The human body was designed for nasal breathing.
When dysfunctional breathing is present, several compounding consequences exist throughout the body.
To truly understand the systemic impacts of mouth breathing, it's important to acknowledge the benefits of nasal breathing and recognize the conflicting effects mouth breathing brings about [8].
Nasal Breathing
Proper tongue posture
Activates the parasympathetic nervous system
Slows breathing
Creates deeper breathing
Activates the diaphragm and vagus nerve
Increases oxygen uptake and circulation
Increases nitric oxide concentrations
Filters foreign particles like dust, allergens, viruses, and bacteria
Warms and moistens inhaled air
Encourages optimal jaw and facial development
Encourages adequate saliva production
Promotes fresh breath
Helps prevent snoring and sleep apnea
Increases stamina and endurance
Supports brain development in children
Mouth Breathing
Low tongue posture
Activates the sympathetic nervous system
Often fast, hard, and audible
Involves visible movement of the upper chest
Shallow breathing leads to hyperventilation
Reduces levels of carbon dioxide in circulation, which changes the acidity of the blood and contributes to painful myofascial trigger points and muscles
Encourages elongated, narrow facial and recessed chin development
Dries saliva, which increases oral bacteria
Promotes bad breath (halitosis)
Increases cavity rate
Notably, numerous research studies have shown that mouth breathing as a child leads to changes in muscle recruitment in the upper airway, which alters facial and jaw growth and development. If the changes are severe enough, they may require surgical intervention later in life to widen the jaws, open the airway, and give the tongue and teeth the space they should have had.
Research has concluded that mouth-breathing children have cervical spine postural changes and decreased respiratory muscle strength compared with nasal-breathing children. [8]
Additionally, nasal breathing and mouth breathing are known to activate opposing centers within the nervous system known as the parasympathetic nervous system and the sympathetic nervous system, respectively. See below for more on this!
As discussed in my previous blog post, there are multiple signs and symptoms of mouth breathing - and thus narrow jaw development - and early intervention is key for life-long health and wellness.
[9]
By age 6, nearly 60% of the adult face has developed. [8]
Now knowing the detrimental impacts mouth breathing has, let's discuss some of the top causes of chronic mouth breathing.
Nasal obstruction
Enlarged tonsils and/or adenoids
Chronic nasal congestion
Allergies
Deviated septum
Nasal polyps
Enlarged nasal turbinates
Low tongue posture
Tongue tie and/or lip tie
Nasal valve collapse
Genetic factors
Unhealthy oral habits
Personally, as a myofunctional therapist, the top four reasons for mouth breathing I see in my patients include chronic nasal congestion, unhealthy oral habits, low tongue posture, and enlarged tonsils and/or adenoids. However, as you can see, there are several factors that can lead to mouth breathing, so working with trained airway providers to determine where the root cause of dysfunctional breathing comes from is critical for the long-term success of any interventions.
Systemic Changes
Two of the largest system-wide impacts of mouth breathing include changes in blood chemistry and improper activation of the nervous system.
1. Blood Chemistry
Nitric oxide (NO) is essential to proper cellular functions of the human body, so what is it? And how does it change with unhealthy breathing habits?
[4]
NO is a gas formed by combining nitrogen and oxygen [5]. Within the body, the main site of production of NO is the paranasal sinuses [6]; It is excreted from the paranasal sinuses continuously into the nasal airways where it reaches the lungs during inspiration, especially with nasal breathing [7]. Overall, NO acts as an important chemical messenger involved in many body functions [5].
[3]
Vasodilation - decreases blood pressure and improves blood flow to organs
Anti-inflammatory action in arteries
Prevents blood clots and obstructions in arteries
Immune defense - destruction of viruses and parasitic organisms
Plays a role in respiration
Enhances memory and learning
Protects skin from harmful ionizing radiation
Promotes a healthy digestive tract - regulates the secretion of digestive hormones and enzymes
Hormones - influences the secretion of hormones from several glands
Regulates bladder function
Signaling molecule - maintains normal body functions
Blood oxygenation - regulates the binding and release of oxygen within hemoglobin
Low nitric oxide levels are linked to high blood pressure, heart disease, heart attacks, strokes, digestive tract issues such as IBS, Alzheimer's disease, dementia, and bladder issues. [3]
With nasal breathing, nitric oxide (NO) is released, which is needed to increase carbon dioxide in the blood, which in turn is what releases oxygen. [2]
With mouth breathing, nitric oxide (NO) is not effectively released, which means cells are not getting as much oxygen, which often leads to fatigue and oxidative stress. [2]
Overall, mouth breathing leads to decreased levels of NO release from the paranasal sinuses, chronic hyperventilation or overbreathing, reduced blood circulation, lower carbon dioxide levels, and vasoconstriction of airways. [3]
2. Vagus Nerve Stimulation
A second important systemic function that is impacted by mouth breathing is stimulation of the tenth cranial nerve - the vagus nerve.
The vagus nerve is the longest, most complex cranial nerve. It is involved in the functions of the autonomic nervous system, which is responsible for involuntary physiological processes such as heart rate, digestion, and pupil dilation. [1]
The autonomic nervous system has two parts [1]
Parasympathetic nervous system - the 'rest and digest' or relaxation mode
Sympathetic nervous system - the 'fight or flight' or stress mode
[1]
As mentioned above, nasal breathing activates diaphragmatic breathing, and any movement of the diaphragm stimulates the vagus nerve, which in turn stimulates the parasympathetic nervous system and helps the body relax.
