So THAT’S Why Your Mouth Opens When You Fall Asleep

Show of hands if you’ve ever woken up to your mouth wide open, throat as dry as the Sahara and a puddle of drool on your pillow.

You probably blame gravity and mosey on with your day — but if your mouth morphing into a drawbridge is more the norm than the exception, what you might actually be dealing with is a case of chronic mouth breathing.

Besides dry mouth and drool stains, other indicators include an ongoing sore or scratchy throat, hoarseness, bad breath, morning headaches, dark circles and feeling super tired despite getting a full night’s sleep.

“Even though there are many different causes of these symptoms, a combination of them increases the likelihood a person is chronically breathing through their mouth at night,” Dr. Charles Ebert Jr., director of neurorhinology and medical director of otolaryngic allergy services at UNC School of Medicine in North Carolina, told HuffPost.

As for why it happens, that depends on the person. You might breathe through your mouth at night simply out of habit — or your body might be sending up a flare that something’s off.

As you doze off, your face muscles gradually relax, giving your mouth free rein to drop open.

“Mouth breathing can happen at any time in the night, but is most common in deeper sleep stages, where people have less control over the muscles in the upper airway,” Dr. Christine DeMason, assistant professor of otolaryngology at the University of North Carolina School of Medicine, told HuffPost.

Your mouth being open during snoozefests doesn’t automatically lead to mouth breathing, though. In play is usually a one-two punch of gravity doing its thing and an increase in nasal resistance — where an underlying obstruction makes breathing through your nose a grind, so the body switches to mouth-breathing mode in an attempt to improve airflow.

Some underlying obstructions are temporary, like nasal congestion or blockages from allergies or colds. Certain medications can also cause congestion, Ebert said, including blood pressure medications, antidepressants and NSAIDs.

Other obstructions are anatomical and therefore trickier to combat solo, such as a deviated septum, nasal polyps or enlarged tonsils.

Another culprit is sleep-disordered breathing, or SDB, a cluster of conditions characterized by abnormal breathing patterns during sleep (think: snoring, sleep apnea).

“In general, SDB is due to some combination of obstruction and other physiological processes that either happen too slowly, too irregularly or fail to happen during sleep,” Dr. Mitchell Levine, associate professor of orthodontics at St. Louis University and president of the American Academy of Dental Sleep Medicine, told HuffPost.

You’re even more prone to mouth breathing at night if you sleep on your back: The position allows your tongue and palate to fall back more into the throat, ultimately narrowing your airway, DeMason said.

Having a nightcap before bed can also cause relaxation of the airway muscles, further exacerbating the potential for your mouth to open and your upper airway to collapse during sleep. Smoking too can lead to chronic mouth breathing because it causes inflammation of the nasal cavity, Ebert said.

“There’s not a lot of evidence that mouth breathing in and of itself causes significant harm,” Dr. Chris Winter, neurologist and sleep expert for Mattress Firm, told HuffPost.

It’s more likely that chronic mouth breathing creates a domino effect within the body that can encourage certain health complications to manifest over time, the exact pathways of which experts are still working to untangle.

Dry mouth from lack of saliva flow, for instance, can cause bad breath, cavities and gum disease, DeMason said. Without saliva to neutralize the acids produced by bacteria in the mouth, it leaves you more exposed to microbes that can multiply and lead to inflammation, infections and diseases in other parts of the body, including endocarditis (a type of heart infection) and cardiovascular disease, according to the Mayo Clinic.

There are also important perks to breathing through the nose that you miss out on when you breathe through your mouth: “Nasal breathing allows for filtering, heating and humidifying of the air,” Ebert said. “This reduces the risk of infection, moistens the airway and improves oxygen circulation.”

As an added bonus, the nose produces nitric oxide, a stimulant of the cardiovascular and immune systems, according to the Mayo Clinic.

Nitric oxide is picked up and transported throughout the body by breathing through the nose, dilating (widening) blood vessels and maximizing oxygen absorption by your organs and tissues. “The mouth doesn’t have these properties,” Ebert said.

Because chronic mouth breathing leads to narrowing of the airway, DeMason said, it can itself be a cause of sleep-disordered breathing and worsen the severity of underlying sleep disorders, such as obstructive sleep apnea.

To top it off, the restorative tasks accomplished by the body during sleep — healing and repairing the heart and blood vessels, balancing hormones, strengthening the body’s resolve to fend off germs and illnesses — are perpetually disrupted by chronic mouth breathing.

All of this can add up to the body becoming sleep deficient, increasing your risk of health problems like heart disease, high blood pressure and stroke, according to the National Heart, Lung and Blood Institute.

Obviously, the best way to stop sleeping with your mouth open is to find and treat the cause, such as blockages and underlying structural issues. Possible treatment options include:

“A lot of the time, mouth breathing can be a result of a nasal blockage,” Levine said. “Trying a saline spray, neti pot or allergy medication can often relieve nasal pressure and open up your nasal airways for easier nose breathing at night.” (Ditto nasal strips applied to the bridge of the nose.)

Nixing back-sleeping from your repertoire or propping your head up with pillows may help open the nasal airway and reduce mouth breathing. “Adjustable bases are also a great way to help elevate your head,” Winter said.

“If a person’s mouth breathing is habitual, some retraining exercises can help,” DeMason said. One option is myofunctional therapy, which is basically a workout program for your mouth, tongue and facial muscles.

Exercises a myofunctional therapist might assign you include:

• Pronouncing vowel sounds, either continuously or intermittently.
• Pressing the entire tongue against the hard and soft palate, then forcing the tongue onto the floor of the mouth.
• Blowing into a party horn.

Bonus: Research suggests these exercises can reduce SDB by encouraging the body to maintain an open airway during sleep.

These options shouldn’t be considered unless you’ve gone to a specialist to determine exactly what’s happening from a sleep and breathing perspective, Winter said. When there’s an underlying issue obstructing your ability to breathe through your nose during sleep, restricting your body’s only way of compensating is straight-up dangerous.

“One of the therapies to managing SDB is to minimize or reduce the impact of the obstructive tissue,” Levine said. “The soft palate is a key area of obstruction.” In obstructive sleep apnea, for example, the soft tissue collapses during sleep and blocks the airway.

Oral appliances (custom made by a dentist trained in dental sleep medicine) are designed to both “stiffen the muscles most likely to collapse and make the collapse less likely to occur by modifying anatomical structures,” Levine said.

“If it turns out someone has obstructive sleep apnea, a doctor will most likely have them wear a face mask appliance at night called continuous positive air pressure therapy, or CPAP,” Winter said. “The pressure of the air from the mask helps keep your airways open and prevents collapse or blockage.”

Structural issues and blockages, like a deviated septum, nasal polyps or enlarged tonsils, may require surgery to reduce nasal resistance, DeMason said.

If you’ve exhausted all over-the-counter options available to curb chronic mouth breathing and restful nights of sleep are still MIA, it’s likely time to consult a doctor, such as an ENT or sleep specialist, who can customize a treatment plan for you.