‘Mostly Benign’: Sleep Paralysis Demons Explained

The menacing shadowy figure that perches upon your chest making it hard to breathe and rendering you paralyzed for a few moments between sleeping and waking probably isn’t a nightmare come to life or a phantom that bubbled up from the underworld.

It’s more likely to be a hallucination that happens along with sleep paralysis, a largely harmless phenomenon that Katherine Green, MD, medical director of the University of Colorado Sleep Center, says happens to as many as 70% of people at some point in their life.

“Many people have this experience and while it’s mostly benign, it can understandably be frightening,” says Green, who is also an associate professor of otolaryngology at the CU Anschutz School of Medicine.

Records go back more than 300 years describing similar sleep paralysis experiences to what people report today. In 1664, a Dutch physician’s collection of case histories included the earliest known clinical description of sleep paralysis — writing that a female patient sometimes believed “the devil lay upon her and held her down” and could hardly speak or breathe while she “was in that strife”— and in 1781, Swiss artist Henry Fuseli painted “The Nightmare,” a famous depiction of what it’s like to experience a sleep paralysis demon, sometimes called an incubus in folklore. Historians believe the painting was inspired by Fuseli’s own experiences with “waking nightmares.”

We spoke with Green about the medical aspects of sleep paralysis, what’s happening in the body and brain, and what to do to lessen the anxiety that sometimes accompanies these chilling encounters.

What exactly is sleep paralysis and why does it happen?

Sleep paralysis itself is not an abnormal thing and it’s not always a sign of an underlying condition or a disorder. Fundamentally, sleep paralysis happens because of what our body does during REM sleep. During our dream sleep, or REM sleep, our brain disconnects from our muscles. I describe this to patients as a sort of safety mechanism. We have paralysis of our major voluntary muscles so we don’t act out our dreams – that would not be safe.

Sleep paralysis is a phenomenon of being either awakened abnormally or falling asleep into dream sleep where our brain is in dream sleep mode, so our brain is still in that REM sleep mode, but we have woken up. This sometimes creates a lag between when your brain wakes up and when that muscle connection returns.

How long does this typically last?

Only a few moments, but that can feel like a long time when you’re not able to move and in turn experience anxiety about what’s happening.

Lots of people report hallucinations along with the paralysis. What causes that?

It’s just the transition from the dream state to wakefulness. Some people don’t experience that piece, but for those that do, it’s a transitional hallucination that resolves along with the paralysis. It’s not pathologic, or concerning, or paranormal. It’s often the brain overlaying a story on top of the experience.

If somebody experiences sleep paralysis a lot, what should they do?

If this is something that happens multiple nights a week, or even multiple times a month, and it disturbs your sleep or you find that you are tired during the day or your sleep is not restorative, I think it is always a symptom that is worth mentioning to your doctor.

A lot of times, just the reassurance that, yes, this is a normal phenomenon for a lot of people and isn't necessarily pathologic, is helpful so that then when and if those episodes do happen, there's not that degree of panic or anxiety that there's something wrong.

However, sleep paralysis can be a symptom of various sleep disorders that cause dream sleep to be more fragmented. Most of us don’t wake up very often from a REM cycle and when we do our sleep quality is being disrupted. Conditions like narcolepsy and obstructed sleep apnea can cause sleep paralysis to happen much more frequently. In that case, you may be referred to a sleep specialist who can help treat the underlying condition.

Do you have any advice on how to cope during those few moments of confusion or terror with sleep paralysis?

Give your brain a couple of second to catch up and fully wake up and know that these episodes are short lived. I find that for a lot of patients, just knowing that it is a phenomenon that we have a good explanation for and that it is part of a normal sleep physiology for those muscles to be paralyzed during our dream helps. Try to take a couple of deep breaths and ride out those five to 10 seconds.