What Causes Sleep Paralysis?

Sleep paralysis is the feeling of not being able to move while you are in the hazy in between world of consciousness and sleeping, but being unable to move. It’s a scary moment, and one that feels like it might never end.

So what causes sleep paralysis?

The good news is that it’s probably not as serious as it seems. Sleep scientists have found that, in most cases, sleep paralysis is just a sign that your body is not moving well through its sleep stages. It is only rarely that sleep paralysis is linked to underlying psychiatric problems.

There are two main times when sleep paralysis can occur: When it happens while you are falling asleep, it’s called hypnagogic sleep paralysis. Conversely, if it happens as you are waking up, it’s called hypnopompic sleep paralysis. But what causes sleep paralysis?

During sleep, your body alternates between REM (rapid eye movement) and NREM (non-rapid eye movement) sleep. Each cycle lasts 90 minutes. NREM sleep occurs first and takes up most of your body’s sleep time. During NREM sleep, your body relaxes itself and restores crucial enzymes it may need.

At the end of NREM, your sleep transitions into the REM cycle. This is when dreams occur, but the rest of your body remains very relaxed. This is when sleep paralysis can occur. Your muscles are unable to move during REM sleep, so if you awaken before the REM cycle has finished, you may experience the symptoms of sleep paralysis. Now you know what causes sleep paralysis. It’s such a normal experience that four out of ten Americans will experience it in their lifetime.

While it can be scary, know that it’s completely normal and you are not alone.