What Is Sleep Paralysis? Causes and Ways to Make It Less Likely

Sleep paralysis is a brief spell, on falling asleep or waking up, when the mind is awake but the body cannot move or speak. It usually lasts from a few seconds to a couple of minutes and ends by itself. It can be frightening, particularly the first time, but it is not considered dangerous in itself.

What happens in the body

During rapid eye movement (REM) sleep, the stage most linked with vivid dreams, the brain switches off most voluntary muscle activity. This stops people from acting out their dreams. Sleep paralysis is thought to happen when part of the brain wakes up while that muscle "off switch" is still engaged. You are aware of the room, yet your arms and legs will not respond.

Because the dreaming brain is still partly active, the experience can blend with dream imagery. That accounts for some of its most unsettling features.

What people commonly experience

• being unable to move the body or speak, although the eyes can often open
• a sense that someone or something is in the room
• pressure on the chest, or a feeling of not being able to take a full breath
• sounds, shapes or shadows that seem completely real
• fear or panic, followed by relief when movement returns

Breathing carries on automatically throughout. The chest pressure is uncomfortable, but the muscles that keep you breathing are not switched off.

Types of episode

Name	When it happens
Hypnagogic	While drifting off to sleep
Hypnopompic	While coming out of sleep in the morning or during the night
Isolated	Occasional episodes with no other sleep disorder
Recurrent	Repeated episodes over time, which are worth raising with a doctor

Sleep paralysis causes and triggers

There is rarely a single cause, but certain factors come up again and again:

• Too little sleep, or a run of short nights
• An irregular schedule, including shift work and jet lag
• Stress and anxiety, which can unsettle the way sleep stages flow into one another
• Sleeping on the back, the position many people report for their episodes
• Other sleep conditions, such as narcolepsy or obstructive sleep apnoea
• Some medicines, alcohol or other substances that alter sleep patterns

It can also run in families, and plenty of people have one or two episodes in their lives with no obvious trigger at all. First episodes often happen in the teenage years or early adulthood.

How to stop sleep paralysis coming back

Nothing guarantees it will never happen again, but steadier sleep makes episodes less likely for many people.

1. Keep regular sleep and wake times, weekends included.
2. Give yourself enough time in bed for a full night's sleep.
3. If episodes tend to happen on your back, try sleeping on your side; a pillow tucked behind you can help you stay there.
4. Build a calming wind-down routine. The guide to how long it should take to fall asleep has practical ideas.
5. Cut back on late alcohol and heavy meals close to bedtime.
6. Find a daytime outlet for stress, such as a walk, writing worries down or talking to someone you trust.

During an episode

Understanding what is going on can take some of the fear out of it. These steps help some people:

• Remind yourself that the feeling is temporary and will pass.
• Focus on one very small movement, such as wiggling a finger or toe, or moving your eyes from side to side.
• Breathe slowly and evenly rather than fighting for a deep breath.
• If you share a bed, agree on a signal and ask your partner to touch your arm or say your name if they notice.

Related night-time experiences

Sleep paralysis belongs to a group of events that happen at the borders between sleep and waking. Talking in your sleep is another, usually harmless, example. The heavy, muddled feeling some people have just after waking is something else again, known as sleep inertia.

Questions people ask

Is sleep paralysis dangerous?

The episodes themselves are not thought to cause physical harm. The main problems are the distress they bring and, for some people, anxiety about going to sleep.

Can you die from sleep paralysis?

No. However alarming the chest pressure feels, breathing continues and the episode ends on its own.

Why does it feel like someone is in the room?

Dream activity can spill over into waking awareness, so the brain fills the moment with images, sounds or a sense of presence that feel very real.

When to talk to a doctor

Speak to a GP if episodes are frequent, make you anxious about going to bed, or come with strong daytime sleepiness, falling asleep suddenly during the day, or sudden muscle weakness when you laugh or feel a strong emotion. These can point to a sleep disorder that may need assessment. A sleep diary helps: note bedtimes, wake times, naps, caffeine and alcohol, and when episodes happen, and take it along to the appointment.