5 Creepy Things Your Body Does When You Go to Sleep

5 Eye-Synced Erections

During a normal night’s sleep, a man will get erect five times, and these erections will coincide exactly with REM sleep, the parts of your sleep with rapid-eye movement. A lot of articles about this phenomenon, which is called nocturnal penile tumescence (NPT), refer to it as morning wood, but that’s misleading. Morning wood is our phrase for waking up with an erection. NPT happens repeatedly during the night, and we have no slang term for it — because we have little need for ever discussing it, because the sleeper isn’t even aware it happens. 

The sleeper is unaware of it, but we humans overall have known about the phenomenon for a long time. Presumably, various people who spent any amount of time close to a sleeping man noticed this, going back thousands of years. Scientists first documented it in the 1940s, before they’d documented REM sleep. Then they said to themselves, “Let’s see what else wiggles around several times a night,” discovered REM and uncovered the brain activity that’s responsible for both. 

We’ve since developed a working explanation of the purpose of sleep boners. They give the penis a periodic shot of oxygen and nutrients, we figured, which is a mechanism for ensuring the penis stays healthy. That sounds convincing enough, but like many explanations for weird body stuff, we came up with it just by asking ourselves, “Why might humans have evolved this?” We don’t truly know what purpose NPT serves, if any. We also have some reason to think it’s not really an evolved trait for exercising the penis like people say. 

For starters: It happens to women, too. It’s not quite as obvious with women — scientists had to get closer to observe it in female sleepers — but the sexes both experience periodic jumps in genital blood flow as the brain cycles when sleeping. Women don’t have the same risk as men do of erectile tissue getting replaced with collagen from disuse, so they can’t be getting nightly erections to prevent that, and maybe men don’t either. 

Instead, here’s what seems to be the truth: We all get signals from the parasympathetic nervous system engorging our naughty parts for 25 minutes every hour and a half, and those signals exist whether we’re awake or asleep. But while we’re awake, the brain sends other signals as necessary to keep that needless engorgement from happening. When we’re asleep? The safety’s off. We lose control.

4 Chemical-Induced Paralysis

So, that’s kind of unsettling — the idea that the body’s not acting on purpose but has just been let off the leash. But give us a second, and we’ll explain how the opposite is also unsettling.

You don’t move that much when you’re asleep. You change position every so often, but you don’t go doing jumping jacks. The reason for this appears to be obvious: You’re unconscious, so you aren’t choosing to move. But the real reason is more complicated than that. 

Your muscles move as they respond to all kinds of signals that come flying down your nerve fibers. They also respond to chemicals. If they find themselves flooded with γ-aminobutyric acid (GABA), your motoneurons — those are the nerve cells that worm into your muscles — shut down. 

When REM sleep kicks in, one section of your brain called the subcoeruleus nucleus gets to work. It squirts out GABA, which keeps most of your muscles from working. This results in atonia, or muscle paralysis. This is fairly important, because without it, your dreaming brain will send out messages telling your muscles it’s time to fight, and you’d get up and leap right out the window.

This is a fine enough system, most of the time. You don’t find it so fun, though, during those occasional times when you regain consciousness but your brain keeps pumping your muscles with GABA. We call that sleep paralysis. 

Or, worse, your brain may send out GABA at the wrong time, perhaps leading to sudden total paralysis in the middle of the day. This is called cataplexy and can result from strong excitement or fear. It can also result from intense laughter, so if you think our articles aren’t that funny lately, this is entirely for your protection.

3 Bug Orgies on Your Face

If you’re like 90 percent of humans, your face is covered in mites known as Demodex folliculorum. They live in your pores, which means they burrow into your cheeks, your forehead and the sides of your nose. They also might live in the hairs of your buttocks or pubic area, but they really enjoy spending time on your face. They can measure almost half a millimeter, which is pretty big, as microscopic stuff goes. And these aren’t germs — they’re animals.   

