Breathe Better: How Breathing Shapes Digestion, Hormones, Focus and Recovery
Breathing is the most vital function of the body—and the most overlooked. We breathe around 20,000 times a day, and most people already achieve 97–99% oxygen saturation and use up to 80% of their lung capacity. So when we practise breathwork, we’re not aiming to increase oxygen or lung size.
The real transformation happens elsewhere: in the balance between oxygen and carbon dioxide (CO₂), the pressure regulation inside the body, and our ability to influence the autonomic nervous system. Breathing well improves:
- Digestion
- Stress recovery
- Cardiovascular health
- Sleep
- Hormonal regulation
- Focus and energy levels
This article offers a practical, science-based approach to breath—integrating insights from anatomy, physiology, and clinical applications. You’ll learn how breath acts as the bridge between body and brain—and how just five minutes, three times per day can radically improve your health.
Poor breathing habits develop gradually. Chronic stress, posture issues, lack of awareness, and even early-life mouth breathing can train the body into a pattern of shallow, fast, upper chest breathing. This kind of breathing keeps cortisol levels high, increase vasoconstriction leading to an elevated heart rate as well as inhibiting metabolism, influencing muscle- and bonemass, blood sugar regulation and hormonal balance.— Over time, it becomes the default, unconscious pattern used during sleep and rest.
Why How We Breathe Matters
Breathing is unique: it’s controlled by the autonomic nervous system, like heartbeat and digestion, but carried out by skeletal muscles—primarily the diaphragm and assisted by intercostals, scalenes, and others. This means we can train our breathing, and in doing so, access internal systems typically outside of conscious control.
Poor breathing habits develop gradually and unconsciously. Chronic stress, postural changes, and mouth breathing lead to rapid, shallow upper-chest breathing. This type of breath increases sympathetic tone, raises cortisol, and alters our baseline physiology—even when no real threat is present.
When we restore proper breath mechanics—slower, nasal, diaphragmatic—we are able to regulate our nervous system optimising function throughout the whole body across all systems. This shift affects:
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Heart rate
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Blood pressure
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Hormone secretion
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Mental clarity
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Gut Health
- Muscle and Bone Health
- Cognitive Health
In short: how we breathe shapes how we live.
It’s Not About Oxygen – The Importance of CO₂ and O₂
The human body is rarely short on oxygen. The real key to efficient respiration is carbon dioxide (CO₂)—a molecule often misunderstood but absolutely vital to health.
CO₂ plays three essential roles:
pH regulation – Maintains the blood’s acid–base balance between 7.35–7.45
Oxygen delivery – Via the Bohr effect, CO₂ helps haemoglobin release oxygen to tissues
Vasodilation – CO₂ relaxes smooth muscle in blood vessels and bronchioles
When you over-breathe or breathe too fast, CO₂ is exhaled too quickly. This causes:
Vasoconstriction (narrowing of blood vessels)
Increased blood pressure and heart rate
Reduced oxygen delivery to the brain and muscles
Dizziness, fatigue, anxiety and cold extremities
📌 Key Point: We are not oxygen-deficient. We are often CO₂-intolerant—and that’s the real problem.
CO₂, Blood pH, and Pressure Dynamics
Every breath influences your blood chemistry. CO₂ is acidic, and when you exhale, your body becomes slightly more alkaline. Too much exhalation (hyperventilation) leads to respiratory alkalosis—a temporary spike in pH that can cause:
- Tingling or numbness
- Muscle tension or cramps
- Brain fog or light-headedness
- Poor emotional regulation
Beyond chemistry, breath also affects internal pressure dynamics. When you inhale, the diaphragm contracts downward, creating a negative pressure in the thoracic cavity. This draws blood up from the lower body toward the heart, aiding circulation.
These internal pressure changes help:
- Venous return (blood from the legs and organs)
- Lymphatic drainage (waste removal and immune transport)
- Cerebrospinal fluid circulation (brain and spine)
- Organ mobility and function (via diaphragmatic massage)
📌 In summary: Breath is not just about gas exchange—it’s a pressure pump that supports circulation, detoxification, immune flow, and organ health.
