both linked.
  • Narcolepsy. Sleep paralysis is one of its symptoms. See the GP box below for the other signs.

If you want the background on REM and how a night's sleep is built, see our guide to the stages of sleep.

Why can't you move or scream?

You can't move because REM sleep keeps most of your muscles switched off, and that hasn't worn off yet. The AASM says this "REM atonia" exists to stop you acting out your dreams. Dr Katherine Green, medical director of the University of Colorado Sleep Center, describes sleep paralysis as a lag "between when your brain wakes up and when that muscle connection returns."

The AASM says an episode may also leave you unable to speak, so calling out can be impossible.

Your breathing carries on. The AASM says "you are still able to breathe normally." A feeling of pressure on the chest or of being choked is common, but your breathing is still working.

Why do people see a "demon"?

The figure in the room is thought to be dream imagery carrying on into waking. Dr Green calls it "a transitional hallucination that resolves along with the paralysis," and says it is not paranormal.

Researchers at the University of Waterloo grouped these hallucinations into three kinds:

  • The intruder. A sense that someone is in the room, often with fear, sounds or a figure.
  • The incubus. Pressure on the chest, trouble breathing and sometimes pain.
  • Unusual body feelings. Floating, flying or seeming to leave your body.

In a related survey of 870 university students from the same group, almost 30% had had sleep paralysis, and about three-quarters of those had at least one hallucination. Fear went most closely with the sense of a presence. One explanation the researchers proposed is that the brain is in a state of high alert in this half-awake state, and the fear and the sense of a presence then feed further images, especially visual ones.

Many cultures have their own name for it. In Newfoundland it was an attack by the "Old Hag." In Japan it's kanashibari. In Turkey it's the Karabasan. Henry Fuseli's 1781 painting The Nightmare is often read as a picture of it. A clinician's guide says sleep paralysis has been thought to play a part in many beliefs about night-time demon attacks and alien abductions among people whose grasp of reality is otherwise intact. Dr Green says that just knowing it's a normal, well-explained part of sleep helps take the panic out of it.

Is sleep paralysis dangerous?

No. There's no evidence that an episode can kill you or cause lasting harm. One review found that isolated sleep paralysis hasn't been linked to any long-term effect. The NHS describes it as scary but not harmful, Harvard Health says it "is not a serious medical risk on its own," and a 2024 review called episodes benign.

The risk is indirect. Harvard Health notes that people with frequent or frightening episodes may start avoiding sleep, and losing sleep makes episodes more likely. Most people aren't badly troubled by it. In clinical interviews with 156 students who'd had it, about three-quarters felt fear during episodes, but 15% reported distress or disruption at a level a clinician would count as significant.

Is it a warning sign? Usually not. Occasionally it points to another sleep problem such as narcolepsy or sleep apnoea, which is why frequent episodes are worth mentioning to a GP.

How to get out of sleep paralysis

Nothing has been shown in trials to end an episode, and Cleveland Clinic says there's no way to stop one as it happens. The tips below come from sleep clinicians, not studies, so try them and keep what helps.

  • Start with something tiny. Cleveland Clinic says you may come out sooner if you focus on small movements, such as moving one finger, then two.
  • Breathe and wait. Dr Green's advice is to take a couple of deep breaths, remind yourself the episode is short-lived, and ride it out.
  • Try one big effort. Harvard Health and the AASM both say an intense effort to move can end an episode.
  • Name it. Dr Green says knowing it's a normal, well-explained part of sleep helps cut the panic, so reminding yourself that this is sleep paralysis and it will pass is reasonable to try.

Don't worry if nothing works every time. In the same student study, about 7 in 10 had tried to break their episodes, and only about half of those said their methods worked.

If you share a bed with someone who gets sleep paralysis, you can wake them safely. Cleveland Clinic and the AASM say talking to them or touching them can end an episode.

How to stop sleep paralysis happening again

Short and broken sleep are the triggers you can most easily change, so steadier sleep is the place to start. The NHS suggests:

  1. Aim for 7 to 9 hours of sleep a night.
  2. Go to bed and get up at roughly the same times every day. Our 7-step sleep schedule reset walks through it.
  3. Exercise regularly, but not in the last hour before bed.
  4. Avoid a big meal, smoking, alcohol or caffeine shortly before bed.
  5. Don't sleep on your back. A clinician's guide to sleep paralysis also suggests avoiding sleeping on your front, which leaves sleeping on your side.

Because stress and disturbed sleep were reported before episodes in some surveys, a wind-down routine and time to settle before bed are reasonable steps too, though no trial has tested them for sleep paralysis. Our habits for sleeping better cover the basics. If you wake in the small hours and struggle to settle, why you wake at 3am covers that separately.

When to see a GP

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You don't usually need a doctor for sleep paralysis. See a GP if:

  • you have episodes often and feel very anxious or scared to go to sleep
  • you're tired all the time because of it
  • you're very sleepy in the day, fall asleep suddenly, or your muscles go weak when you laugh or feel a strong emotion (possible signs of narcolepsy)
  • you act out your dreams in your sleep, such as moving or lashing out (a different REM problem that needs a sleep doctor)
  • your episodes seem linked to trauma or panic attacks (the NHS says a GP may be able to treat an underlying problem such as PTSD)

The NHS says a GP may be able to treat an underlying problem such as insomnia or PTSD, and that a specialist may offer a medicine usually used for depression, at a lower dose, or cognitive behavioural therapy (CBT). A 2024 review says no medicine is required. CBT designed for sleep paralysis is still early. A 2016 clinician's guide said a five-session programme had been written but not yet tested in trials, and a 2020 pilot of a meditation and relaxation approach involved just 10 people with narcolepsy.

For ongoing sleep problems, CBT-I (cognitive behavioural therapy for insomnia) is the recommended first treatment. Ask your GP.

If you're struggling, talk to your GP. UK: Samaritans 116 123. US: 988.

This is general information, not medical advice. NSDR is not a treatment for any condition.

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FAQ

Is sleep paralysis rare?

No, sleep paralysis is common. A review of 35 studies covering 36,533 people found that 7.6% of the general population had at least one episode, rising to 28% of students and 32% of psychiatric patients. The AASM says estimates vary widely, from about 5% to 40%.

Is sleep paralysis linked to lucid dreaming?

Yes, loosely. In an online survey of 1,928 adults, recruited partly through lucid dreaming and sleep paralysis forums, people who had more sleep paralysis also tended to have more lucid dreams, where you know you're dreaming. The two went with different things, though. Sleep paralysis went with poor sleep, anxiety and stress, and lucid dreaming with a vivid, positive imagination.

Can you make sleep paralysis happen on purpose?

You can make it more likely, but there's little reason to try. Researchers have triggered it in the lab by waking people for an hour during the night. Broken sleep is also a trigger for unwanted episodes, so deliberately disrupting your sleep risks more of the episodes you don't want.

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