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12 Totally Weird Things Your Body Does Overnight

Experts explain the bizarre, sometimes gross and very common body functions we wake up to.

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body does overnight | woman holding a glass of the water

Dry mouth

Do you often wake up feeling parched even though you drank more than enough water the day before? When we sleep, we don’t produce as much saliva in our mouths, so we naturally wake up with a drier mouth than we went to sleep with, explains Gina Sam, MD, a gastroenterologist in New York City.

Although this sleep side effect is perfectly normal, you can try to avoid it by not using mouthwash containing alcohol, which can dry out your mouth. Also, keeping a glass of water nearby for when you wake up with dry mouth can provide some relief.

Morning breath

Bad breath can happen anytime thanks to the hundreds of types of bad breath-causing bacteria that naturally live in your mouth. “What’s known as ‘morning breath’ is caused by microbes that interact with the proteins in saliva which result in the production of volatile sulfur compounds that smell bad,” says Albert Wu, MD, director of the Center for Health Services and Outcomes Research at Johns Hopkins School of Public Health in Baltimore. Blame the “decreased production of saliva, which occurs when we are sleeping.” Among the factors that can exacerbate the problem: “Breathing through your mouth, which causes dryness, cavities, gum disease, and tobacco,” adds Dr. Wu. Good oral hygiene is key, especially before bed.

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body does overnight | stomach pains

Gas

When you’re sleeping, your energy production is reduced, which means your body is able to attend to other tasks, like digestion. “Lying down allows the intestinal gas that’s produced all the time to pool in the large intestine,” says Dr. Wu. “It is then released all at once when you change position, while getting up the result can be morning flatulence or ‘the wake-up farts.'” (Here’s what to do if you can’t stop passing gas.)

Puffy eyes

You may not realize it but every time you blink you’re helping flush out the excess mucus and irritants from your eyes. When you’re sleeping, that doesn’t happen. “During sleep when the eyes are kept shut, the film of tears that covers the eyes stagnate and change in composition,” says Dr. Wu. “More white blood cells are recruited, along with other inflammatory factors.  This leads to more blood flow, redness, and even a pus-like discharge first thing in the morning.”

While some puffiness is normal, excess salt and caffeine, not enough water, and being stressed can exacerbate the problem. Try splashing cold water on your face first thing in the morning to reduce the swelling.

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body does overnight | deodorant

Body odour

Despite your best efforts and religious application of deodorant, it’s perfectly normal to wake up smelly, especially in the underarm area. “This can be the result of bacteria on the skin and perspiration caused by elevated body temperature due to an overly warm room or too many blankets,” says Dr. Wu. “It can also be caused by diseases or conditions like hyperthyroidism or hypoglycemia.”

Drinking plenty of water and eating a whole-food, plant-based diet can dramatically reduce morning body odour.

Dark urine

Despite your level of hydration, you probably wake up with darker-than-normal pee. This is because your kidneys have been at rest (so to speak) for so long, according to Dr. Sam. The kidney output slows down at night and you produce less urine. “Your kidneys are part of the renal system, or urinary tract, along with the ureters, bladder, and the urethra. So if they are resting, your urine is concentrated, and therefore darker in colour,” she explains.

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body does overnight | toilet paper roll

Large bowel movements

If your morning poops scale on the large side, it’s due to all that digesting your body was doing while you were in REM sleep. “The contractions in the colon are highest in the morning, and this is when most people have a large bowel movement to get rid of the stool from digested food overnight,” says Dr. Sam. (Plus, don’t miss these explanations for every odd sound your body makes.)

Cracked corners of the mouth

Waking up with sore, cracked sides of the mouth not only is common but also can be rather uncomfortable if it happens nearly every morning. “When you sleep, saliva builds up at the corners of the mouth and can start to break down this delicate skin,” says Erum Ilyas, MD, a dermatologist at Montgomery Dermatology. “If this goes on long enough, a yeast infection can develop called perleche.”

If you are a mouth breather or have a cold, she recommends applying Vaseline or Aquaphor to the corners of your mouth before bedtime. This can serve as a barrier to protect your skin from breaking down and getting irritated.

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body does overnight | woman sore neck

Muscle cramps and stiffness

You don’t have to work out intensely the night before to wake up feeling as if you hiked a mountain. Stiff joints and crampy muscles in the morning have a lot to do with circulation. “As you begin to move around, blood and oxygen are diverted from your digestive tract and vital organs to meet the demands of your muscles,” says chiropractor Lev Kalika, DC, owner of New York Dynamic Neuromuscular Rehabilitation and Physical Therapy in New York City. “Poor sleeping posture, trigger points in your muscles, poor cardiovascular fitness, and dehydration can all contribute to morning muscle stiffness.”

Eye boogers

Waking up and having to clean out your eyes is part of most of our morning routines. Some call it “getting the sleep out of your eyes.” It’s perfectly normal, but definitely a pesky task.

“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 explains. “Washing your face with a gentle cleanser or Johnson’s No More Tears Baby Shampoo can help remove this.”

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body does overnight | headache

Painful jaw or headache

If you grind your teeth at night, you probably wake up with a painful jaw or even a headache. “When you grind your teeth at night, your jaw muscles never have a chance to relax, and you may develop trigger points that cause pain and dysfunction,” says Kalika.

The best thing you can do to combat this side effect is to de-stress as much as possible. “Stretching, deep breathing, meditating, and relaxing in an Epsom salt bath before bed will help you sleep better so you wake up refreshed and better able to manage stress,” Kalika suggests.

Greasy skin

Washing your face in the morning might seem silly if you washed it right before you went to bed, but it’s for a purpose. “At night our oil glands can be active and leave a layer of ‘grease’ on our skin first thing in the morning,” Dr. Ilyas says. “It helps to stick with gentle cleansers and avoid overly harsh or abrasive ones at night that can cause your skin to overproduce oil.”

Next, check out these strange body facts you’ve always wondered about.