The Bohr Effect: How CO₂ Controls Oxygen Delivery
At the centre of healthy breathing is a principle known as the Bohr effect—a physiological law that explains how carbon dioxide (CO₂) helps oxygen (O₂) reach your cells.
Oxygen doesn’t move directly from the lungs into your tissues. Instead, it first binds to haemoglobin, the protein in red blood cells responsible for oxygen transport.
Haemoglobin acts like a taxi, picking up oxygen in the lungs and releasing it into tissues like the brain, muscles, and organs.
But here’s the key:
Haemoglobin will only release oxygen when CO₂ is present. CO₂ will bind to the haemoglobin and thereby release the O₂ to the cells. This is why, when we breathe fast and shallow, like in breath of fire or if we are having an astma or a panic attack, we faint. We faint because we get too little oxygen to the brain. When we breathe into a bag, we breathe in the same air multiple times, and that air will be saturated with more CO₂, which when we breathe again and again in the same bag, we increase CO₂ in out blood and then increase oxygen delivery to cells.
This is the Bohr effect in action. Discovered by Christian Bohr in 1904, the effect describes how an increase in CO₂ (and a slight drop in pH) reduces haemoglobin’s affinity for oxygen, allowing oxygen to be released where it is needed.
In simple terms:
More CO₂ = more oxygen released to your tissues
Less CO₂ = oxygen stays bound to haemoglobin and is not delivered efficiently
This means that breathing too fast or too shallow—especially through the mouth—causes CO₂ levels to drop, which in turn prevents oxygen from reaching the brain and muscles, even if your blood is saturated with oxygen
📌 Key Outcomes of the Bohr Effect:
CO₂ makes oxygen delivery possible
Low CO₂ leads to poor oxygenation, especially in the brain, heart, and muscles
Breath-holding and slow breathing increase CO₂ levels, improving oxygen use
Over-breathing (hyperventilation) can reduce brain oxygen by up to 40% in under a minute
In breath training, we’re not trying to get more oxygen into the blood—we’re learning to tolerate CO₂ so that the oxygen we already have can be used by the body effectively. This shift has profound effects on physical endurance, mental clarity, and stress regulation.
Breathing Reflexes, the Diaphragm, and the Phrenic Nerve
Breathing is not triggered by a lack of oxygen. It is initiated by rising levels of CO₂, which acidify the blood. When CO₂ reaches a certain threshold, this triggers an exhalation to restore pH balance.
This reflex is managed by chemoreceptors in the medulla and carotid bodies, and sent to the diaphragm via the phrenic nerve (C3, C4, C5). Even in cases where brain function is compromised, spinal reflexes can preserve breathing.
The diaphragm is the main muscle of respiration. As a skeletal muscle, it can be trained. Overuse of accessory muscles (neck, shoulders, chest) can result in inefficient, stressful breathing patterns—especially when this becomes habitual.
Fast, shallow breathing lowers CO₂ tolerance over time. The body learns to exhale too soon, retraining the brain to associate fast, shallow breath as "normal." This often carries into sleep, leading to poor rest and sympathetic dominance overnight.
To reverse this, breathing practices must include:
- Specific practices for morning, midday and evening.
- Mostly nasal breathing
- Breath-holding exercises (to retrain CO₂ tolerance and reset reflex thresholds)
Breath, Nervous System Regulation, and Smooth Muscle
Breath gives us direct access to the autonomic nervous system (ANS), which controls internal processes like:
- Heart rate and rhythm
- Digestion and elimination
- Immune activation
- Hormonal output
- Smooth muscle tone
Each breath shifts the body between two modes:
- Sympathetic (fight or flight): fast, shallow, mouth breathing
- Parasympathetic (rest and digest): slow, deep, nasal breathing
The vagus nerve is central to this regulation. It travels from the brainstem to the major organs, relaying information and helping to reduce inflammation, promote digestion, and regulate emotional tone.
