It was an otherwise normal morning. Like every other day, my clock radio came on and NPR started to filter through my sleep. My then-girlfriend was snoring beside me, my roommates were all tucked away in their beds (or in someone else's), and the world outside was just beginning to come to life. I was 20. But unlike every other morning for the preceding 20 years, I could not, for the life of me, move my body. Not a single part. Not my arms, not my legs, not my pinkie toe, not my eyelids—nothing. I was completely, utterly paralyzed. Even weirder, it felt like there was a weight on my chest, as though someone—or something—was sitting on me.
It was my deepest, darkest fear come to life: I was locked in. I panicked.
Unfortunately, panicking while you are paralyzed accomplishes nothing. My eyes still closed, I mentally willed my body to move.
C'mon, I thought. You can do this. Just a toe. You do it a million times a day. Move. Move. Mooooove.
I switched tactics, trying to will my girlfriend awake. If you would just shake my arm, I thought, this whole thing would go away. Wake up, wake up, wake up, I silently screamed, unable to form words, my hysteria rising by the second. Now was not the time for her to oversleep.
She did not wake up. For the next few minutes (or perhaps it was just a few seconds), I slipped in and out of consciousness, not sure if I was dreaming or if I was dead.
It was the most terrifying morning of my life.
I have repeated it hundreds of times since.
If this waking nightmare had happened for the first time now, I would just google it. Maybe something like: "Do I have a brain tumor?" But the first time was in the pre-Google era, back when we got our misinformation direct from other human beings. I started asking around. A waitress at the pizza joint where I worked had an answer.
"Oh, yeah," she said, sucking on a Pall Mall. "That's just a night hag."
According to my coworker, a night hag is the spirit of a restless woman who enters people's bedrooms at night and either sits on their chest or has sex with them, she couldn't remember which. I was pretty sure that I hadn't been molested by a phantom spirit while my girlfriend snoozed beside me, but there was definitely something on my chest. It had to be a night hag. Right?
Wrong. What I'd actually experienced, as I later learned, was called "sleep paralysis." There are tons of mythologies surrounding it. The night hag my friend referred to comes from Southern folklore, but in the Caribbean, it's called the Kokma. In Zanzibar, it's the Popo Bawa and it primarily goes for guys. In Chile, it's a deformed dwarf named Trauco. In Ecuador, it's also a dwarf, but one who likes hairy women. In India, the night hag is an angel. In Hungary, it's a chicken.
The earliest known mention of this creature, which is more commonly called the incubus (male) or the succubus (female), is on a stone tablet from 2400 BC known as the Sumerian King List. The text, which originated in Mesopotamia, refers to Gilgamesh, a demigod with superhuman strength, who was apparently the love child of a night hag and her sleeping lover/victim. Later, an incubus appears in Romeo and Juliet, where it impregnates maids, and again in The Nightmare, a dark red-and-orange oil painting by Swiss artist Henry Fuseli that depicts a woman, either sleeping or dead, with a ghoulish demon perched on top of her.
I know the feeling.
Despite all the stories humans have invented to explain this terrifying experience, the truth lies in the brain. During sleep, the body enters a phase called rapid eye movement, or REM, which is that deep-sleep state when dreams occur. In most people (those of us who don't sleepwalk), the brain stem essentially turns off the muscles during REM and we're completely unable to move. This prevents us from acting out our dreams (and likely saves us all a lot of embarrassment), but sometimes signals in the brain misfire and your mind wakes up before your body does. That's sleep paralysis.
Dr. Martha Billings, a sleep specialist at UW Medicine, refers to it as "the stage in between REM and wake," and she says her patients sometimes think they've had out-of-body experiences or were abducted by aliens. That's not as silly as it sounds: For some people, sleep paralysis is accompanied by vivid hallucinations. A friend of mine has this condition, and she described a recent experience: "I was 'awake,' paralyzed, and I hallucinated someone breaking into my room. I heard them jiggling the door, which was not locked, and then go to the kitchen, rummage through the flatware drawer, come back, and break the lock (again, it wasn't locked). Then three shadows burst into the room, stopped, and stared at me. Then they disappeared in front of my eyes and that was it. I spent the rest of the night googling schizophrenia."
She does not, as far as I know, have schizophrenia, but it's possible she doesn't get enough sleep. Billings says that sleep paralysis is more common in people who undersleep, as well as those with sleep apnea and narcolepsy. Studies have also shown that people with abnormally short REM cycles are more likely to experience sleep paralysis, as are those with panic disorders or post-traumatic stress disorder. And it's surprisingly common: Virginia Mason sleep specialist Dr. Brandon Peters-Mathews—who calls sleep paralysis a "mixed state of consciousness"—told me that an estimated 20 to 25 percent of the general population has experienced sleep paralysis at least once, and 5 percent experience it more often.
For those of us in this unlucky club, there is no cure, but there are things you can do to prevent it. Namely, practice good sleep hygiene: limit your naps, avoid caffeine at night, drink alcohol only in moderation, exercise, eat well, turn off your screens at least an hour before bed, and get plenty of natural light.
From my experience, this works. After years of off and on sleep paralysis, it's rare for me these days. Now I might get it once a year, maybe twice, and I suspect this is because I consciously developed a healthy sleep routine. Experience tells me that if I'm not careful about my sleep, my worst nightmare is just a few misfired synapses away. So now I drink decaf after noon, I've given up entirely on naps, and I get at least 8 to 16 hours of shut-eye every night. And on the rare occasion that I do wake up in the in-between, I do something that was unimaginable the first time it happened: I calm myself down. It's just a night hag, I tell myself. She won't hurt you. If I'm lucky, I fall right back asleep.