Sleep paralysis: why you can't move and how to stop it

What is sleep paralysis?

Sleep paralysis is a short spell, just after waking up or just before falling asleep, when you are conscious but cannot move or speak. Your mind has surfaced, but your body is still in the state of REM sleep, the stage most vivid dreams come from, when most of your muscles are switched off.

It is more common than people think. A systematic review by Sharpless and Barber, pooling 35 studies, estimated that about 7.6% of the general population has had at least one episode, rising to 28.3% among students and 31.9% among psychiatric patients.

Long before anyone measured it, many cultures gave the experience a name and a culprit:

• England: the mare of Old English folklore was a spirit that sat on sleepers' chests. It survives in the word nightmare.
• Newfoundland: people speak of being "hagged" by the Old Hag.
• Japan: kanashibari, literally "bound in metal".
• Brazil: the Pisadeira, an old woman who treads on the chests of sleepers.

These stories describe the experience remarkably well, but they are not evidence that something visits you at night.

What does an episode feel like?

An episode usually starts in one of two ways. Either you wake from a dream and find that your body won't respond, or you are drifting off and feel yourself "lock" while still aware.

In the body

• You can't move your arms, legs or head, however hard you try.
• You can't speak or call out. Sometimes you can move or open your eyes, sometimes not.
• Your chest feels heavy, as if something were pressing on it, and your breathing seems shallow.

In what you perceive

• A sense of presence: someone, or something, is in the room.
• Things you see: a shadow in the corner, a figure by the door or leaning over the bed.
• Things you hear: footsteps, breathing, whispers, buzzing.
• Bodily sensations: floating, spinning, falling, or seeing yourself from above.

According to the Sleep Foundation, around 75% of episodes include hallucinations of this kind. Episodes usually last from a few seconds to several minutes and end on their own, sometimes as soon as you manage a movement or someone touches you or speaks to you.

What is happening in the brain?

During REM sleep, the brainstem actively relaxes most of the body's muscles. This REM atonia stops you from acting out your dreams. Breathing and eye movements carry on.

Sleep paralysis is a mixed state: part of the brain has woken up while the atonia, and sometimes the dream imagery, are still running. As the NHS puts it, the muscles stay unresponsive while the brain is active. Why this hand-over between sleep and waking misfires on some nights is still being studied.

This is why it feels so real: you are awake enough to see your bedroom, and still dreaming enough for dream images to be laid over it. Seeing things during an episode does not mean you are "losing it".

What makes episodes more likely?

Anyone can have an episode, and there is rarely a single cause. A systematic review of 42 studies by Denis, French and Gregory (2018) found links with disrupted sleep, stress and traumatic experiences, anxiety symptoms, substance use and some psychiatric conditions. The strongest association was with post-traumatic stress disorder. A family history of sleep paralysis also plays a part, according to the NHS.

Short or irregular sleep

• Not enough sleep, especially several short nights in a row.
• An irregular schedule: shift work, jet lag, very late weekends.
• Sleeping on your back, which the NHS notes makes episodes more likely.
• Other sleep problems: insomnia, sleep apnoea, and narcolepsy, of which sleep paralysis is a recognised symptom.

Stress and mental health

• Periods of heavy stress or emotional upheaval.
• Anxiety disorders, panic disorder in particular, and PTSD.
• Alcohol and some substances, and also stopping alcohol or certain antidepressants abruptly, which can disturb REM sleep.

Why the presence, the weight and the floating?

The images of sleep paralysis are strikingly similar from one person to the next. Psychologist J. Allan Cheyne and his colleagues grouped them into three families. Their explanations remain hypotheses, but they help make sense of what you went through.

The intruder: someone is in the room

A sense of presence, footsteps, a figure, and often intense fear. One explanation is that the brain's threat-detection system is active during REM sleep. Awake, unable to move and on alert, the brain looks for the source of the alarm, and dream imagery gives it a shape. In other words, the figure is a product of the fear, not its cause.

