Sleep paralysis: What it is, why it happens and how to help prevent it

Someone is lying in bed, wide awake. But they can’t move or even speak. A heavy weight presses on their chest. Maybe they hear whispers or footsteps or see a shadow in the room. It’s terrifying, but it’s not supernatural. It’s sleep paralysis.

This medical condition affects millions of people worldwide. Although it feels like something out of a movie, it's actually a harmless and well-known sleep disorder.

This guide will break down what sleep paralysis really is, what causes it, and most importantly, how to help stop it from happening again.

In this article:

What is sleep paralysis?

Sleep paralysis is a temporary condition where a person is awake but unable to move or speak. During rapid eye movement (REM) sleep, the brain naturally paralyzes the body to prevent people from physically acting out their dreams. However, if the brain wakes up before the body does, a person can become mentally alert while still unable to move. This usually happens as someone is falling asleep or waking up.

The condition is fairly common and can affect anyone. Around 2 in 25 people will experience it at some point. It’s slightly more common in people assigned female at birth and typically begins in childhood, adolescence or early adulthood.

There are two main types of sleep paralysis:

• Isolated sleep paralysis: A single episode happening in an otherwise healthy person.
• Recurrent sleep paralysis: Having more than one episode over time. One study defines “recurrent” as at least two episodes within six months, especially if those episodes caused intense fear.

Sleep paralysis symptoms

The most common symptom of sleep paralysis is being awake but unable to move or speak. People can still breathe, think clearly and usually move their eyes. Along with this frozen feeling, many also experience:

• Hearing voices, murmurs, footsteps or buzzing
• Intense fear, panic or paranoia
• Sweating, headaches or muscle tension
• The sensation of being stuck between sleep and wakefulness

Hallucinations are also very common and tend to fall into three main types:

1. Intruder. Sensing a frightening presence in the room, which is often described as a shadowy figure, demon or alien.
2. Incubus. Feeling pressure on the chest or the sensation of being suffocated, held down or even choked. Some also report aggressive or sexual experiences, despite nothing physically happening.
3. Vestibular-motor (V-M). Feeling like floating, flying or having an out-of-body experience. Episodes usually last from a few seconds to about 20 minutes. On average, they’re around 6 minutes long — but in the moment, they can feel much more intense.

Why does sleep paralysis happen?

Let’s take a closer look at what happens during a sleep paralysis episode.

Inability to move

During REM sleep, the brain sends signals to temporarily paralyze the body’s muscles. This natural paralysis prevents people from physically acting out their dreams. Sleep paralysis occurs when the mind wakes up, but the body remains in a paralyzed state from sleep. This creates a brief period where a person is conscious but unable to move or speak.

Difficulty breathing

During sleep paralysis, the body's muscles stop working for a short time. This includes some of the muscles that help with breathing. But the main breathing muscle, called the diaphragm, still works just fine. As a result, people might feel like they're not getting enough air, even if they are.

Hallucinations

During sleep paralysis, the brain is still partly dreaming. This can make dream images mix with real thoughts. That’s why people might see or hear things that aren’t there, like shadows or strange sounds. Some scientists think a brain chemical called serotonin plays a role. It can affect how we see and feel things. A part of the brain that helps us understand what we see (the orbitofrontal cortex) may also be involved.

Pressure on the chest

Feeling chest pressure during sleep paralysis is actually a hallucination. But it helps to explain the hallucination on its own. During sleep paralysis, people often feel like something heavy is sitting on their chest. This happens because the brain relaxes most muscles during REM sleep. Some of these muscles help with breathing. Breathing becomes slower and weaker. The brain can get confused and turn that feeling into pressure. If someone feels scared, it can make the pressure seem even worse.

Panic

During sleep paralysis, people are unable to move or talk. Some might experience sensations of something watching them, or they might see scary creatures. These episodes can make them panic and feel afraid. The brain also becomes extra alert during REM sleep, which can make everything feel even scarier. That’s why sleep paralysis can feel so intense, even though it’s not actually dangerous.

What triggers sleep paralysis?

There’s no single cause of sleep paralysis. But physical, mental and lifestyle factors can make episodes more likely or frequent. Some of the most common conditions include:

Preventing and managing sleep paralysis

Most people with sleep paralysis don’t find it distressing enough to need medical help. A single episode is usually nothing to worry about. However, if episodes happen often and start to affect daily life, treatment might be a good idea. Now, these treatments can help reduce how often episodes occur. But once an episode starts, there is no proven way to stop it. The person simply must wait for it to pass.

Since there's no way to stop an episode once it starts, focusing on prevention is key. Sleep paralysis is often linked to poor sleep. One of the best things people can do is improve their daily sleep habits and routines.

Ten tips to try out are:

1. Go to bed and wake up at the same time every day, including weekends.
2. Aim for seven to nine hours of quality sleep each night.
3. Manage stress with relaxation techniques like meditation.
4. Get treated for other sleep issues, such as insomnia.
5. Keep the sleep environment dark, cool and quiet. 
6. Avoid stimulants like caffeine and alcohol in the evening and before bed.
7. Sleeping on the side and not on the back or stomach.
8. Using a comfortable mattress and pillow.
9. Avoiding screens (TV, phone, computer) for at least 30 minutes before bed.
10. Establish a relaxing bedtime routine.

In some cases, a health care provider may prescribe medication to help manage an underlying condition, such as anxiety.

Diagnosing sleep paralysis and when to seek help

Most of the time, sleep paralysis doesn’t need special tests or a diagnosis. A health care provider will simply ask questions or give a questionnaire to learn more about the episode. Also, people don’t need to hallucinate to be diagnosed with sleep paralysis. Anyone who feels scared during episodes or has them often should talk to their health care provider.

Key takeaways

Sleep paralysis is a common but scary experience. It happens when someone wakes up or falls asleep and can’t move or speak for a short time. People often feel pressure on their chest, panic or see things that aren’t actually there. Even though the episodes feel intense, they are not usually dangerous. Sleep paralysis is often linked to poor sleep, stress or other health issues. While it’s impossible to stop an episode once it starts, getting better sleep and managing stress can help prevent it.