Mouth breathing at night is common, but if it happens regularly it may be a sign that air is not moving freely through the nose. Many people only notice the problem when they wake with a dry mouth, sore throat, bad breath, disturbed sleep or a blocked nose in the morning.
Occasional mouth breathing can happen during a cold, hay fever flare-up or sinus infection. However, regular mouth breathing at night can sometimes point to an underlying nasal or throat problem that may need proper assessment.
The nose is designed to warm, filter and humidify the air we breathe. When nasal airflow is reduced, the mouth often opens during sleep to compensate. This can affect sleep quality and may also be linked with snoring.
Why do I breathe through my mouth at night?
There are several reasons why someone may breathe through their mouth while sleeping. The most common reason is nasal obstruction, which simply means reduced airflow through one or both sides of the nose.
A blocked nose may be caused by swelling inside the nose, allergy, infection, a deviated septum, nasal polyps, enlarged turbinates or weakness of the nasal side wall. London ENT has more information on common causes of a blocked nose and how these problems may be investigated.
In some people, mouth breathing becomes more noticeable when lying down. This can happen because nasal tissues may swell slightly at night, making airflow feel more restricted.
Mouth breathing and snoring
Mouth breathing and snoring are closely linked. When the nose is blocked, the mouth naturally opens during sleep. This can increase vibration in the throat, soft palate and surrounding tissues, which may make snoring more likely.
Snoring is not always serious, but it can be disruptive and may sometimes be linked with obstructive sleep apnoea, especially if there are pauses in breathing, choking episodes, excessive daytime tiredness or restless sleep.
London ENT explains more about the connection between nasal blockage, throat vibration and snoring.
Could a blocked nose be the cause?
A blocked nose is one of the most common reasons for mouth breathing at night. Some people feel blocked on both sides, while others mainly notice one nostril.
If one side always feels restricted, a structural issue such as a deviated septum may be involved. The septum is the wall of cartilage and bone that separates the two sides of the nose. If it is bent or deviated, it can narrow the airway and make nasal breathing more difficult.
London ENT has a useful article on why one nostril always feels blocked, which explains some of the possible reasons for one-sided nasal obstruction.
Allergies and night-time mouth breathing
Allergies can also contribute to mouth breathing at night. Allergic rhinitis can cause swelling of the nasal lining, sneezing, itching, mucus and congestion. If the nose becomes blocked, breathing through the mouth during sleep may become more likely.
This can be seasonal, such as hay fever, or it can happen all year round if the trigger is dust mites, pets, mould or other indoor allergens.
If allergy is the cause, treatment may involve avoiding triggers where possible, nasal sprays, antihistamines or other medication. However, if symptoms are persistent or one-sided, it is important not to assume it is only allergy.
Deviated septum and nasal structure
A deviated septum can make nasal breathing more difficult, particularly at night. Some people are born with a deviated septum, while others develop it after an injury or trauma to the nose.
If the blockage is significant, septoplasty may be considered. Septoplasty is surgery to straighten the septum and improve airflow through the nose. This is different from cosmetic rhinoplasty, although in some cases nose reshaping and septal correction may be combined.
You can read more about septoplasty in London and Essex and when it may be used to help nasal breathing.
Could nasal valve collapse be involved?
Nasal valve collapse is another possible cause of poor nasal airflow. The nasal valve is a narrow area inside the nose that plays an important role in breathing. If this area is weak or narrowed, it can restrict airflow and make the nose feel blocked.
Some people notice that breathing improves if they gently pull the side of the nose outwards. This does not confirm the diagnosis on its own, but it can be a clue that the nasal valve area may need assessment.
London ENT provides information on nasal valve surgery for patients where weakness or narrowing of the nasal valve is affecting breathing.
Mouth breathing in children
Mouth breathing at night can also affect children. In younger patients, enlarged adenoids may be a cause of blocked nose, snoring and mouth breathing. Adenoids sit at the back of the nose and can become enlarged during childhood.
If a child regularly sleeps with their mouth open, snores heavily, has disturbed sleep, or appears tired during the day, it may be worth seeking medical advice.
London ENT has more information on adenoidectomy and when enlarged adenoids may need treatment.
When should you see an ENT specialist?
You should consider seeing an ENT specialist if mouth breathing at night is persistent, worsening or linked with other symptoms.
It may be worth arranging an assessment if you have:
- Persistent blocked nose
- One nostril that always feels blocked
- Loud snoring
- Pauses in breathing during sleep
- Waking with a dry mouth or sore throat
- Poor sleep quality
- Daytime tiredness
- Reduced sense of smell
- Repeated sinus symptoms
- A history of nasal injury
- Concern about a deviated septum or nasal obstruction
An ENT assessment can help identify whether the problem is caused by allergy, inflammation, nasal structure, sinus disease, polyps, adenoids or another issue.
How is night-time mouth breathing assessed?
Assessment usually starts with a discussion about your symptoms, how long they have been present and whether they are worse at certain times of year or in certain environments.
The nose and throat may be examined, and in some cases nasal endoscopy may be recommended. This allows the specialist to look inside the nasal passages in more detail.
Further tests may be suggested if there are signs of sinus disease, allergy or sleep-related breathing problems.
London ENT provides information about common nose symptoms and wider ENT symptoms that may help patients understand when to seek advice.
Can treatment help?
Treatment depends on the cause. If the problem is allergy-related, medical treatment may help reduce swelling and improve airflow. If the issue is structural, such as a deviated septum or nasal valve collapse, surgery may sometimes be considered.
For patients with both nasal blockage and concerns about the shape of the nose, a combined approach may be appropriate. London ENT provides information about nose surgery in Essex for patients considering functional or cosmetic nasal surgery.
The most important step is to understand why mouth breathing is happening. Once the cause is clear, treatment can be tailored properly.
Mouth breathing at night should not be ignored
Mouth breathing at night is not always serious, but it can be a sign that the nose is not working as well as it should. If it happens regularly, especially alongside snoring, blocked nose, poor sleep or daytime tiredness, it is worth looking into the cause.
A proper ENT assessment can help identify whether the issue is temporary, allergy-related, structural or linked with a wider sleep breathing problem.
If you are concerned about mouth breathing at night, nasal obstruction or snoring, London ENT can provide consultant-led assessment and advice across London and Essex.