The incubus: the weight on your chest

Pressure, a feeling of suffocation, sometimes the impression that someone is sitting on you. During REM sleep, breathing relies mainly on the diaphragm while other chest muscles stay relaxed. Trying to take a deep breath in that state can feel like pushing against a weight. Your breathing carries on by itself throughout.

Unusual bodily sensations: floating, falling, leaving the body

Floating, flying, spinning, dropping, or seeing yourself from above. A likely explanation is a mismatch: the brain's balance and movement systems send signals of motion, while the motionless body sends back none. The result can feel like leaving your body.

What to do during an episode

Knowing what is happening already takes away part of the fear: an episode is frightening, not dangerous, and it ends on its own. None of these approaches works for everyone; keep what helps you.

1. Start with a very small movement

Rather than trying to sit up, focus on one finger or one toe, or try to clench your fist. The Sleep Foundation suggests these small movements as a way to bring an episode to an end.

2. Breathe slowly and name what is happening

Breathe calmly, without forcing a deep breath: your breathing continues on its own, even if your chest feels heavy. Tell yourself silently: "This is sleep paralysis. It will pass." Naming it can take some of the heat out of the panic that makes the seconds feel so long.

3. Or the opposite: stop fighting

Some people do better by not struggling at all. Psychologist Baland Jalal has proposed a four-step approach he calls MR therapy (meditation-relaxation): reframe the meaning of the episode (benign and temporary), keep an emotional distance from what you see, turn your attention inward to something neutral or reassuring, and relax your muscles. It was presented through case examples and has not yet been tested in large trials.

4. Afterwards

• Switch on a light or get up for a minute if you're afraid of slipping straight back into it.
• Write down a few lines about the episode: time, position, what you saw, how it ended.

How to have fewer episodes

There is no guaranteed way to prevent sleep paralysis. But the factors that make it more likely are often ones you can act on.

Protect your sleep

• Aim for 7 to 9 hours a night, the range the NHS recommends for adults.
• Keep regular times for going to bed and getting up, weekends included.
• Exercise regularly, but not right before bed.
• Go easy in the evening on large meals, alcohol and caffeine.
• Put screens away about an hour before bed.
• Sleep on your side if your episodes tend to happen on your back; a pillow wedged behind you can stop you rolling over.
• Lower the pressure with a few minutes of slow breathing, or by writing down what is on your mind.

Keep a log of your episodes

Fictional example: what a useful entry can look like.

• Night: "Tuesday, 6:40 a.m., on my back, just before the alarm. About five hours of sleep after a late deadline."
• Episode: "Couldn't move for what felt like a minute. A dark figure by the door, footsteps."
• How it ended: "I managed to move my thumb, then everything came back."
• Question to keep: "Do my episodes follow short nights, or nights on my back?"

One entry proves nothing. After a few weeks, notes like these show whether episodes follow short nights, a particular position or stressful periods, and they are useful to bring to a doctor. Our dream journal guide explains how to set up the habit.

If you practise lucid dreaming

Some lucid dreaming techniques involve waking in the night, then going back to sleep while staying aware. If your episodes increase, ease off: disrupted sleep is one of the factors linked to sleep paralysis.

When to see a doctor

An occasional episode does not need medical attention. Talk to a doctor if:

• episodes are frequent and you feel very anxious or scared about going to sleep;
• you are constantly tired because of poor sleep;
• you are very sleepy during the day or fall asleep suddenly at inappropriate moments;
• you have bouts of sudden muscle weakness, for instance when laughing, which can be a sign of narcolepsy;
• episodes started after a trauma, or come with frequent nightmares and distress during the day.

A doctor can look for an underlying cause, such as insomnia, sleep apnoea, narcolepsy or PTSD, and treat it. If needed, they may refer you to a sleep specialist, who can run a sleep study (polysomnography). According to the NHS, treatment options include cognitive behavioural therapy (CBT) or, in some cases, a low-dose antidepressant.