The Breathing Expert: Mouth Breathing Is Destroying Your Health

In this podcast episode, James Nestor, renowned author and expert on breathing, explores the critical role that proper breathing plays in health, athletic performance, and chronic disease management. Drawing on extensive research and personal experience, he reveals why most people breathe dysfunctionally, the consequences of mouth breathing, the intersection between modern lifestyle and respiratory health, and practical ways to retrain oneself for better breathing. The conversation delves into topics such as nasal breathing benefits, the physiology of oxygen and carbon dioxide balance, the link between disrupted breathing and conditions like asthma, sleep apnea, ADHD, and anxiety, as well as breathwork techniques and their impact on longevity and peak physical performance.

Dysfunctional Breathing and Modern Health

James begins by highlighting a widespread issue: most people breathe incorrectly, often through their mouths, which is a dysfunctional default pattern. Despite breathing being an unconscious and constant activity, the majority of modern humans experience compromised respiratory health manifested as asthma, anxiety, snoring, COPD, and other ailments. This epidemic largely stems from industrialization's impact on human physiology and lifestyle, especially in Western countries, leading to structural changes in the face and airways that impair effective breathing.

Structural Causes: Jaw Development and Malocclusion

Central to dysfunctional breathing is a structural problem—the modern human mouth is too small. By examining ancient skulls dating back hundreds of years, Nestor points out that predecessors had wide mouths and straight teeth, while about 90% of today's population suffers from malocclusion, a condition where teeth grow crooked due to lack of space. Historically, orthodontics often opted for tooth extractions to address crowding, but this approach may exacerbate airway constriction by narrowing the mouth and pushing the palate upward, limiting nasal airflow. This "craning back" of the mouth is akin to foot binding, restricting facial development and promoting mouth breathing as an easier way to get air.

The Role of Diet and Chewing in Jaw Development

Nestor connects these anatomical changes to the shift toward softer, industrialized foods over the last centuries. Our ancestors engaged in prolonged chewing—up to two or three hours daily—on tough foods, which developed stronger jaw musculature and wider palates, adequate to accommodate teeth properly. Conversely, modern processed foods require minimal chewing, especially in early childhood during critical growth periods, which leads to underdeveloped jaws and narrower airways. This dietary shift strongly correlates with increases in mouth breathing and airway disorders globally, regardless of culture or geography.

Mouth Breathing vs. Nasal Breathing

Mouth breathing is not the normal or beneficial way to breathe; it is intended as a backup system when nasal breathing is obstructed. Nasal breathing plays a vital role in filtering, humidifying, and warming inhaled air, as well as producing nitric oxide, a molecule vital for killing pathogens and improving oxygen absorption. Mouth breathing leads to short, shallow breaths predominantly into the chest, which diminishes oxygen uptake efficiency and causes hyperventilation. This improper respiratory pattern disrupts carbon dioxide balance, acid-base homeostasis, and activates the sympathetic nervous system, placing the body in a chronic stress state, exacerbating anxiety and other health issues.

Oxygen and Carbon Dioxide Physiology

Contrary to common belief, carbon dioxide is not merely a waste product but an essential participant in oxygen delivery to tissues. Oxygen binds to hemoglobin in red blood cells, but carbon dioxide is necessary for oxygen to detach and be utilized at the cellular level. Overbreathing causes excessive loss of CO2, leading to vasoconstriction and decreased oxygen delivery despite adequate blood oxygen saturation levels. This imbalance underpins many chronic health problems by impairing cellular metabolism and maintaining heightened sympathetic nervous activity.

Sedentary Lifestyle and Poor Posture Impact

Nestor underscores the influence of contemporary sedentary lifestyles on breathing quality. Constantly hunched postures and weak core muscles limit diaphragm movement and lung expansion. Poor posture reduces the depth and effectiveness of breaths, decreasing lung capacity over time. Even nasal breathing is compromised if posture is poor, further contributing to health deterioration.

Indoor Air Quality and Carbon Dioxide Exposure

Beyond individual breathing habits, environmental factors such as indoor air quality also impact respiratory health. Nestor and his research team measured CO2 levels in various indoor environments like schools, offices, hotels, and airplanes, finding frequently elevated concentrations, often exceeding 1,500 parts per million (ppm), a threshold correlated with cognitive decline, anxiety, and reduced performance. Well-ventilated spaces with CO2 near outdoor levels (~400 ppm) are rare, making many shared environments detrimental to health and alertness, especially for children and workers.

