Sleep is a bit of a mysterious thing. And although you may notice your body has done some bizarre things by the time you wake up, it can be hard to understand exactly what happens to your body when you sleep. Luckily, doctors understand these processes so you can understand your body better.
The sleep cycles are different stages your body goes through when you sleep. Sleep architecture revolves around us going through 90 to 120 minutes cycles of stage one, then stage two, then stage three, then stage four, then REM sleep. Some stages are dream time, some are memory consolidation time, some are conflict resolution time. All throughout, your body is going through all sorts of processes that it doesn't go through during the day.
Some of the seemingly weird, or gross things that your body does when you sleep happen throughout every stage of your night's rest. Some things, however, happen only at certain points. When you wake up in the morning you may or may not even realize that these gross things were going on. The most common ones are perfectly natural and part of a healthy night's sleep, while the rare ones are a bit more unusual.
Here are eight seemingly gross things your body may do throughout your sleep cycle, according to experts.
1. Lose Fluid
If you've ever fogged up a window with your breath, you know that our bodies emanate moisture all the time. The same is true during your sleep.
"We all lose lots of fluid as we sleep," Leslie Fischer, founder of Sustainable Slumber says. "Some experts have estimated this to be about a liter a night! This is due to sweating and surprisingly, exhaling." So next time you wake up thirsty, know it's because you've been losing a bunch of moisture through your breath overnight.
2. Bad Breath
The Mean Girls trope of having really bad breath in the morning actually comes from a natural, but gross, part of the sleep cycle.
"Bad breath (halitosis) comes from mouth breathing that dries out our saliva," Dr. Honaker says. "This allows the release of bad smelling chemicals from the bacteria that colonize our mouth but do better in a wet saliva environment." This phenomenon explains why your breath may be perfectly fine in the daytime, but not-so-great at night.
3. "Exploding Head Syndrome"
While exploding head syndrome doesn't happen to everyone, it's an upsetting part of the sleep cycle to many.
"Exploding head syndrome is a rare but very real phenomenon that some people experience," Fischer says. "The name is pretty dramatic but this condition is characterized by hearing a loud sound, like a gunshot, when you are coming in and out of deep sleep." This condition may not be "gross" in the same way bad breath is, but it's definitely haunting and worth talking to your doctor about if you experience it.
4. Waking Up Quasi-Paralyzed
Another strange body phenomenon that happens when you're asleep is that you can end up temporarily losing control of your muscles.
"Your muscles (except for your eye muscles) are temporarily paralyzed so that you don’t act out your dreams," Dr. Melynda Barnes, associate clinical director at Ro. "Sometimes we wake up before the paralysis has worn off and we can feel the inability to move." So if you've ever felt your arm go completely limp when you wake up, it's just annoying, but totally normal.
5. Your Skin Gets Greasy
Another seemingly gross thing your body does at night is get a bit greasier than normal. This odd phenomenon happens as a result of common processes in your skin.
"At night our oil glands can be active and leave a layer of 'grease' on our skin first thing in the morning," Erum Ilyas, MD, MBE, FAAD, says. "Sometimes patients will even complain that their eyes 'burn' if they don’t wash their face." Making sure your nighttime skin routine is gentle, and not forgetting your morning routine, can help this not become a bigger problem.
6. Your Eyes Get Crusty
One of the most common gross nighttime things your body does is create dry eye mucus. Whatever you call it ("eye boogers," "crusties," "sleep") — it's just another natural part of the sleep process.
"Sometimes an accumulation of tears, mucus, and dead skin cells can build up along the eyelids and make them feel ‘crusty’ in the morning," Dr. Ilyas says. "Washing your face with a gentle cleanser or no more tears baby shampoo can help remove this." And while they may be annoying, crusty eyes are totally normal.
7. Your Mouth Can Get Dry And Crack
Natural sleep processes can cause dry, cracked corners of the mouth. Although it's quite uncomfortable, it's also really common.
"Patients will describe it as though they go to open their mouth to yawn and the corners of their mouth just crack or feel really sore," Dr. Ilyas says. This often happens from breathing with your mouth open, allowing saliva to build up in the corners of your mouth overnight. Wearing Vaseline on your lips to bed can help.
While nothing natural that your body does is truly "gross," there are a lot of little annoyances that happen throughout a good night's sleep. With a doctor's help, many of these things can be dealt with if they annoy you, but most are completely normal things your body does in order to get you through the night.