Sometimes, these mites cause skin conditions. Their burrowing leads to demodicosis, which makes you itch, but that’s usually only if you’ve already got something else wrong with your immune system. Rarely, they’ll go nuts, and you’ll lose your eyelashes. 

Most of the time, however, Demodex is harmless, or even beneficial. They produce digestive enzymes, which react with the sebum around your hair, releasing fatty acids that keep harmful bacteria from infecting us. Really, they’re nothing to worry about. Unless, of course, you find it worrying when intruders have sex on your face while you’re asleep. 

During the day, the mites are so deep in your pores that you can’t possibly remove them. At night, when you sleep, they emerge, and they mate. Then they head back into your pores to lay eggs. 

A couple million Demodex are on your skin right now, and each one has a two-week lifecycle. A conservative estimate therefore says that every night, your skin is the venue for 50,000 acts of copulation. Worse, consider this: No matter how much you object, during much of this time, you’re in a state of physical arousal. 

2 Hairs Mirroring Your Consciousness

How long do you personally sleep every night? Feel free to lie, because there’s surely no way for us to check whether you’re telling the truth. “I get by on five hours a night,” you might say, falsely. Or, if you do sleep just five hours (because of your issues), you might say, “I make it a point to get in a solid eight hours,” and we have no way of proving you wrong. 

Unless, that is, someone gets their hands on a few of your hairs. Then they could study those and uncover the truth. 

Your hair doesn’t grow continuously, the same amount every second. It has its own little cycle, controlled by the body’s circadian rhythm. For example, you’ve got this gene called CLOCK (“circadian locomotor output cycles kaput”) that controls your body’s daily clock, and was named by scientists who know how to have a good time. Your circadian rhythm, which genes like this handle, controls your sleep cycle and all the growth of your hair. 

It’s not just that you have a set cycle, and your sleep and hair both follow that. When you change how you sleep, this changes your circadian rhythm, and your hair growth consequently changes. To demonstrate this, scientists followed a bunch of workers who switched to night shifts. Their sleep schedules changed because of this (the workers’, not the scientists’ — well, maybe the scientists’, too). And the scientists could see resulting changes in the workers’ hair. 

So, never let scientists look at your hair. Never let witches do so either, as they can use your hairs to control you. 

1 Brainwashing

The brain, like almost every part of the body, has a network of blood vessels that bring in nutrients and ship out waste products. The brain doesn’t make direct contact with blood, however. It sits in a pool of cerebrospinal fluid, and this fluid has a whole separate circulatory system. 

Fluid flows into all the brain’s nooks and crannies, dragging out garbage like amyloid beta peptide, which would give you dementia if left on its own. We’re guessing you didn’t learn much about this circulation in school, because we only discovered this system in the last decade or so, and we’re still figuring out how it works.

Sleep is when this fluid really sloshes around. Blood flow to the brain drops, which makes sense, as your brain might not need the usual sort of fuel if you’re unconscious. In its place, but outside the blood vessels, extra cerebrospinal fluid sweeps in. The movement of blood in the arteries, low as it is, provides the force that gets this fluid oscillating. It works, note researchers, very much like the rinse cycle in a washing machine, using agitation to loosen gunk and take it away. Each rinse cycle of the brain takes 20 seconds. 

“Scientists don’t really know why we have to sleep,” we’ve told each other for many years. But thanks to new discoveries about these fluid movements (the “glymphatic system”), we might have finally figured out the answer: We sleep so we can be brainwashed. It fits nicely into the theory we’ve always had that sleep is when the brain undergoes maintenance, but now, we’re actually seeing what happens instead of just making guesses.

And if that’s what sleep is for, maybe we can figure out how to give you more of that. Instead of waiting for the brain to go into low-power mode so the arteries can work on that rinse cycle, we can fiddle around and make the fluid scrub you while you’re still awake. Maybe in the future, this can turbocharge everyone’s cleaning systems, preventing diseases like Alzheimer’s. 

Or maybe, once we figure out how to wash your brain during meals and when you’re watching TV, you’ll never need to sleep again. 

Follow Ryan Menezes on Twitter for more stuff no one should see.