When we breathe we do not give it much thought, we just breathe without ever really thinking about it. Your body does it automatically, without much if any conscious effort.

Yet we should! It’s very important to pay close attention to how you or a loved one breathe. For most people, it’s healthier to breathe through your nose instead of your mouth. That’s because nose breathing is more natural and helps your body use the air you inhale more efficiently.

The first thing we do when we are born we take a breath. Babies can’t even breathe through their mouths until around three months of age. We continue breathing automatically without thinking about it for the rest of our lives. Unless there is an issue we continue breathing without much awareness. We do not necessarily always function at optimum mental and physical health when we mouth breathe. The problem with breathing is that it seems so easy and natural that we rarely give it a second thought.” Although breathing is a natural function, it can be negatively influenced by many factors such as mouth breathing, stress, sitting at a desk all day, eating processed foods, and excessive talking.

It is estimated that about 30 to 50 percent of adults breathe through their mouths, especially earlier in the day or at night. This could potentially lead to health issues like bad breath, dry mouth, bedwetting, and frequent urination at night.

Now that we have been wearing masks for over a year, mouth breathing is way more common than it used to be. We are doing it and don’t even realize it because it has become a habit. Even though we can breathe through our mouths we should not. When we breathe through our nose we get many benefits we do not get when we use our mouth.

Both the mouth and the nose are vital and very much underrated. To realize its importance just think about the last time you suffered from a bad cold. Nasal congestion and a runny nose have a noticeable effect on our ability to breathe, our energy levels, our ability to sleep, and our general ability to function. According to otolaryngologist Dr. Pat Barelli: “The role of the nose in health and in respiration has been greatly neglected by physicians.” 

The human nose was designed for breathing and smelling, whereas the mouth was designed for eating, chewing, drinking, speaking and smiling.

Since your nose was specifically designed to help you breathe, nasal breathing has many advantages.

These include:

  • humidify and warm inhaled air
  • increase airflow to arteries, veins, and nerves
  • increase nitric oxide, oxygen uptake, and circulation
  • slow down breathing
  • improve lung volume
  • help your diaphragm work properly
  • lower your risk of Asthma, allergies, and hay fever
  • reduce your risk of coughing
  • aid your immune system
  • lower your risk of snoring and sleep apnea
  • support the correct formation of teeth and mouth
  • Reduce cavity formation due to dry mouth
  • reduce exposure to foreign substances

Mouth breathing is common in individuals whose nasal passages are blocked or restricted. A deviated nasal septum or small nostril size, enlarged tonsils, or adenoids can lead a person to breathe through their mouth instead of their nose.

However, breathing through the mouth most of the time was not nature’s intention. Many studies have demonstrated that chronic mouth breathing can result in a number of adverse health consequences.

Possible adverse consequences of chronic mouth breathing may contribute to:

  •  Introduction of unfiltered, poorly humidified air into the lungs
  •  Upper-chest breathing (inefficient and tiring)
  •  Chronic over-breathing
  •  Greater incidence of snoring and sleep apnea
  •  Bad breath, dental decay, gum disease
  •  Dysfunction of the jaw joint (temporomandibular joint disorders)
  •  Narrowing of the dental arch, jaw and palate
  •  Crowded and crooked teeth
  •  Open bite, malocclusion (teeth not fitting together properly)
  •  Greater potential for relapse of orthodontic corrections
  •  Dysfunctions of the muscles around the jaw and lips
  •  Loss of lip tone with the lips becoming flaccid
  •  Noisy eating, speech and swallowing problems
  •  Trauma to soft tissues in the airways
  •  Enlarged tonsils and adenoids

Adapted from Graham T (2012)

Physiology of Breathing

Normal breathing is done through the nose. Each nostril functions independently and synergistically to filter, warm, moisturize, dehumidify and smell the air.

Babies are born nose breathers, but somewhere along the way nose breathing can change to mouth breathing, with dire consequences. The most obvious adverse effect of mouth breathing is dryness of the oral and pharyngeal tissues, leading to inflamed tonsils, tonsil stones, dry cough, swollen tongue, halitosis, gingivitis, and cavities.        

Normal respiration follows a gentle wave pattern with 10 to 12 breaths per minute. Mouth breathers take too many breaths, with rates from 12 to 20 breaths per minute or more. Breathing delivers oxygen to the cells of the body and removes excess carbon dioxide. Carbon dioxide is produced as a byproduct of exercise and the digestion of food. Carbon dioxide plays a significant role in the release of oxygen from hemoglobin. It also triggers breathing, maintains blood pH, and prevents smooth muscle spasms. All of these functions are reduced or impaired in mouth breathers.