Additionally, end branches of the vagus nerve innervate the palate and are stimulated with nasal breathing, proper tongue posture, and correct swallowing patterns.
Conversely, mouth breathing is typically an upper chest motion, which means the diaphragm isn't moving and thus vagus nerve stimulation is bypassed leading to activation of the sympathetic nervous system. This leads to living in a state of chronic fight-or-flight, which has a direct impact on digestion and often develops into mental health struggles such as anxiety and depression.
"The vagus nerve is one of the primary parasympathetic cranial nerves and drives the digestive system. Correct swallowing activates rest and digest messages that must begin in the mouth."
- Dr. Steven Lin
By stimulating the vagus nerve, one can facilitate a physiological relaxation response in the body, which helps to calm the body down by activating the parasympathetic nervous system. [1]
Treatment Options
If mouth breathing is something you struggle with, there are several treatment options available.
Currently, two of the top forms of intervention for mouth breathing include the removal of tonsils and/or adenoids and the use of palatal expansion via surgical or non-surgical orthodontic treatment.
In a study on the impact of rapid palatal expansion (RPE) on adenoid and tonsil sizes in children, 90.0% of patients who underwent RPE had significantly reduced adenoids and 97.5% had a reduction in tonsil size. [10]
Because the removal of tonsils and/or adenoids is an invasive surgery and has a chance of tissue regrowth after removal, it is a last-case intervention for many providers. Instead, if patients receive early intervention orthodontic treatment that widens their arches while they're still growing and creates the space needed for the tongue and all teeth to fit, less invasive treatment options are possible later in life.
Again, early intervention is key.
All children should have an evaluation by an airway trained orthodontist by age 7 at the latest!
An ever-growing list of treatment options for mouth breathing in both children and adults includes the following:
Orofacial myofunctional therapy - addresses muscle dysfunction and harmful habits
Orthodontic treatment (i.e. braces) - helps to create more tongue space, which ultimately leads to increased airway space
Surgically assisted palatal expansion - a form of surgical intervention used to create wider dental arches in adults after growth has been completed
Tonsil and adenoid removal - a last-resort option for children and adults who have chronic enlarged tonsils caused by allergies, systemic inflammation, and more
Nasal dilators and mouth tape - short-term quick fixes that aid in keeping the nose open and the mouth closed during sleep
It's important to understand that narrow dental arches and enlarged tonsils/adenoids are a symptom of something deeper just as nasal dilators and mouth tape are more of a bandaid treatment option that don't treat the true root cause of dysfunction.
While pursuing several avenues for comprehensive treatment is often critical for the best long-term results, it's imperative to find the true underlying dysfunction(s) that are creating lifelong oral and systemic impacts.
Talk soon,
Liz Laney, Myofunctional Therapist
*None of the information included in this post is intended to be medical advice. Please talk with your healthcare provider(s) before making lifestyle changes or starting/stopping any medications and/or diets.
Resources
1. Cai J. The Vagus Nerve & Diaphragm. Kai Health. 6AD. https://www.kaihealth.com.au/blog/the-vagus-nerve-amp-diaphragm.
2. Galante AP. Benefits of breathing through your nose. Warren NJ Sleep Specialist. https://www.drgalante.com/sleep-apnea/benefits-breathing-through-nose/.
3. Heidi Dickerson, DDS, LVIM, FIAPA. Nitric Oxide & Mouth Breathing: Physiology you Want to Understand.
4. HospiMedica International staff writers. Portable nasal spray that destroys SARS-COV-2 could prove to be breakthrough covid-19 treatment. Hospimedica.com. April 12, 2021. https://www.hospimedica.com/covid-19/articles/294787821/portable-nasal-spray-that-destroys-sars-cov-2-could-prove-to-be-breakthrough-covid-19-treatment.html.
5. Hudgens S. What is nitric oxide? Health. July 23, 2023. https://www.health.com/nitric-oxide-7557367#:~:text=However%2C%20nitric%20oxide%20is%20a,damage%20when%20taken%20in%20excess.
6. Lundberg JO, Farkas-Szallasi T, Weitzberg E, Rinder J, Lidholm J, Anggåard A, Hökfelt T, Lundberg JM, Alving K. High nitric oxide production in human paranasal sinuses. Nat Med. 1995 Apr;1(4):370-3. doi: 10.1038/nm0495-370. PMID: 7585069.
7. Lundberg JO, Settergren G, Gelinder S, Lundberg JM, Alving K, Weitzberg E. Inhalation of nasally derived nitric oxide modulates pulmonary function in humans. Acta Physiol Scand. 1996 Dec;158(4):343-7. doi: 10.1046/j.1365-201X.1996.557321000.x. PMID: 8971255.
8. McKeown P. Mouth breathing face: How to fix and sleep effects. Oxygen Advantage. Accessed August 6, 2023. https://oxygenadvantage.com/science/mouth-breathing/.
9. White TD, Black MT, Folkens PA. Chapter 4 - Skull: Cranium and Mandible. Human Osteology (Third Edition). Published online 2012:43-100. doi:10.1016/b978-0-12-374134-9.50004-0
10. Yoon A, Abdelwahab M, Bockow R, et al. Impact of rapid palatal expansion on the size of adenoids and tonsils in children. Sleep Med. 2022;92:96-102. doi:10.1016/j.sleep.2022.02.011
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