Nightmares and sleep

What is sleep paralysis, and is it dangerous?

Sleep paralysis is a short spell, from seconds to a few minutes, when you’re awake but can’t move or speak as you fall asleep or wake up (AASM, 2020). It can be frightening, and some people sense someone in the room, but it isn’t dangerous on its own (NHS, 2026). You keep breathing normally, and it usually ends by itself (AASM, 2020). Frequent episodes are worth taking to a doctor (Cleveland Clinic, 2024).

Last updated: 2026-10-13.

What is happening in your body during sleep paralysis?

During sleep paralysis, your mind has woken while your muscles are still in REM sleep, the stage when people dream most (Cleveland Clinic, 2024; National Institute of Neurological Disorders and Stroke [NINDS], 2026). NINDS adds that in REM sleep, your brain keeps your muscles limp so you don’t act out your dreams. Sleep paralysis happens when that stillness, called REM atonia, comes as you fall asleep or wake up (American Academy of Sleep Medicine [AASM], 2020).

During an episode you may be unable to speak or to move your arms, legs, body and head, yet you can still breathe normally and move your eyes, and you stay fully aware of what is happening around you (AASM, 2020; Cleveland Clinic, 2024). The AASM adds that some people have one episode in their whole life, others many in a year.

Sleep paralysis isn’t a night terror: during a night terror the person is asleep, while in sleep paralysis you’re awake (NHS, 2025).

Is sleep paralysis dangerous?

Sleep paralysis isn’t dangerous on its own (Cleveland Clinic, 2024). The NHS (2026) calls it scary but harmless. The AASM (2020) says it is not a serious medical risk on its own, and it doesn’t keep you from getting the sleep you need.

A weight on your chest can feel like suffocation (Cleveland Clinic, 2024), but you go on breathing normally all the way through (AASM, 2020). The fear can outlast the episode, though (Cleveland Clinic, 2024). Even one episode can make you nervous about going to sleep, and that can affect how you feel and function during the day. If episodes make you anxious, talk to your doctor (AASM, 2020).

Why do people sense someone in the room or a weight on their chest?

Sensing someone in the room can be a kind of hallucination (AASM, 2020), and so can a weight on your chest (Cheyne et al., 1999). During an episode, some people see, hear or feel things that aren’t there. In several large samples, these experiences fell into three groups (Cheyne et al., 1999):

• a sensed presence, with fear, and sounds or sights
• pressure on the chest, with difficulty breathing
• unusual body feelings, such as floating, flying, leaving your body or even bliss

The researchers proposed that the sense of a presence starts in a state of high alert in the brain, and that the chest pressure comes from the way the paralysis changes how breathing feels. They note that descriptions are remarkably consistent across time and cultures, and fit what is known about REM sleep. Many cultural traditions have their own accounts of these experiences, and this page doesn’t rule on them.

Why do estimates of sleep paralysis range from 5% to 40%?

Estimates of sleep paralysis range widely, partly because they depend on who is asked (Sharpless & Barber, 2011). Their review pooled 35 studies covering 36,533 people and found big differences between groups.

Sleep paralysis tends to start in the teen years, at an average age of 14 to 17 (AASM, 2020). It is most common in people’s 20s and 30s.

Can sleeping on your back, stress or shift work bring on sleep paralysis?

Back sleeping, stress and changing sleep schedules have all been linked with sleep paralysis (AASM, 2020). The AASM lists a lack of sleep, a sleep schedule that often changes, mental stress and sleeping on your back. It notes that sleep paralysis may also run in families. The NHS (2026) adds insomnia, sleep disrupted by shift work or jet lag, narcolepsy, post-traumatic stress disorder (PTSD), generalized anxiety disorder and panic disorder.

In two studies of 6,730 people, 4,699 of whom had had sleep paralysis, more people reported episodes while lying on their back than in all the other positions put together (Cheyne, 2002). In the same studies, lying on the back was 3 to 4 times more common during episodes than when people normally fell asleep.