Mouth Breathing and Its Connection to Chronic Diseases

There is strong evidence linking mouth breathing and dysfunctional respiratory patterns with chronic illnesses such as asthma, sleep apnea, hypertension, and type 2 diabetes. Asthma often arises after prolonged nasal congestion leads to chronic mouth breathing, which compromises airway function and immune defense. Studies reveal that many people with asthma experience symptom relief or remission when retraining their breathing to nasal patterns and slower rates. Similarly, sleep apnea, connected to structural airway restrictions and poor breathing habits, disrupts restorative sleep and increases risks for cardiovascular disease and diabetes.

Sleep Apnea and Sleep-Disordered Breathing

Sleep apnea is prevalent, affecting up to 20% of adults, and is a major contributor to chronic disease. Mouth breathing at night often leads to snoring and obstructive events, fragmenting sleep and triggering systemic stress responses. While standard treatments like CPAP are effective, adherence is low. Nestor emphasizes that addressing root causes—improving nasal airflow, airway structure, and breathing habits—is essential. Simple interventions like sleep tape to encourage nasal breathing, nasal strips to widen nostrils, and posture correction can substantially improve sleep quality in many cases. However, these strategies are not universal solutions; structural abnormalities require medical intervention.

The Stanford Mouth Breathing Experiment

To quantify the effects of mouth vs. nasal breathing, Nestor participated in a 20-day controlled experiment. For ten days, subjects forced mouth breathing, then switched to nasal breathing for the next ten days, with diet and activities controlled. Results were dramatic: snoring increased by 1300%, sleep apnea developed within days, blood pressure rose to stage one hypertension levels, stress hormones spiked, heart rate variability dropped, and cognitive function deteriorated. Conversely, nasal breathing restored normalcy within 48 hours, underscoring breathing's profound impact on physiological health.

Relationship Between ADHD and Sleep-Disordered Breathing

One of the more surprising revelations discussed is the connection between sleep-disordered breathing and childhood ADHD. Research shows that 70-80% of children with ADHD suffer from sleep-disordered breathing, including enlarged tonsils and adenoids that force mouth breathing. Surgical removal of these tissues often alleviates ADHD symptoms, suggesting that many behavioral issues may be rooted in poor sleep quality due to compromised breathing. While not claiming sleep breathing causes all ADHD, Nestor stresses that airway health should be among the first considerations in diagnosis and treatment.

Anxiety, Panic, and Breathing Patterns

Anxiety and panic disorders share a physiological basis with dysfunctional breathing. Individuals with anxiety tend to have low CO2 tolerance stemming from chronic overbreathing, which triggers hyperventilation and sympathetic overactivation. Techniques that help increase CO2 tolerance—such as slow nasal breathing, controlled breath holds, or breathing into cupped hands—can reduce the incidence and severity of panic attacks. This reframes anxiety management as a skill in respiratory regulation as much as psychological intervention.

Breath Training and Breathwork Practices

Nestor explains that while breathwork modalities like Wim Hof Method and holotropic breathing produce powerful experiences through intentional stress induction and CO2 manipulation, they are ultimately supplementary to establishing baseline healthy breathing habits. Without a foundation of normal, nasal, diaphragmatic breathing, these advanced techniques offer limited long-term benefit and may even cause harm. Training should begin with becoming an obligate nasal breather during rest and progressively build CO2 tolerance and lung capacity.

Daily Breathing Training and Practical Tips

To adopt healthier breathing patterns, Nestor recommends simple protocols. These include setting frequent reminders to check breathing posture and mode, using a piece of tape to gently encourage nasal breathing at rest and during sleep, and practicing diaphragmatic (belly) breathing to ensure the lungs fully inflate. Breath-holding tests such as the BOLT (Body Oxygen Level Test) help track CO2 tolerance improvements. Nasal strips can assist those with partial nasal obstruction, while children benefit greatly from early dental assessments specialized in airway health to prevent future malocclusion.