Surprisingly, oxygen is absorbed on the exhale, not on the inhale. The backpressure created in the lungs with the slower exhale of nose breathing allows more time for the lungs to transfer oxygen to the blood. This exchange requires carbon dioxide. Exhaling through the mouth blows the carbon dioxide out too quickly, resulting in less oxygen being absorbed. The reason nasal breathing results in more oxygen being absorbed is nitric oxide is released in the nasal cavity and inhaled with nose breathing. Nitric oxide increases the efficiency of oxygen exchange by 18 percent. There is no nitric oxide inhaled with mouth breathing, therefore less oxygen is absorbed. The reduced oxygen absorption leads to a cascade of sleep, stamina, energy level, and ADHD problems. Children diagnosed with ADHD may in fact be mouth breathers who are simply sleep-deprived. 

With nasal breathing, the tongue rests against the palate without touching the teeth. In this position, the tongue provides passive pressure that stimulates stem cells located in the palatal suture and within the periodontal ligaments around all the teeth, to direct normal palatal growth. The teeth erupt around the tongue, producing a healthy arch form. The lateral pressures from the tongue counter inward forces from the buccinator muscles  

Several things go wrong with mouth breathing. The low carbon dioxide levels associated with mouth breathing lead to over-breathing or hyperventilation. With less oxygen being delivered to the brain, muscles, and all the cells of the body, the body functions less than optimally. Sleep is often disturbed and of poor quality, leaving the mouth breather tired in the morning and feeling fatigued mid-afternoon. As the mouth dries out, the pH of saliva drops, leading to increased caries. This dryness and lack of air filtration in mouth breathing cause enlarged and inflamed tonsils and adenoids and an increased risk of upper respiratory tract infections. Lower levels of carbon dioxide cause smooth muscle spasms associated with gastric reflux, asthma, and bedwetting. Smooth muscle is found throughout the body – in the respiratory system, digestive system, and circulatory system.   

With mouth breathing, the tongue is down and forward allowing the buccinator muscles to push unopposed, causing the upper arch to collapse. Children who mouth breathe have an underdeveloped, narrow maxilla with a high vaulted palate. They develop a retrognathic mandible and generally have a long face. This is known as long face syndrome.

Some think the long face syndrome associated with mouth breathing is actually dictated by genetics rather than breathing. To see if mouth breathing alone could change jaw development and occlusion, Dr. Egil Harvold and his team tested this idea in monkeys. They artificially switched nose-breathing monkeys to mouth-breathing by surgically blocking their noses with silicone plugs. The monkeys were uncomfortable with the new mouth breathing but eventually adapted, and all developed changes to their jaws and malocclusion. 

Mouth breathing-related problems of skeletal development will set children up for obstructive sleep apnea later in life. In addition to changes in the development of both maxilla and mandible, the airway is constricted, predisposing the child’s sleep problems.     

It may seem logical that mouth breathing occurs because the nose is congested, but that is not always the case. The brain of a mouth breather thinks carbon dioxide is being lost too quickly from the nose and stimulates the goblet cells to produce mucus in the nose to slow breathing. This creates a vicious circle of mouth breathing triggering mucous formation, nasal passage blocking, leading to more mouth breathing. So in fact, mouth breathing can cause nasal congestion leading to more mouth breathing.    

Recognizing mouth breathing

Determining if someone is a mouth breather is not always easy. Some people admit they always breathe through their mouths. Others believe they are nose breathers, but if you watch them, their mouth is open most of the time. Sitting still, they may have their mouth closed, but if they get up and walk across the room, their mouth is open. Chewing with the mouth open may be done so the person can breathe while eating. One sign of mouth breathing is an addiction to Chapstick or lip gloss. An open mouth leads to drooling, both awake and asleep, causing chapped lips and a tendency for mouth breathers to lick their lips frequently. A closed-mouth lip seal is efficient at keeping saliva in and air out, but chronic mouth breathers may find it very difficult to hold their lips together. 

Mouth breathing at night dries the tissues so the mouth, teeth, tissue, and throat are all dry upon waking. Always having a glass or bottle of water at hand might signal systemic xerostomia, but it is also a sign of mouth breathing. If someone wakes with a dry mouth, they are likely a mouth breather at night, which means they are also likely mouth breathing during the day.

Dental hygienists are in the perfect position to recognize mouth breathing. Before asking patients to “open wide,” check first for mouth breathing.  

(Click this link to read more articles by Trisha O’Hehir.)