Most of us never think about how we breathe at night. The nose does the job without a sound, and we only wake up long enough to roll over. Then one morning your mouth feels like sandpaper and you wonder what went wrong.
Habitual mouth breathing during sleep bypasses several things your nose quietly does for you. Nasal passages warm, humidify and filter the air before it reaches your lungs.
They also release a gas called nitric oxide that helps blood vessels relax. According to Cleveland Clinic pulmonologist Jason Turowski, this chemical is a vasodilator, meaning it opens up blood vessels and helps lower blood pressure.
The gas comes from the lining of the paranasal sinuses, the small air pockets around your nose. It is picked up on the way to the lungs when you breathe in through your nose. Mouth breathing skips the whole system.
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What mouth breathing at night does to your mouth
The clearest consequence shows up in the mouth itself. A small 2016 sleep study in the Journal of Oral Rehabilitation measured mouth pH overnight in 10 healthy volunteers wearing a nose clip.
During normal sleep the pH stayed around 7.0. During mouth breathing it dropped to 6.6 on average. The lowest readings fell to 3.6, well below the point where tooth enamel starts to dissolve.
The reason is simple. The mouth dries out and saliva can no longer buffer acid. Lead author Joanne Choi and colleagues at the University of Otago in New Zealand concluded that mouth breathing may be a causal factor for enamel erosion and cavities.
When mouth breathing points to sleep apnea
Interrupted sleep is the bigger worry. Mouth breathing often tracks with snoring and obstructive sleep apnea, in which the airway collapses repeatedly and oxygen levels dip.
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A clinical study in the Brazilian Journal of Otorhinolaryngology looked at 248 mouth-breathing children. It found that 42 percent had obstructive sleep apnea syndrome. Most of the rest were primary snorers.
Adults are not off the hook. If you consistently wake with a dry mouth, snore, or feel exhausted after a full night in bed, it is worth telling your doctor and asking whether a sleep study is appropriate.
The simplest fixes that often work
The options range from very simple to more involved.
Clear the nose first. Allergies, a deviated septum and chronic congestion push people toward mouth breathing. A short saline rinse, an antihistamine, or a nasal steroid spray prescribed by your doctor can restore a clear path overnight.
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Add moisture. A bedroom humidifier helps when dry heated air is part of the problem. A nasal strip, the sticky band that lifts the sides of the nose, can help when the obstruction is mechanical and mild.
Train the muscles. Mouth, tongue and throat exercises, known as myofunctional therapy, strengthen tissues that keep the airway open.
A Cochrane review from November 2020 pooled two trials of this therapy against sham treatment. It reduced the apnea-hypopnea index, a measure of breathing pauses per hour, by about 13 events on average. Daytime sleepiness probably improved too.
For loud snoring, witnessed breathing pauses or persistent daytime fatigue, a proper sleep study is the step that catches sleep apnea early. Many people never know they mouth breathe until a partner mentions it.
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A conversation with your dentist or doctor is the next practical step.
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This article is made and published by Mie Hermansen, who may have used AI in the preparation.