Breath and Athletic Performance

In sports, breathing efficiency directly translates to enhanced endurance, recovery, and performance. Trainers increasingly focus on breath training to improve CO2 tolerance, lung capacity, and oxygen utilization. Nasal breathing, even during exercise, conserves energy by reducing unnecessary respiratory effort. While it can be challenging at first—especially during higher-intensity activities—building this capacity over time leads to significant gains. For some sports like swimming, optimal breathing mechanics differ, but overall breath control remains paramount.

The Intersection of Breath, Longevity, and Healthspan

Lung function is one of the most accurate predictors of lifespan, surpassing many other markers including cardiovascular measures. Maintaining lung capacity through improved breathing techniques slows the decline associated with aging. Proper breathing reduces systemic inflammation, improves oxygen delivery, and supports organ health. Practicing deep, slow nasal breathing combined with physical activity can substantially extend healthspan.

Air Quality Awareness and Self-Advocacy

Nestor advocates awareness of environmental breathing conditions. Using affordable CO2 monitors, individuals can assess indoor air quality and advocate for better ventilation in schools, workplaces, and homes. Fresh air intake improves cognitive performance, mood, and overall health. Simple actions—like opening windows, investing in air purifiers, or negotiating work environments—can make meaningful differences in daily well-being.

Ancient Wisdom and Modern Science on Breath

Throughout the conversation, Nestor reflects on the convergence of ancient breathing traditions—yogic prana, Chinese chi, and Tibetan meditation—with modern physiological research. While certain mystical claims remain scientifically unproven, the undeniable subjective experiences of energy alteration and mental clarity corroborate the power of breath practice. The balance of rigorous scientific measurement and acknowledgment of breath's subtler, ineffable qualities enriches understanding and practice.

James Nestor's Personal Journey and Reflections

Nestor shares his own transformational journey from chronic respiratory illness to breathwork enthusiast, emphasizing the profound health improvements he experienced after retraining his breath. He reflects on the cultural and institutional hurdles to widespread adoption of these insights, citing frustration with slow medical acknowledgment despite compelling evidence. He underscores the importance of accessible education and empowering individuals to take charge of their respiratory health through practical tools and awareness.

Practical Immediate Actions

For listeners eager to start improving their breathing, Nestor suggests beginning by recording sleep patterns using apps like SnoreLab to identify breathing disruptions. From there, simple daily practices like nasal breathing during routine activities, mindfulness of posture, gradual adaptation to mouth tape at night, and breath-hold exercises can build a solid respiratory foundation. Early engagement with pediatric dental airway specialists is encouraged to mitigate developmental issues in young children.

Breath Control for Anxiety and Stress Management

As a powerful non-pharmaceutical tool, controlled breathwork can quickly calm acute anxiety and stress. Techniques involving slow, rhythmic nasal inhalations coupled with breath holds provide immediate downregulation of the nervous system. Regular practice builds resilience and reduces the frequency of panic episodes by enhancing CO2 tolerance and improving autonomic balance.

Breathwork Stress and Relaxation Cycles

Vigorous breathing methods like Wim Hof and holotropic breathing intentionally induce short-term physiological stress to provoke adaptive responses. These controlled exposures allow practitioners to reset nervous system patterns and achieve states of deep relaxation. Such practices, however, should be approached carefully by those with dysfunctional breathing fundamentals, as misapplication can exacerbate health issues.

Breathing and Mental Clarity

Better oxygen and CO2 balance derived from proper breathing supports enhanced cognitive function, alertness, and mood regulation. This has implications across age groups from school performance to aging populations managing dementia risk. Ensuring a balance between breath rate, depth, and nasal filtration governs not only physical but also mental well-being.

Breath Control's Role in Childhood Development

Early life is critical for establishing healthy breathing patterns. The link between obstructed nasal breathing, craniofacial development, sleep quality, and neurodevelopment highlights a largely underappreciated factor in pediatric health and behavior. Nestor stresses parental awareness and intervention as vital steps to improve lifelong outcomes.

Closing Thoughts on Breath Awareness Movement

The episode concludes with reflections on the emergence of breathing awareness as a health discipline and cultural phenomenon, acknowledging both successes and challenges. Nestor sees the growing interest as a hopeful sign but implores listeners to prioritize foundational breathing health over faddish trends, emphasizing that most people can benefit enormously from simple, consistent habits fostering nasal, diaphragmatic, and slow breathing patterns.