Most of us go through the day without thinking much about our breath. Inhale, exhale, repeat. But the way we breathe impacts nearly every system in the body, from sleep and stress levels to energy, endurance, and long-term health. Breath experts such as Patrick McKeown (creator of Oxygen Advantage®), James Nestor, and Brian Mackenzie all share a consistent message:

How you breathe matters. And your nose is your primary breathing organ.

If you rely on mouth breathing, especially during sleep, stress, or exercise, you’re not alone. It’s common, but it’s also trainable. With awareness and simple techniques, nose breathing becomes a habit that supports better health, performance, and overall well-being.

Why the Nose Is Designed for Breathing

The nose performs dozens of critical functions that support respiratory health and efficient breathing. According to the Oxygen Advantage®, nasal breathing helps to:

• Filter bacteria, viruses, and environmental debris
• Warm and humidify incoming air
• Protect the airways and lungs
• Increase nitric oxide production, supporting oxygen delivery and immune function
• Encourage diaphragmatic breathing and reduce upper-chest breathing patterns

Mouth breathing bypasses these essential functions. Without proper filtration and pressure regulation, the body works harder to maintain oxygen balance, often activating stress pathways and influencing sleep, dental health, and respiratory efficiency. James Nestor highlights this extensively in his bestselling book Breath: The New Science of a Lost Art, noting that habitual mouth breathing can contribute to airway restriction, inflammation, poor sleep, and reduced overall vitality.

How Nose Breathing Supports Functional Breathing

Functional breathing involves breathing through the nose, using the diaphragm effectively, and maintaining quiet, light, efficient breathing, especially at rest. Nasal breathing naturally supports all three.

Improved Oxygen Delivery

Although it may feel counterintuitive, breathing less air, when done correctly, helps you deliver more oxygen to your cells. This is based on the Bohr Effect, a principle highlighted in the Oxygen Advantage method: balanced CO₂ levels improve oxygen release within tissues. Mouth breathing often leads to over-breathing, reducing CO₂ levels and limiting oxygen delivery.

Lower Stress and Improved Emotional Regulation

The breath is one of the most direct pathways into the nervous system. Nasal breathing supports diaphragmatic engagement, signaling safety to the brain and activating parasympathetic pathways. Brian Mackenzie refers to nasal breathing as the “governor of the stress response,” helping stabilize physiological reactions during rest, work, and training.

Better Sleep Quality

Consistent mouth breathing at night can contribute to snoring, fragmented sleep, poor morning energy, and increased sympathetic activation. Nasal breathing promotes smoother airflow, supports nitric oxide production, and enhances sleep quality. Many individuals find that simple nasal-supportive strategies, such as gentle mouth tape, create noticeable improvements in morning energy and overall recovery.

Enhanced Immunity and Reduced Inflammation

The nasal cavity is the body’s first line of respiratory defense. When air enters through the nose, it is filtered, warmed, humidified, and enriched with nitric oxide, a naturally occurring molecule with antimicrobial properties. This creates a healthier environment for the lungs and supports immune function.

Improved Exercise Performance and Faster Recovery

Nasal breathing has been shown to improve cardiovascular efficiency, reduce ventilation rates, and increase CO₂ tolerance. As Brian Mackenzie teaches in his work on breath-adaptation training, nasal breathing during movement helps:

• Lower heart rate at similar intensities
• Improve endurance
• Reduce perceived exertion
• Enhance aerobic development
• Accelerate recovery after exertion

By training the breath, you train your physiology, just as you would train muscles or mobility patterns.

Nose Breathing Can Be Trained

Breathing patterns are habits. With the right tools and consistency, nose breathing becomes effortless.

Awareness

Noticing when you shift into mouth breathing at rest, during stress, or during exercise is the first step in retraining the pattern.

Resting Breathwork

Practices that emphasize light, slow nasal breathing help restore functional patterns and create a calmer internal environment.

CO₂ Tolerance Training

Breath-hold practices and controlled nasal breathing exercises, introduced in methods like Oxygen Advantage®, support improved comfort with nasal breathing and reduce “air hunger” during activity.

Movement With the Mouth Closed

Walking, lifting, or running with nasal breathing teaches the body to stabilize internally, improving efficiency and establishing long-term breathing resilience.

Sleep Support

Gentle strategies to promote nasal breathing overnight help restore natural rhythms and significantly improve recovery and energy.

As James Nestor writes, “The breath is malleable.” With practice, you can reshape how you breathe—and dramatically change how you feel.

Why Nose Breathing Matters for Overall Well-Being

The science, clinical experience, and real-world application all point to the same conclusion: nasal breathing supports a healthier, more resilient body.

Benefits include:

• Improved cardiovascular function
• Greater cognitive clarity and focus
• Reduced anxiety and emotional reactivity
• Better posture and rib mobility
• Balanced respiratory patterns
• Enhanced digestive support
• Stronger immunity
• Longevity and healthier aging

The breath is a gateway to resilience. Nose breathing is the foundation.

A Simple Technique, A Powerful Shift

Breath training doesn’t need to be complicated. It begins with a single choice:

Close your mouth. Breathe through your nose. Keep your breath quiet, light, and steady.

Over time, your body adapts.

Your sleep improves.

Your endurance builds.

Your stress decreases.

Your energy increases.

Your overall health shifts in a meaningful way.

This is functional breathing.

This is accessible to everyone.

And this is something you can train.

Building the Habit

Like any meaningful lifestyle change, nose breathing becomes easier through repetition and consistency. At first, you may need reminders, during rest, during movement, or when stress rises. But as you practice, the neural pathways supporting nasal breathing strengthen. What begins as a conscious effort gradually becomes automatic. With small, consistent practices throughout the day, nose breathing becomes your default pattern, a reliable, built-in tool that supports better health, performance, and longevity.

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References

McKeown, P. The Oxygen Advantage. William Morrow Paperbacks, 2015.

Nestor, J. Breath: The New Science of a Lost Art. Riverhead Books, 2020.

Lundberg, J. “Nitric Oxide and the Nose.” Annual Review of Physiology, 2018.

Dallam, G. et al. “Nasal Versus Oral Breathing During Exercise: Implications for Efficiency and Performance.” International Journal of Kinesiology & Sports Science, 2018.

Mackenzie, B., & Cotter, J. UnPlugged & Shift Adaptation Training Resources, Shift/Power Speed Endurance.