Mouth vs Nose Breathing, ADHD and Sleep Issues

Studies point to meaningful differences in brain regulation between the two modes of breathing

The nose is the organ designed for breathing in the human body. This much is clear. A good deal of people are aware of this, and many even try to adhere to it on a regular basis. Yet, a surprising number are either oblivious or give its influence on their health scant attention. They proceed to routinely breathe unconsciously with the mouth, despite it being ill-suited for breathing whatsoever except in situations of high physical stress. In this article we will present some recent research indicating the meaningful impact of mouth breathing can have on deteriorating both sleep and day-time attention and impulsivity regulation.

Trends in ADHD Diagnoses and Sleep Issues

To begin with, let’s explore the rising trend in a couple of mental-health related topics, ADHD and sleep.

Attention Deficit Hyperactivity Disorder, otherwise known by the acronym ADHD, is affecting a growing percentage of the population in the 21st century. A study of 180,000 adolescents aged 4-17 in the United States over a 20 year period from 1997-2016 measured an almost doubling of diagnosed ADHD in the nationwide population. According to the study, 10% of the population were diagnosed with ADHD, up from 6%¹. And this does not factor in the many that were not diagnosed, yet experience attention and or impulsivity issues in their day-to-day lives.

What about the fundamental necessity of sleep? A study of over 30,000 individuals in the United States aged over 18 found an increase in prevalence of sleep insomnia or trouble sleeping from 17% to 19% from 2002-2012; and notably within the study, the growth in people aged 18-24 was far higher at 30%². These are high percentages, both on an absolute basis and in measuring the rise in trend.

Trends in mental health related issues

Let’s just zoom in a little into what we’re dealing with here when it comes to both sleep and ADHD:

• Sleep issues are self-explanatory, and though we can break down an array of unique reasons people encounter them, for the purpose of this article we will take a general approach defining sleep issues in the context of people who have trouble regularly sleeping a stable 7-8 hours per night.

• ADHD we can separate into a pair of its constituent parts:

  • Inability or a lack of willingness to pay attention for sustained periods

  • Proclivity for impulsive behaviour and an inability to regulate it, even having recognised the potentially harmful impact on well being and/or life.

Link Between ADHD and Sleep Issues

It may seem to some readers that it is common sense these two issues be related. If a person struggles to obtain a good nights sleep on a regular basis - which is imperative for both healing and re-invigorating the mind and body - they will tend to be low on energy, and low energy inherently makes it more challenging to pay attention and focus, as well as to regulate our behaviour. At the same time, if a person is frequently hyper-aroused this may often transfer unpredictably into the evenings and nights and affect the time they go to bed as well as the quality and length of sleep. It is somewhat like a vicious negative feedback loop. And the data backs up our common sense. Problems with sleep can lead to the development of ADHD-like symptoms, potentially resulting in misdiagnosis³⁴. Moreover, the effects of sleep troubles emerge as symptoms that are remarkably similar to those of ADHD⁵⁶

Another study involving neuroimaging analysis revealed that regions of the brain indicated a link between both ADHD and sleep disturbance. And while the study takes a uni-directional conclusion with its data suggesting a stronger relationship in the way of ADHD → sleep issues, for those looking to investigate this further from a neuroscience standpoint, it points out: “Lower gray matter volumes in the middle frontal gyrus and inferior frontal gyrus, amygdala, striatum, and insula were associated with both ADHD symptoms and sleep disturbances… Among the subcortical structures, we identified a number of genes with higher expression levels in those brain areas where a greater proportion of the brain-sleep association was mediated by ADHD. These genes included those playing key roles in dopamine signaling and in the circadian cycle.” ⁷

Mouth Breathing and Sleep

So, how is mouth or nose breathing related to all of this? Well, quite substantially as it turns out.

The strongest evidence for sleep issues giving rise to ADHD-like symptoms comes from a host of recent studies which investigated surgical intervention on breathing patterns during sleep (to allow for breathing to happen with the nose, instead of the mouth) and resulting in a significant improvement to the daytime behavioural patterns associated with ADHD⁸⁹. Furthermore, a systematic review in one of these studies indicated that the prevalence of a specific type of sleep issue - sleep apnea - in patients with ADHD (~30%) is far higher than in the general population (~3%)¹⁰.

In fact, the polarity in consequences from mouth breathing versus nose breathing during sleep has been noted in modern medical studies for over 500 years! The earliest account we can find of the “deleterious” effects from mouth breathing during sleep dates back to the 16th century made by the Dutch physician Levinus Lemnius.

To really understand what’s going on here, we have to investigate what’s happening in our brain and body when we breathe with our nose as well as when we breathe through the mouth. There are two ways to approach this: one is empirically by observing a sample of people who either nose or mouth breathe; and another is to understand the biological differences.

Understanding Nose and Mouth Breathing

There are a few significant differences in what happens biologically when we breathe through the nose in comparison to the mouth.

Perhaps the most pertinent of all is that the inherent design of the body intends for respiration to occur through the nose, the majority of the time. This has numerous ripple effects. One way is to analogise this with another component of our bodies - the necessity of using our feet to walk and our hands to perform more dextrous functions.

The Diaphragm

Natural breathing through the nose activates the use of the diaphragm muscle, which rests below the lungs and above the stomach. This muscle is designed primarily to assist with the breathing function in our bodies and its strength and pliability is necessary for the stability of the spine. It is not possible to maintain sustained use of the diaphragm by breathing with the mouth. When we breathe in through the nose and move the air into our belly, the diaphragm moves down laterally expanding the lower rib cage and creating greater lung volume capacity.

