FUNCTIONAL BREATHING
How you breathe determines
how your nervous system operates
Breathing is the only autonomic function you can also control consciously. That makes it both a sensor — showing you the state of your system — and a lever for changing it.
THE BASICS
Breathing that supports regulation, not undermines it
Most people don't have a breathing problem. They have a breathing pattern — one that developed in response to stress, posture, habit, and years of sympathetic activation. That pattern now runs in the background, shaping how their nervous system responds to everything.
Functional breathing means three things: nasal breathing as the default (filtering, humidifying, and producing nitric oxide for vasodilation), diaphragmatic breathing that engages the lower lungs where gas exchange is most efficient, and a breathing rate that matches what your system actually needs — typically 4.5 to 6.5 breaths per minute at rest for most adults.
When these three are in place, your autonomic nervous system has the foundation it needs to regulate properly. When they're not, your system is compensating — often without you knowing it.
CARBON DIOXIDE TOLERANCE
The metric most people haven't heard of — and the one that matters most
CO₂ is not just a waste gas. It's a primary driver of how your body delivers oxygen to tissues. The Bohr effect — first described in 1904 — shows that haemoglobin releases oxygen more efficiently in the presence of adequate CO₂. When you overbreathe (which most stressed people do, often without realising), you blow off CO₂ and paradoxically reduce oxygen delivery to the brain, muscles, and organs.
CO₂ tolerance is the measure of how comfortable your system is with normal levels of carbon dioxide. Low tolerance means your system triggers the urge to breathe too early, maintaining a cycle of overbreathing that keeps your sympathetic nervous system activated.
Training CO₂ tolerance is one of the most efficient ways to shift your nervous system baseline. It's measurable, it's progressive, and the effects show up in sleep, decision-making, and recovery within days.
Slow breathing techniques enhance autonomic, cerebral, and psychological flexibility.
ZACCARO ET AL., FRONTIERS IN HUMAN NEUROSCIENCE, 2018
Nasal breathing activates the diaphragm more effectively and increases parasympathetic activity compared with oral breathing.
DIEST ET AL., PSYCHOPHYSIOLOGY, 2020
FROM SENSOR TO LEVER
Breath as a window into your nervous system state
As a sensor: Your breathing pattern right now tells you about your autonomic state. Shallow, fast, upper-chest breathing signals sympathetic dominance. Slow, nasal, diaphragmatic breathing signals parasympathetic engagement. Before any intervention, the breath is the data.
As a lever: Because breathing operates at the intersection of voluntary and involuntary control, you can use it to shift your state deliberately. A physiological sigh (double inhale through the nose, extended exhale through the mouth) can downregulate your system in under 30 seconds. A deliberate increase in breathing rate can sharpen focus before a presentation.
This is not philosophy. It's respiratory physiology applied to real-world conditions.
Cyclic sighing for five minutes daily produced greater improvement in mood, reduced anxiety, and improved physiological calm compared to mindfulness meditation.
HUBERMAN LAB / STANFORD, BALBAN ET AL., CELL REPORTS MEDICINE, 2023
WHAT THIS ISN'T
The distinction that matters
Functional breathing is not breathwork in the way that term is commonly used. It's not hyperventilation, cathartic release, or altered states of consciousness. Those modalities exist and have their place — but they're not what this work is built on.
Functional breathing is closer to exercise physiology than to ceremony. It's evidence-based, measurable, progressive, and designed to produce lasting change in your nervous system's resting state. It draws on the Oxygen Advantage methodology, respiratory physiology research, and clinical applications of breathing pattern assessment.
The goal is not a peak experience during a session. The goal is a better baseline for the other 23 hours of your day.