Have you ever woken up in the middle of the night and found yourself partly conscious, yet unable to move? Perhaps you feel tightness in your chest, a sense of heaviness, or have trouble breathing? Maybe you notice voices nearby and then a dark figure comes toward you. You try to call out for help, but nothing comes out! While this can be a terrifying experience, it is a relatively common phenomenon known as sleep paralysis.

What is sleep paralysis?

When we fall into REM sleep, which is when we tend to dream the most, nature protects us from acting out our dreams by temporarily paralyzing voluntary muscles, a completely normal event called sleep atonia. Your body basically turns into a limp rag doll. Studies in rats have found that the neurotransmitters gamma-aminobutyric acid (GABA) and glycine turn off the brain cells that allow muscles to be active, initiating atonia. This is the neuro-biological basis of the atonia.

In many ways, sleep paralysis is an inappropriate relationship to sleep atonia, and occurs in an out-of-phase REM sequence. If you become conscious before the REM cycle is finished, which is when your body is still paralyzed, the result is the often unsettling experience of sleep paralysis. In other words, you’re partly awake when you’re not supposed to be, experiencing the atonia when you’re normally sleeping through it. It’s an indication that your body is not moving smoothly through the stages of sleep. Not knowing what’s going on is what transforms this normally smooth ride into a bumpy one.

Who tends to experience sleep paralysis?

Sleep paralysis tends to occur in those suffering from narcolepsy, sleep apnea, or other disorders which disrupts normal sleep patterns. But it can occur in anyone. It also tends to occur during the pre and post sleep states called hypnogogic and hypnopompic respectively. This is when I tend to experience it. (Hypnos is the Greek god of sleep, and “hypnogogic” means “leading to the god of sleep,” while “hypnopompic” means “leading away from the god of sleep.”) Up to 40% of people may develop sleep paralysis, which means they will experience it on a more consistent basis. It’s often first noticed in the teenage years, but anyone at any age can experience it.

What are the factors linked to sleep paralysis?

Sleeping on your back has been shown to increase the experience, as well as disruptions in your normal sleep patterns. This means jet-lag and other disruptors (like alcohol) can trigger it. Lack of sleep is also implicated, and conditions like stress or bipolar disorder are common contributors. Substance abuse, and certain medications, such as those used to treat ADHD, seem to facilitate the experience.

What is the best treatment?

Knowledge is the best cure for this one. Just knowing that sleep atonia is completely natural will keep you from freaking out when you experience it. Before I knew about it, I was totally upset by the event, thinking I was about to suffocate or even die. Now I experience sleep paralysis with a sense of fascination, curiosity, and even appreciation. “How amazing that mother nature came up with this remarkable form of protection!” (A protection that sometimes fails, as in REM behavioral sleep disorder, which we’ll explore in a future post.)

You can lessen your chances of experiencing sleep paralysis by improving sleep hygiene, which I’ll also cover in upcoming posts. Make sure you get enough sleep, and if you have disruptive sleep disorders, like narcolepsy or sleep apnea, get those treated. And do what you can to reduce stress, especially before bed. This is where evening meditation just before sleep can really help. You can also try new sleep positions, like sleeping more on your side (which also helps with reducing snoring). See your medical doctor, why may refer you to a sleep doctor, if you find that sleep paralysis regularly prevents a good night’s sleep.

Is sleep paralysis ever dangerous?

Sleep paralysis only becomes a problem if it routinely disrupts your sleep. It only becomes a serious problem if you totally misinterpret the experience, and juxtapose it with the power of belief. This is where sleep paralysis gets incredibly interesting. We know about the power of belief through things like the placebo effect, which is very common. What is not so common is the nocebo effect, which is when beliefs can harm — or even kill. (For more on the power of belief, see Placebo Nation: Just Believe, by Sharon Begley.

The medical anthropologist Shelly Adler describes the negative power of belief in her book, Sleep Paralysis: Night-mares, Nocebos, and the Mind Body Connection. Adler solved a twenty-five year old medical mystery that killed 117 healthy Hmong men. She was researching the phenomenon of “nocturnal pressing spirit attacks,” or what we know as sleep paralysis.

In traditional cultures, sleep paralysis is frequently associated with nocturnal evil. In China this paralysis is called bei gui ya (“held by a ghost”), Hungarians refer to it is boszorkany-nyomas (“witches’ pressure”), and Indonesians call it digeunton (“pressed on”). In Newfoundland, the spirit that comes during sleep paralysis is called the Old Hag, and the experience is referred to as a grog, or “hag ridden.” The Dutch call the presence of the Old Hag nachtmerrie, the “night-mare,” where the “mare” comes from the German mahr or Old Norse mara, which denoted a supernatural being that “lay on people’s chests, suffocating them.”

The Hmong men were displaced from their homeland in Laos, eventually settling in America. Over the course of several years, these sturdy young men started dying in their sleep from a mysterious illness. Doctors named this enigmatic killer sudden unexpected nocturnal death syndrome, or SUNDS.

Sleep paralysis and the nocebo effect

Through her cultural and epidemiological study, Adler determined that these men were killed by their belief in spirits. When these men experienced sleep paralysis, instead of understanding the harmless nature of this experience, they believed they were being assaulted by harmful spirits because of their sloppy spiritual worship. For a number of reasons, the displaced Hmong were unable to worship properly, and as one man explained to Adler, “When the Hmong don’t worship properly, do not perform the religious ritual properly or forget to sacrifice or whatever, then the ancestor spirits or the village spirits do not want to guard them. That’s why the evil spirit is able to come and get them.”

Adler coined the term “local biology,” and writes, “Since meaning has biological consequences, and meanings vary across cultures, biology can operate differently in different contexts. In other words, biology is ‘local’ — the ‘same’ biological processes in different places have different ‘effects’ on people.” In other words, the mind directly affects biology, or physical reality.[1]

For a summary of the Hmong event, See The Dark Side of the Placebo Effect: When Intense Belief Kills, by Alexis C. Madrigal, The Atlantic Sept. 14, 2011.

[1]Anthropologists have shown that sensory perception is also culturally specific. “More and more are willing to argue that sensory perception is as much about the cultural training of attention as it is about biological capacity,” says Stanford anthropologist T.M. Luhrmann (Can’t Place that Smell? You Must be American, by T.M. Luhrmann, New York Times, Sunday Sept 7, 2014.) For example, Americans are really bad at odor identification, while the Jahai, rain-forest dwellers on the Malay Peninsula were found to be really good. Different cultures can literally show you how to sense your world differently.