The Science of Nasal Breathing: A Path to Reducing Chronic Stress

Chronic stress has become a hallmark of modern life, contributing to a host of health problems such as anxiety, cardiovascular disease, and weakened immunity. While mindfulness, exercise, and nutrition are widely advocated as remedies, a simple yet powerful solution is often overlooked: nasal breathing. This natural and ancient practice offers profound benefits for people dealing with chronic stress. Drawing on insights from James Nestor’s Breath and Patrick McKeown’s The Oxygen Advantage, this article explores the science behind nasal breathing and its transformative potential for reducing stress, with special attention to the role of diaphragmatic breathing in improving oxygen efficiency.

The Forgotten Power of Nasal Breathing

Breathing through the nose, rather than the mouth, is a practice rooted in both biology and tradition. The nose functions as more than an airway—it filters, humidifies, and regulates the air we breathe, enhancing oxygen delivery to the body and brain.

As early as the 19th century, George Catlin observed the importance of nasal breathing. In his 1861 paper, Shut Your Mouth and Save Your Life, Catlin documented how Indigenous peoples emphasised nasal breathing for better health and longevity. He even documents parents gently closing the mouths of their sleeping infants to ensure nasal breathing. Despite his efforts to promote this simple practice, much of society has shifted to mouth breathing, with significant consequences for health. Fortunately, modern science has revived interest in nasal breathing and its benefits, especially for those suffering from chronic stress.

How Nasal and Diaphragmatic Breathing Alleviate Stress

1. Improved Oxygen Delivery

A key benefit of diaphragmatic breathing, facilitated by nasal breathing, is its ability to direct airflow to the lower regions of the lungs. This is significant because perfusion (the flow of blood through the lungs) is greatest at the lung bases due to gravity. This means that the lower portions of the lungs are where gas exchange is most efficient, when air is able to reach them.

Shallow breathing through the mouth typically directs airflow to the upper portions of the lungs, where perfusion is less effective. Over time, this inefficient oxygen exchange can exacerbate feelings of breathlessness, anxiety, and fatigue—common symptoms of chronic stress.

By encouraging diaphragmatic breaths through the nose, individuals can improve oxygen delivery to the lung bases. This not only enhances oxygen uptake and improves gas exchange, but also reduces the physiological strain associated with stress, promoting a greater sense of calm and well-being. James Nestor explains in Breath that diaphragmatic breathing creates a synergy between oxygen supply and demand, helping the body achieve balance even in moments of heightened stress.

2. Regulation of Oxygen and Carbon Dioxide Levels

One of the core principles discussed in The Oxygen Advantage is the importance of maintaining balanced levels of oxygen and carbon dioxide (CO₂) in the bloodstream. Mouth breathing often leads to over-breathing or hyperventilation, disrupting this balance and reducing the efficiency of oxygen delivery to cells. This is due to the reduction in CO₂ seen during over-breathing.

Adequate CO₂ in the bloodstream is essential to ensure optimal oxygen delivery at a cellular level. This utilises the Bohr effect—a phenomenon whereby higher CO₂ in the blood causes haemoglobin (a protein responsible for carrying over 98% of oxygen in the blood) to offload oxygen more readily to the tissues, where it is most needed.

Nasal breathing helps to slow the breath, ensuring optimal CO₂ retention and therefore oxygen delivery. This balance calms the nervous system and counters the physiological effects of chronic stress, such as increased heart rate, muscle tension and anxiety.

3. Activation of the Diaphragm and Parasympathetic Nervous System

Nasal breathing naturally engages the diaphragm, a dome-shaped muscle that plays a central role in respiration. Diaphragmatic breathing stimulates the parasympathetic nervous system, which is responsible for the “rest-and-digest” state. This reduces cortisol levels, slows the heart rate, and promotes relaxation.

In contrast, shallow, chest-dominant mouth breathing activates the sympathetic nervous system, exacerbating the fight-or-flight response that accompanies chronic stress. Patrick McKeown highlights how diaphragmatic breathing through the nose can shift the body from a state of hyperarousal to one of equilibrium.

4. Boosts Nitric Oxide Production

The nasal passages produce nitric oxide, a molecule with remarkable health benefits. It acts as a vasodilator, improving blood circulation and oxygen delivery throughout the body. Nitric oxide also has antimicrobial properties, potentially strengthening the immune system—a critical factor for those dealing with the immune suppression often caused by chronic stress.

James Nestor emphasises that nitric oxide plays a key role in improving brain function, memory, and emotional stability. For individuals suffering from stress, this enhanced brain oxygenation can improve focus and overall mental well-being.

Everyday Applications of Nasal and Diaphragmatic Breathing

The Stressed Worker

Working in Western society is increasingly demanding, and a huge proportion of people report feelings of stress and overwhelm. Just look at the NHS—almost everyone is on the verge of burnout. Common issues, such as deadlines, long meetings, high-pressure work environments, poor staffing levels and increasingly unrealistic expectations can drive up stress levels. Nasal breathing, practised for even five minutes at a time can lower cortisol levels, improve mental clarity, improve productivity and most importantly- reduce stress and anxiety.

The Busy Parent

Parents juggling family responsibilities often feel overwhelmed. Practising nasal breathing during routine tasks like cooking or folding laundry can instil calmness amidst a hectic schedule.

The Fitness Enthusiast

Athletes and fitness lovers benefit greatly from nasal breathing. It is definitely worthy of an article of its own. It enhances endurance, reduces fatigue, and accelerates recovery by improving oxygen efficiency. Both Nestor and McKeown recommend nasal breathing as an essential aspect of physical performance.

The Sleep-Deprived Individual

For those struggling with insomnia or poor-quality sleep, practising nasal and diaphragmatic breathing techniques before bedtime can promote relaxation and set the stage for restorative rest.

A Modern Solution to a Timeless Problem

In a fast-paced world filled with mounting pressures, nasal breathing offers a surprisingly simple yet powerful antidote to chronic stress. The research and insights from James Nestor, Patrick McKeown, and even George Catlin remind us of the importance of reconnecting with this fundamental human practice.

Whether it’s directing airflow to the lung bases for optimal oxygen exchange, calming the nervous system, or improving sleep, the benefits of nasal breathing extend to every aspect of life. By making this small adjustment, individuals can unlock greater health, focus, and resilience—one breath at a time.

Breathing at R1SE

The use of the breath is central to all that R1SE is. At its core- breathing is simple- we breathe about 20,000 times each day. However, learning to breathe efficiently and use the breath for what it can achieve is quite simply remarkable and the benefits are potentially profound. R1SE is committed in the use of and education about breath work, hoping to bring its benefits to many more people.

Chris and Tim also have a wonderful trip to Galway in Ireland to look forward to in March 2025. They’re embarking on an advanced instructor course, run by ‘the man himself’ Patrick McKeown. This enhanced knowledge and how it can apply to all the different people at R1SE will be put to great use in the coming months and years. A truly exciting year ahead on the breathing front!