Facial Skeletal Development

When nasal breathing does not regularly occur during childhood, forcing primates to breathe through their mouths, the resulting change in breathing pattern can alter the natural growth of the craniofacial complex. This includes elongation of the face, narrowing of the dental arches, and increased facial height.

Nasal breathing promotes proper tongue posture, with the tongue resting against the palate, which encourages balanced growth of the facial structures. Research indicates that children who habitually breathe through their mouths may develop distinct facial characteristics, such as an increased mandibular plane angle, elongated lower anterior facial height, and reduced posterior facial height.¹¹

Nasal Passages

Inside the nose and sinuses there are tiny hairs called cilia. These cilia trap larger particles like dust, pollen, and pathogens before they enter the respiratory system. The nasal passages are also lined with a mucous membrane that traps smaller particles, including bacteria and viruses. The mucus contains antimicrobial substances like lysozyme, which can break down the cell walls of certain bacteria. Antibodies and nitric oxide (produced by the sinus mucosa) then act to destroy these microbes.

The nasal passages also humidify and warm incoming air, making it less likely to dry out the mucous membranes in the lower respiratory tract. The throat and lungs function more optimally with warm, moist air.

Nitric Oxide

Nitric oxide (NO) is essential for the proper functioning of the brain and the endothelial system (veins and arteries). Since this gas is produced in large quantities in the nasal sinuses, breathing through the mouth is like depriving yourself of the benefits of natural breathing, i.e. through the nose. Thanks to NO, nasal breathing improves the oxygenation of the brain, compared to breathing through the mouth.

The oxygen needed by the cells is supplied via the blood vessels by the red blood cells. The blood flow, and therefore the amount of oxygen, is dependent on two parameters: the pressure impelled by the heart and the diameter of the vessels. NO has a vasodilatory effect on these blood vessels (i.e. it increases their diameter) and therefore increases this blood flow. This dilation, especially in the lungs, allows oxygen to better penetrate the blood vessels and CO2 to escape. In 1998, Dr. Louis Ignarro was awarded the Nobel Prize in Medicine for his discoveries showing NO’s strong ability to improve cardiovascular health and prevent heart disease.

The Resonant Breath and ADHD

The autonomic nervous system has two components: a stress response and a recharge response. People with ADHD tend to have nervous systems which are out of sync, and most of the time the stress and recharge responses are under active. However, when the stress response kicks in for an individual with ADHD, it goes far and above the typical level. For the brain to work in its natural way - and to be less impulsive and hyperactive - both components of the nervous system need to work optimally and in the right balance.

At aware, we believe in the Resonant Breath as a way to bring ourselves into balance. Whether we are sitting at a desk at work, walking along the street, lying in bed, driving a car, we can practise this mode of breathing.

Several studies have looked at the effect of this type of conscious breathing on the nervous system, with strong results. One study found that slow breathing could improve sustained attention, affect, and cortisol levels.¹² Another study proposed that “slow deep breathing functionally resets the autonomic nervous system through stretch-induced inhibitory signals and hyperpolarization currents propagated through both neural and non-neural tissue which synchronises neural elements in the heart, lungs, limbic system and cortex.”¹³

Concluding Thoughts on Nose versus Mouth Breathing

Ok, now you might say the data highlighted in this article represents only isolated pockets of the world over a relatively short span of time. And you would be right in making this point. To this, we would respond by saying that the imperative principle of breathing with the nose, in lieu of the mouth, has been around dating back to the Upanishads in Ancient India some 2500 years ago.¹⁴ Modern science and modern principles (of before Christ and before Science) converge rather tightly to the same conclusion. This is not a “drop the mic” moment where we leave it at that, case solved, though. Rather, to simply serve as fuel for further investigation or experimental application, where necessary.

1. Twenty-Year Trends in Diagnosed Attention-Deficit/Hyperactivity Disorder Among US Children and Adolescents, 1997-2016. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6324288/

2. Ford ES, Cunningham TJ, Giles WH, Croft JB. Trends in insomnia and excessive daytime sleepiness among U.S. adults from 2002 to 2012. https://pubmed.ncbi.nlm.nih.gov/25747141/

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8. Soylu E, Soylu N, Yildirim YS, Sakallioglu O, Polat C, Orhan I. Psychiatric disorders and symptoms severity in patients with adenotonsillar hypertrophy before and after adenotonsillectomy. Int J Pediatr Otorhinolaryngol. 2013 https://pubmed.ncbi.nlm.nih.gov/24011939

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11. Zheng W, Zhang X, Dong J, He J. Facial morphological characteristics of mouth breathers vs. nasal breathers: A systematic review and meta‑analysis of lateral cephalometric data. Experimental and Therapeutic Medicine. 2020 https://doi.org/10.3892/etm.2020.8611

12. Ma X, Yue Z, Gong Z, Zhang H, Duan N, Chi Y, Wei G, Li Y. The Effect of Diaphragmatic Breathing on Attention, Negative Affect and Stress in Healthy Adults. Frontiers in Psychology. 2017 https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2017.00874/full

13. Jerath R, Edry J, Barnes V, Jerath V. Physiology of long pranayamic breathing: Neural respiratory elements may provide a mechanism that explains how slow deep breathing shifts the autonomic nervous system. Medical Hypotheses. 2006 https://www.sciencedirect.com/science/article/abs/pii/S0306987706001666?via%3Dihub

14. The Hindu Conception of the Functions of Breath.-A Study in Early Hindu Psycho-Physics, Arthur H. Ewing, Journal of the American Oriental Society, Vol. 22 (1901) https://www.jstor.org/stable/592433?seq=7