Breathing through your mouth occasionally, especially during a cold, is common. However, regularly sleeping with your mouth open can contribute to disrupted sleep, morning throat irritation, bad breath and persistent dry mouth.
Because nighttime mouth breathing may be related to nasal congestion, allergies or a sleep disorder, identifying the underlying cause is an important step toward finding lasting relief.
Why does mouth breathing cause dry mouth?
Your nose helps warm, filter and humidify the air you breathe. When you breathe through your mouth, air moves directly across the oral tissues. This airflow can allow moisture to evaporate more quickly, leaving your mouth and throat feeling dry when you wake up.
Saliva helps protect the teeth, gums and soft tissues of the mouth. Persistent dryness may make speaking, chewing and swallowing uncomfortable while increasing the risk of cavities, mouth sores and oral infections.
Common causes of mouth breathing at night
Nasal congestion
When the nasal passages are blocked, the body may automatically switch to mouth breathing to maintain airflow. Temporary congestion can be caused by:
- A cold or respiratory infection
- Sinus inflammation
- Nasal swelling
- Environmental irritants
- Changes in temperature or humidity
Chronic congestion may also be associated with structural concerns such as a deviated septum or nasal polyps. Your doctor or an ear, nose and throat specialist can evaluate symptoms that do not improve.
Allergies
Allergic rhinitis occurs when the immune system reacts to substances such as pollen, dust mites, mould or pet dander. This reaction may cause nasal swelling, sneezing, itching and congestion, making it more difficult to breathe through the nose.
Allergic and nonallergic rhinitis can produce similar symptoms, but their triggers and treatments may differ. (AAAAI Education Center)
If allergies appear to be contributing to nighttime mouth breathing, consider tracking when symptoms occur and whether they worsen during certain seasons or after exposure to specific environments.
Sleep disorders
Mouth breathing may sometimes be associated with a sleep-related breathing disorder, including obstructive sleep apnea. Obstructive sleep apnea occurs when the upper airway repeatedly becomes blocked during sleep, causing breathing to stop and restart. (Mayo Clinic)
Other warning signs may include:
- Loud or persistent snoring
- Gasping or choking during sleep
- Pauses in breathing noticed by another person
- Morning headaches
- Waking with a dry mouth or sore throat
- Excessive daytime tiredness
- Difficulty concentrating
- Feeling unrefreshed after a full night of sleep
A sleep study may be recommended when sleep apnea is suspected. (NHLBI, NIH)
How to recognise nighttime mouth breathing
You may not realise you are breathing through your mouth while asleep. Clues can include:
- Frequently waking for water
- Dry or sticky mouth in the morning
- Cracked lips
- Sore or irritated throat
- Bad breath upon waking
- Drooling on your pillow
- Snoring
- Restless or interrupted sleep
- Difficulty tolerating CPAP therapy
Keeping a short sleep and symptom journal can help your doctor identify patterns.
Treatment approaches
The right approach depends on why mouth breathing is occurring. Treatment should focus on improving nasal airflow, addressing sleep-related concerns and managing dry mouth symptoms.
Address nasal congestion
Your doctor or pharmacist may recommend options such as saline rinses, humidification or treatment for sinus inflammation. Medication may be appropriate in some situations, but nasal sprays and decongestants should be used as directed. Overusing certain decongestant sprays can cause rebound congestion. (AAAAI)
Manage allergies
Reducing exposure to known allergens may help improve nasal breathing. Helpful steps may include:
- Washing bedding regularly
- Using allergen-resistant mattress and pillow covers
- Keeping pets out of the bedroom
- Managing indoor humidity
- Using a high-efficiency air filter
- Keeping windows closed during high-pollen periods
An allergist may recommend medication, nasal sprays, allergy testing or immunotherapy based on your symptoms.
Seek evaluation for sleep apnea
Speak with a health professional if mouth breathing occurs with loud snoring, gasping, breathing pauses or significant daytime sleepiness. Sleep apnea is a potentially serious condition and should not be self-diagnosed or treated with home remedies alone.
Treatment may include positive airway pressure therapy, an oral appliance, lifestyle changes or another approach based on the type and severity of the condition. (NHLBI, NIH)
Review CPAP mask fit and humidification
Some people using CPAP experience mouth dryness because of mask leakage, mouth breathing or inadequate humidification. A sleep specialist or equipment provider can assess the mask style, fit, pressure and humidifier settings.
Do not change your pressure settings or stop CPAP without talking to your sleep care team.
Manage dry mouth symptoms
Even while the underlying cause is being addressed, targeted dry mouth care may improve comfort. Consider:
- Drinking water regularly throughout the day
- Limiting tobacco, alcohol and excessive caffeine
- Using a bedside humidifier
- Maintaining regular dental appointments
- Using products specifically developed for dry mouth
Aquoral Protective Oral Spray creates a lipid-based protective coating inside the mouth to help relieve dry mouth symptoms. It is available without a prescription in Canada and can be part of your nighttime routine; ask your pharmacist or dentist if you have questions.
A note about mouth taping
Mouth taping is sometimes promoted online as a solution for nighttime mouth breathing. However, it does not treat the underlying cause and may be unsafe for people with nasal obstruction, respiratory conditions or undiagnosed sleep apnea. Speak with a qualified health professional before trying any method that restricts breathing during sleep.
When to speak with a health professional
Book an evaluation if mouth breathing and dry mouth occur regularly, interfere with sleep, or come with snoring, choking, breathing pauses or daytime exhaustion.
Finding the cause can lead to more effective treatment, better-quality sleep and improved oral comfort.
This article is general information and does not replace advice from your health professional. Content adapted for Canada; pending review.