A few months ago, around 3am, I woke up and couldn’t move.

Not like when your arm falls asleep. I mean nothing. I couldn’t sit up. I couldn’t yell. And there was something in the corner of my room.

I couldn’t tell what it was. Just a shape. Dark. Standing there.

I don’t know how long it lasted. Eventually it stopped. I turned on every light and spent the rest of the night on my phone reading about sleep paralysis because I had no idea what had just happened.

Turns out, it’s really common. Around a third of people have had it at least once.

I didn’t know about the hallucinations part. I thought what I saw was just leftover dream stuff. But when I started reading other people’s accounts, the same things kept coming up. A presence in the corner. A feeling that you’re not alone. Breathing somewhere in the room that isn’t yours. Or the chest pressure version, like something is sitting on you, which also explains why breathing can feel strange during it. Some people float. Some feel the room tilt. Different details, but the same territory.

The history stuff is where I lost hours. Every culture seemed to have its own creature for this. England had the Night Hag, or the mare, which is where the word “nightmare” comes from. Japan has Kanashibari, meaning “bound in metal.” Brazil has the Pisadeira, a woman with long nails who walks on sleeping people. West Africa, the Caribbean, ancient China, the Islamic world, same experience, different name.

REM sleep, short for Rapid Eye Movement sleep, is the stage of sleep where most vivid dreaming happens. During REM sleep, your brain shuts down most of your muscles so you don’t act out your dreams. This happens every night, and usually you never notice it.

Except sometimes it doesn’t lift right away. Your brain wakes up first, but your body hasn’t caught up yet. So you’re just lying there. Awake. Can see the room. Can’t move. And your half-awake brain, running on fear, makes something up to explain what’s wrong. A shape. A presence. Something in the corner.

Knowing all this doesn’t help much when you’re in it. When you’re in it, it feels real.

After mine happened a couple more times, I got obsessed with figuring out the cause. I was sleeping badly, different times every night, maybe five hours on average, stressed. Apparently, when you’re underslept, your brain tries to catch up on REM sleep, which can make waking up out of it messier. Sleeping on your back also makes it more likely, which I’d never heard before but kept seeing it mentioned in other people’s experiences. I switched to my side and it helped. The alcohol thing surprised me too. A drink to wind down can suppress REM while it’s in your system, then cause a rebound around 2-3am, right when you’re more likely to wake up halfway. I was basically causing them without realizing it.

The fixes were boring. Consistent sleep schedule, I ignored this because it sounds like pamphlet advice, but it worked. Episodes dropped off fast. Pillow behind me so I can’t roll onto my back. Phone away before bed so my brain has time to slow down.

If it happens, don’t try to muscle through it. That usually makes it worse. Try moving one finger. Focus on breathing. Try to remember that you know what this is.

Some people realize, even while it’s happening, that they are in sleep paralysis. Instead of panicking, they stay calm and use that half-awake, half-dreaming state to enter a lucid dream, where they know they are dreaming and can sometimes control what happens.

I cannot do this.

I still think about that corner sometimes. What I was certain was standing in it.

All those people throughout history waking up paralyzed in the dark and putting a creature in the corner, they weren’t making it up. They just didn’t know what it was.

Had this happen to you? Reply and tell me what you saw. The range of things people describe is something I keep coming back to.