Sleep Paralysis: Symptoms, Types, and Effects Explained

Many people have heard of insomnia or sleepwalking, but not many know about a strange phenomenon known as sleep paralysis. This condition can be caused by one of several sleep disorders, but it can also be related to other medical conditions. If you have ever experienced sleep paralysis disorder, it may help you to learn more about it and understand why it happens.

Definition of Sleep Paralysis

If you have ever experienced paralysis in sleep, you might find it difficult to define sleep paralysis in terms others can understand. So what is sleep paralysis? Stanford University’s sleep paralysis definition says that this condition is a temporary inability to perform voluntary movements after falling asleep or upon waking up from sleep. Other terms for this temporary paralysis during sleep include familial sleep paralysis, isolated sleep paralysis, hypnagogic paralysis, predormital sleep paralysis, hypnopompic sleep paralysis and postdormital paralysis.

Types of Sleep Paralysis

There are several types of sleep paralysis, each of which has different effects. The effects of this disorder also depend on individual circumstances and factors such as sleep quality and sleep schedule. Sleep paralysis that occurs at sleep onset is referred to as predormital sleep paralysis or hypnagogic sleep paralysis. If the episodes of paralysis occur upon awakening, the condition is referred to as postdormital sleep paralysis or hypnopompic sleep paralysis. Isolated sleep paralysis usually occurs during the first two hours of sleep, according to the National Institutes of Health MedlinePlus. Some people with this condition also have narcolepsy, but there are many people who do not. This type of sleep paralysis typically occurs more often in those with post-traumatic stress disorder, bipolar disorder, depression and anxiety disorders. If episodes persist, the condition is known as recurrent isolated sleep paralysis. Some people use the term “REM sleep paralysis,” but this is not actually the name of a condition. Experts believe that people use this term because sleep paralysis mimics the reduced muscle tone experienced during normal REM sleep.

How Does Sleep Paralysis Relate to Narcolepsy?

As mentioned earlier, some people with sleep paralysis also have narcolepsy. You may be wondering what sleep paralysis, narcolepsy and other sleep disorders have to do with each other. The narcolepsy-sleep paralysis connection starts in the brain. The brain contains glands that regulate the sleep cycle. In some people, the low muscle tone associated with REM (rapid eye movement) sleep occurs along with narcolepsy. This causes some narcoleptics to experience episodes of temporary paralysis.

Sleep Paralysis Symptoms

Paralysis during sleep has several telltale signs and symptoms. One of the most significant signs and symptoms of sleep paralysis is inability to move the arms, legs or trunk after falling asleep or upon waking. Those who experience paralysis in sleep may also find that they have temporary periods of skeletal muscle paralysis. Some people with sleep paralysis can’t breathe during these episodes. Researchers theorize that the chest muscles may become paralyzed, preventing the lungs from inflating and deflating properly. Some people with this condition may also have hallucinations or dreams that seem to be real.

Stanford University researchers report that one in five sleep paralysis sufferers indicate experiencing the hallucinations that are sometimes associated with this disorder. These hallucinations are almost always negative, often involving witches, goblins, criminals and other negative characters. The hallucinations are so life-like that these bad characters seem to interact directly with the person who has sleep paralysis. This makes it absolutely terrifying for some people to go to sleep, as someone in the middle of an episode is completely unable to talk, move or scream.

Sleep Paralysis Diagnosis

Sleep paralysis is diagnosed using polysomnography, also known as a sleep study. During a sleep study, machines record the physiological changes that occur while the patient is asleep. Since most people sleep at night, a sleep study usually requires staying overnight at a clinic or hospital. The machines used for the study record brain waves, eye movements, heart rhythm and muscle activity. They also monitor respiratory air flow and the amount of oxygen in the blood during sleep. In addition to these machines, a sleep study technician monitors the patient using a video monitor and computer screen that displays the polysomnography data. This test can help diagnose the suppression of skeletal muscle tone, which can indicate the presence of a paralysis sleep disorder.

Psychological Effects of Sleep Paralysis

Sleep paralysis does not just affect the body physically. It also has several psychological effects on those who have the disorder. People who experience paralysis upon awakening may have some awareness during sleep paralysis episodes. This can lead to feelings of fear and sleep paralysis anxiety. Those who feel like they can’t breathe during these episodes may suffer significant sleep paralysis stress. For those who experience frequent episodes, going to sleep may produce excessive anxiety and fear about how the disorder will affect them physically. Researchers from the University of Wisconsin School of Medicine and Public Health have even uncovered a link between sleep paralysis and depression. Mariana Szklo-Coxe led a team of researchers that found that people with sleep paralysis are often diagnosed with depressive disorders.

Researchers from the department of psychology at Penn State University agree with this assessment. They conducted a study to determine the prevalence of sleep paralysis in different populations. The researchers found that sleep paralysis is actually a common occurrence. They also indicated a need for further research on this disorder so people have improved access to resources that can help them cope. Interestingly, the Penn State researchers found that sleep paralysis is more common in students and people with psychological disorders than in the general population. This shows that there is a definite link between the mind and the body, especially when it comes to sleep disorders.

If you have ever experienced a temporary inability to move your trunk or limbs during sleep or upon waking up, consult your physician as soon as possible. Your doctor may refer you to a sleep specialist for a sleep study and additional diagnostic tests.

About Leigh Ann Morgan

I write about all sorts of things but ever since I completely got rid of my constant neck pain by finding the perfect pillow, I've started to learn as much as I can about sleep quality and sleep disorders.


  1. Hennessey says:

    Well, i’ve always been going to sleep late at night and having this sleeping paralysis to where i cant move my body or speak, but i can always wake myself out of it. Just a couple months ago my Mother experienced a Sleep Paralysis and was snapped out of it by my Dad, He said she was holding her arm up and grunting trying to call for his name. Last night March 25th i experienced myself suffocating in a dream and woke up out of breath. I dont know if that has anything to do with Sleep Paralysis but my friends think it is. I was told that most people dont have it bad but when you do, you can see things physically. Considering that i myself and my Mom have experienced this i was just wondering if this is actually Sleep Paralysis and if so will it be passed down to my generation ?

  2. Matthew Proctor says:

    It sounds like your Mother experienced sleep paralysis. I can’t say for sure because I’m not a sleep scientist but I think it’s a genetic thing so you might experience it as well eventually. Dreaming you’re suffocating sounds more like Sleep Apnea than sleep paralysis but I’m no doctor. The best thing you could do is go to see your doctor and ask them about your symptoms. They would be able to determine what it is you’re actually experiencing when you sleep.

    From my own personal experience, my mother, my brother, and me all experience sleep paralysis regularly so I have a feeling it’s genetic but that’s only anecdotal evidence at best. Even if it is passed down, there’s nothing to be afraid of. Sleep Paralysis isn’t dangerous, it’s just uncomfortable and a bit frightening.