Linda Rodriguez McRobbie

The Night Hag and other terrors of sleep

“The Nightmare” by Henry Fuseli is thought to be a depiction of sleep paralysis perceived as a demonic visitation.
“The Nightmare” by Henry Fuseli is thought to be a depiction of sleep paralysis perceived as a demonic visitation.Wikicommons

Brian Sharpless woke up in the middle of the night. He’d expected that. He and his girlfriend were jetlagged, their sleep rhythms completely off. He laid there, trying to think sleepy thoughts. And then it happened.

My bedroom door slowly swings open,” he recalled. “Then I see a black face, like a completely covered ninja face with red eyes. The face comes through the door and there’s an elongated neck, like a giraffe.” He tried to get away as this face got closer and closer, but he couldn’t even breathe.

It could have been terrifying. Except that Sharpless is one of the world’s leading researchers on strange sleep phenomena. “I think, ‘My God, I’m having sleep paralysis!’” he said, laughing. “It disappeared the moment I was able to move again.”

At the time of his first and only experience with sleep paralysis, Sharpless, a clinical psychologist, had been studying the phenomenon for eight years. He knew what people in more than 100 different cultures call sleep paralysis, this sudden waking with an inability to move, the feeling that something is suffocating you, and visions of terrible things coming to get you.

In Iran, it would have been the “bakhtak,” a kind of spirit that perches on the chest. In Japan, “kanashibari,” the sensation of being bound by invisible metal for centuries attributed to the stifling presence of ghosts. In Newfoundland and some places in the American South, it’s the “Night Hag,” a witch who sits on the dreamer’s chest. When you woke in the morning, tired and worn out, you might have described yourself as “hag-rid”, or ridden by the Hag. (This is one proposed etymology for the word “haggard.”)


This experience was what was originally meant by the word “nightmare.”

The core features are similar across time and place, but the actual hallucinations are partially dictated by the culture. For example, Americas and Britons are more likely to explain an episode of sleep paralysis as alien abduction. In August 2016, a Moscow woman called police in terror, claiming that she’d just been attacked by a Pokemon in her bed as her boyfriend slept on unaware next to her.


Sharpless describes sleep paralysis as “a strange blip in your sleep cycle where you’ve had REM sleep imposed over wakefulness.” In normal REM sleep, the brain shuts down voluntary muscle movement, to keep the dreamer from acting out the dream.

In an episode of sleep paralysis, however, that shut down is in effect while the dreamer is still transitioning into wakefulness. The result is that the individual experiences dream-like hallucinations coupled with an inability to move, often attended by sheer terror.

Sharpless and his colleagues have found that nearly 8 percent of the general population, nearly 29 percent of students, and 32 percent of psychiatric patients had experienced at least one episode of sleep paralysis in their lives.

Sleep paralysis is just one of a cluster of sleep-related disorders under the umbrella term parasomnias. These also include sleepwalking, which affects about 3.6 percent of the US population, according to a 2012 study; sleep talking, which affects about 5 percent of the adult population; sleep-related hallucinations, both in the hypnagogic (as you’re falling asleep) and hypnopompic (waking from sleep) stages; and the fantastically-named exploding head syndrome.

Sharpless is also an expert in exploding head syndrome, which affects as much as 10 percent of the general population at least once: As you’re just falling into sleep, you hear a loud bang, like a gunshot or a firework, sometimes accompanied by a flash of light. You are the only one, however, who heard anything at all. His research suggests that it’s a malfunction of the normal progress into sleep, in which the brain settles into slow wave activity. Instead of shutting down, however, exploding head syndrome “causes them to fire all at once.”


What some of these parasomnias have in common is an overlapping, or a mismatch, of dream and waking states. For the most part, our waking state is biochemically, neurologically different from our sleeping state. Occasionally, those states are porous, and in the areas between, strange things happen.

Linda Rodriguez McRobbie is a freelance writer.