Sleep paralysis: the weight on your chest

You wake in the dark and try to roll over, and nothing happens. You cannot lift an arm or call out. There is a weight on your chest, or a sense that someone is standing in the doorway. Then, after what feels like a long time, it lets go.

This is sleep paralysis. It can be terrifying, and it is not dangerous.^[6]

What is happening

During REM sleep, the stage with the most vivid dreams, the brain keeps most of the body’s muscles still, which stops us acting out our dreams. In sleep paralysis, you become aware before that stillness has switched off. Your mind is awake; your muscles are still in REM mode.^[2]

Because the dreaming brain has not fully let go, episodes often come with vivid hallucinations: a presence in the room, footsteps, a figure, pressure on the chest. Your eyes can usually move, and you may have some control over your breathing, but a feeling of suffocation is common. Episodes are usually brief, from seconds to several minutes; one study put the average at about six minutes.^[2] In our atlas, the weight on your chest looks at the experience itself.

How common is it?

More common than most people think. A 2011 systematic review pooled 35 studies with more than 36,000 people in total. About 7.6 per cent of the general population had experienced at least one episode, compared with 28.3 per cent of students and 31.9 per cent of psychiatric patients. Among people with panic disorder, the figure was 34.6 per cent.^[1] The studies used different questions and samples, so these are best read as rough guides. And most people who have sleep paralysis do not experience significant distress or disruption to daily life because of it.^[2]

The old hag and kanashibari

Many cultures have names for this experience. In Newfoundland it was known as the old hag: a sleeper wakes pinned down and terrified, often sensing a malign presence. The folklorist David Hufford collected these accounts there, and in his 1982 book, “The Terror That Comes in the Night”, he compared them with what sleep researchers call sleep paralysis. He also met people who had never heard of the tradition but described the same experience.^[3]

In Japan, the same experience is called kanashibari. In a 1987 survey of 635 Japanese college students, about 40 per cent said they had had at least one episode, and about half of them linked it to stress or a disturbed sleep pattern beforehand.^[4] Many people now explain it differently. In a large international survey published in 2023, most people who had experienced sleep paralysis put it down to “something in the brain”; about 7 per cent believed the cause was supernatural.^[6]

What makes it more likely

A 2018 systematic review of 42 studies looked at what is linked to sleep paralysis. Themes included poor or disrupted sleep, stress and trauma, substance use, physical illness, genetic influences, anxiety symptoms and some psychiatric conditions. It appears to be particularly common in post-traumatic stress disorder and, to a lesser degree, in panic disorder.^[5] In the 2023 survey of more than 6,800 adults, people who had experienced it reported shorter sleep, took longer to fall asleep and had more insomnia symptoms.^[6] Episodes are also more likely when sleeping on your back.^[2] These are associations: they show what tends to go together, not what causes what.

What helps during an episode

The honest answer is that the evidence is thin. As of 2016, no randomised trial had tested a treatment for recurrent sleep paralysis,^[2] so most advice comes from small studies and from what people with sleep paralysis report. Things many people find useful:

• Name it. “This is sleep paralysis. My body is still in dreaming sleep. It will pass.” Knowing what is happening can take some of the fear out of it.
• Let your breathing be slow and easy. Your chest may feel heavy, but you are not being smothered.
• Turn your attention inward. One proposed approach, meditation-relaxation, combines reframing the episode, stepping back from the frightening images, focusing on something calm, such as a good memory, and relaxing your muscles rather than straining against them. In a pilot study of ten people with narcolepsy, the six who used it for eight weeks had about half as many days with sleep paralysis, unlike a small comparison group who practised deep breathing.^[7] It was a tiny study, and the method still needs testing in larger groups.
• Try to move. In the 2023 survey, physical action, such as trying to move part of the body, was among the ways people said they broke an episode, though no method worked for everyone.^[6]

Making the next one less likely

• Protect your sleep. Regular bedtimes and wake times, and enough sleep, matter, since short and broken sleep are linked to episodes. In the 2023 survey, adjusting sleep patterns and changing sleep position were among the prevention strategies people rated as working.^[6]
• Try sleeping on your side. Episodes are more likely on your back.^[2]
• Go gently in the evening. Avoiding alcohol and caffeine close to bedtime is part of the sleep advice clinicians suggest.^[2] A short wind-down helps too; here is one way to build it.

When to see a doctor

Occasional sleep paralysis does not need medical care. It is worth seeing a doctor if:

• episodes are frequent, or you have started to dread going to sleep;
• you feel very sleepy during the day, even after a full night, or fall asleep at unexpected times;
• strong emotions, like laughter or surprise, make your muscles suddenly go weak.

The last two can be signs of narcolepsy, a rare condition in which sleep paralysis can appear alongside excessive daytime sleepiness and cataplexy, that sudden, emotion-triggered weakness. A doctor can often tell them apart by asking questions, and sometimes with a sleep study.^[2]

One safety note. Sleep paralysis affects the whole body and passes on its own, usually within minutes. Weakness that lasts once you are fully awake, or that affects one side of your body or face, is something different: call your local emergency number.

If an episode leaves you too shaken to sleep, Baku’s Nightlight is there: ember on black, a slow breathing pulse, and nothing to read.