How Mouth Breathing Intensifies Sleep Apnea Symptoms

Breathing predominantly through the mouth while sleeping is quite common but is not ideal. This type of nocturnal breathing can cause a dry mouth in the morning, bad breath and is also why some people experience drooling while asleep. 

In rare cases, a mouth breather can also undergo a slight change in facial appearance. Others experience sleep apnea, which lowers the quality of sleep -- leading to daytime drowsiness and serious medical conditions like heart disease.

Mouth breathing while sleeping is often an ingrained habit from childhood -- and changing the habit is difficult in later life. However, there are a number of physical or medical conditions that can also influence the onset of the habit. These can include:

  • Deviated septum
  • Enlarged adenoids
  • Enlarged tonsils
  • Sinusitis

In many cases the problem may be a temporary one that can be attributed to a head cold, an allergy or just a blocked nose. In such cases an over-the-counter medication may resolve the issue. But for a sleep apnea mouth breather the solution may not be so simple and surgery may be required.

Differences Between Nose and Mouth Breathing

Mouth breathing often starts at an early age with some experts estimating that 10% to 25% of children are mouth breathers. Although not a major issue in childhood it can become a problem in later life and breathing through the nose is infinitely preferable for a couple of reasons:

Small nasal hairs (cilia) filter out harmful allergens, microscopic debris and even minuscule insects.

The nose houses small bony structures (turbinates) that moisten the inhaled air which helps with throat and lung function.

Breathing through the nose allows the air to warm gradually and the lungs and throat prefer warmer air which is easier for bodily tissue to absorb.

Link to Sleep Apnea

Although it is by no means a certainty, research has shown that mouth breathers are more prone to sleep apnea and obstructive sleep apnea. The precise reason for this is still unknown but a recent scientific experiment may shine some light on the matter.

The subject in the experiment allowed researchers at Stanford University to block his nostrils while sleeping over a period of ten days. The effects were almost instantaneous as the subject's blood pressure jumped by 13 points bringing him into an early stage of hypertension. The heart rate became somewhat erratic indicating stress while the pulse rate also increased. During the day, there was also a reported loss of concentration and some mental confusion.

Most significantly, perhaps, was the fact that the subject (not previously a snorer) began snoring for hours at a time and was afterwards diagnosed with obstructive sleep apnea. While the test and results were extremely interesting, it does not mean that every mouth breather is destined to suffer from obstructive sleep apnea.

Cause and Cure

The factors that lead to mouth breathing are many and will vary from person to person. For many children it is just a habit they have fallen into -- but this does not mean there are no medical reasons for the problem. 

Every case must be assessed individually by a doctor or sleep specialist who may run a series of tests to pinpoint the exact cause.

A person may be totally unaware that he or she is a mouth breather but there are some signs that this may be the case to look out for:

  • Snoring
  • Dry mouth
  • Bad breath
  • Hoarseness or a sore throat

Because breathing through the mouth adversely impacts on the quality of sleep, it is also quite common for a mouth breather to feel unusually tired, listless and even irritable the morning after what was (supposedly) a good night's sleep. 

If any, some or all of these symptoms persist, it is advisable to consult a doctor who can investigate the cause of the problem and advise on a corrective course of action.

If the root cause of the problem is a medical condition, such as a deviated septum, sinusitis, enlarged adenoids or tonsils, minor surgery may be necessary. But it is more likely the problems are due to minor, temporary ailments like a cold, flu, allergies or a reaction to medicine.


Whether a person is a mouth-breather will be determined by a series of questions and answers and some visual and breathing tests. The questions are designed to get an overview of a patient's habits and symptoms, while the tests should provide valuable clues as to what lies at the heart of the problem and how best to address the possible causes.

The visual and breathing tests cover:

Visual. The doctor will look for visual clues that may be contributing factors to nocturnal mouth breathing. These include the quality of how lips seal, changes in posture, dark circles under the eyes, an elongated face, open bite, narrow or high palate, gum inflammations, early gingivitis (gum disease).

Breathing. There are three tests that can be carried out to check for any breathing irregularities. These are:

  • Graded mirror test which is used to look for condensation indicative of breathing through the nose.
  • Lip seal test evaluates the effectiveness of the seal between the lips and how easy or difficult it is for the patient to breathe through the nose with the mouth fully closed.
  • Water retention test is designed to detect a patient's ability to retain water in the mouth without any leakage.

These tests can help confirm whether mouth breathing at night is an issue but cannot determine whether the issue will lead to obstructive sleep apnea or not. Seeking treatment at this stage is preferable to letting the situation continue and risking more serious sleeping issues in the future.

Change of Habit

Breathing through the nose is far better for overall health and more conducive to a good night's rest for everybody and this is even more true for a sleep apnea mouth breather. 

Although positive airway pressure (PAP) therapy is very effective in relieving the disorders associated with obstructive sleep apnea these types of devices are even more effective for people who regularly breathe through the nose.

Switching from mouth breathing to nose breathing is not an easy undertaking but, with the right guidance from a qualified professional, it can be done.