A review of 42 studies linked sleep paralysis with substance use, stress and trauma, genes, physical illness, sleep problems and anxiety symptoms (Denis et al., 2018). In the same review, it appears to be especially common in people with PTSD, and less so in people with panic disorder. Links like these don’t show cause.

How do you come out of an episode, and lower the odds of the next one?

No method is sure to stop an episode of sleep paralysis (Cleveland Clinic, 2024). Small movements may help. The Cleveland Clinic suggests focusing on moving one finger, then two, which may bring you out sooner. An intense effort to move can also end an episode, and so can someone touching you or speaking to you (AASM, 2020).

To lower the odds of another episode, the NHS (2026) suggests:

• getting 7 to 9 hours of sleep regularly
• going to bed and getting up at about the same times each day
• avoiding a big meal, smoking, alcohol or caffeine shortly before bed
• not sleeping on your back

When stress or anxiety plays a part, cognitive behavioral therapy (CBT) may help (AASM, 2020). After an episode, it’s natural to feel tired, confused and scared (Cleveland Clinic, 2024). Be kind to yourself, rest more if you need to, and talk to someone close to you.

Could sleep paralysis be a sign of narcolepsy or another sleep problem?

Sleep paralysis can be one sign of narcolepsy, so what matters is whether other signs come with it (AASM, 2020). The AASM lists them as excessive daytime sleepiness, broken sleep at night, hallucinations around sleep and cataplexy. In narcolepsy, daytime sleepiness doesn’t improve even after a full night’s sleep (NINDS, 2026). Cataplexy means sudden muscle weakness, often set off by strong emotions such as laughter or anger. If you have any of these signs, talk to a sleep doctor (AASM, 2020).

You don’t usually need medical help for sleep paralysis unless it’s affecting your sleep or your mental health (NHS, 2026). See a GP, or family doctor, if you often have sleep paralysis and feel very anxious or scared to go to sleep, or tired all the time. A GP may treat a condition behind the episodes, such as insomnia or PTSD. If that doesn’t help, the NHS says a sleep specialist may suggest medicine or CBT. If frightening dreams are part of the picture, see when nightmares need a doctor.

Sources

1. American Academy of Sleep Medicine. (2020, August). Sleep paralysis. Sleep Education. sleepeducation.org/sleep-disorders/sleep-paralysis/
2. Cheyne, J. A. (2002). Situational factors affecting sleep paralysis and associated hallucinations: Position and timing effects. Journal of Sleep Research, 11(2), 169–177. doi.org/10.1046/j.1365-2869.2002.00297.x
3. Cheyne, J. A., Rueffer, S. D., & Newby-Clark, I. R. (1999). Hypnagogic and hypnopompic hallucinations during sleep paralysis: Neurological and cultural construction of the night-mare. Consciousness and Cognition, 8(3), 319–337. doi.org/10.1006/ccog.1999.0404
4. Cleveland Clinic. (2024, July 3). Sleep paralysis. my.clevelandclinic.org/health/diseases/21974-sleep-paralysis
5. Denis, D., French, C. C., & Gregory, A. M. (2018). A systematic review of variables associated with sleep paralysis. Sleep Medicine Reviews, 38, 141–157. doi.org/10.1016/j.smrv.2017.05.005
6. National Institute of Neurological Disorders and Stroke. (2026, August 25). Narcolepsy. ninds.nih.gov/health-information/disorders/narcolepsy
7. NHS. (2025, November 24). Night terrors and nightmares. nhs.uk/conditions/night-terrors/
8. NHS. (2026, September 9). Sleep paralysis. nhs.uk/conditions/sleep-paralysis/
9. Sharpless, B. A., & Barber, J. P. (2011). Lifetime prevalence rates of sleep paralysis: A systematic review. Sleep Medicine Reviews, 15(5), 311–315. doi.org/10.1016/j.smrv.2011.01.007