Breathing also affects smooth muscle, found in:
- Blood vessels (vasodilation/constriction)
- Bronchioles (airway openness)
- Digestive tract (motility)
- Bladder and uterus (tone and contraction)
📌 Parasympathetic breathing = smooth muscle relaxation 📌 Sympathetic breathing = smooth muscle tension
Nose vs. Mouth Breathing
The nose is your body’s primary breathing organ. It does far more than allow airflow:
Benefits of Nasal Breathing:
- Filters particles, dust, and microbes
- Warms and humidifies incoming air
- Produces nitric oxide (NO) to increase vasodilation optimising oxygen delivery
- Stimulates diaphragmatic breathing and vagal tone
- Supports jaw and airway development in children
- Enhances sleep, emotional regulation, and focus
❌ Risks of Mouth Breathing:
- Bypasses filtration and humidification
- Reduces NO, oxygen efficiency, and immune defence
- Encourages shallow, fast breathing
- Increases risk of dental issues and airway collapse
- Associated with snoring and poor sleep quality
📌 If you mouth-breathe during sleep, try:
- Mouth tape or chin strap
- Nasal dilators or saline rinse
- Side-sleeping position
- Breath training during the day
Night-Time Breathing: The Unconscious Third
You breathe for a third of your life while asleep. Yet many people unknowingly breathe through their mouths at night—disrupting recovery, oxygenation, and hormonal balance.
Common signs of disordered night breathing:
- Dry mouth or throat in the morning
- Snoring or disturbed sleep
- Fatigue even after 8 hours in bed
Night-time breathing impacts:
- Cortisol–melatonin rhythms
- Dopamine and testosterone production
- Immune repair and cellular recovery
- Nervous system reset and memory consolidation
Training your breath during the day improves unconscious breathing at night. When needed, use gentle tools to support nasal breathing and improve sleep quality—because night-time breath matters as much as daytime technique.
How Should I Breathe? – The Coffee–Water–Whiskey Method
There are a ton of different breathing exercises, and knowing which one to use when can be a challenge. Luckily, all breathing practices belong to only one of three categories. Once you know the three categories, you will be able to know what each breathing practice will do for your health.
The difference breathing practices are put into one of the following three categories depending on the breathing rate and ratio.
☕ Coffee Breathing (Morning / Pre-workout)
- Fast, energising breath (e.g. Breath of Fire)
- 30+ breaths/minute - So rapid breathing
- Stimulates cortisol and alertness
- Activates the diaphragm and clears grogginess
- Perfect for the morning, just like a cup of coffee
💧 Water Breathing (Midday / Stress Reset)
- Coherent, rhythmic breathing (e.g. Box breathing)
- 4-6 breath /minute - which is half speed of an average breathing person
- Balances nervous system and supports digestion
- Calms anxiety and resets focus
- Like a glass of water, perfect for any time of the day
- Often used midday to regulate nervous system, bringing energy levels up if feel tired or grounding when feeling wired.
🥃 Whiskey Breathing (Evening / Wind Down)
- Slow, extended exhales (e.g. 4:8 breathing, Brahmari, physiological sigh)
- 4 or less breath/minute
- Reduces cortisol and prepares for sleep
- Promotes vagal tone and limbic calming
- increases CO2, relaxes smooth muscles and sends body into rest and digest mode
Use these tools strategically throughout your day to support mood, mental clarity, and recovery.
Test Your Breath – And Improve It Day by Day
Measuring your CO₂ tolerance gives insight into your nervous system and breath function. It is great to begin with testing your breath, so that you can see how you improve over time.
CO2 Tolerance Test
- Breathe normal three times
- Normal exhale → then hold breath
- Count seconds until first urge to breathe
Check Your Score:
- 0–10 seconds - Very low CO₂ tolerance – dysfunctional breathing, often linked to stress, fatigue, poor sleep
- 11–20 seconds - Below average – frequent over-breather, likely mouth breathing or poor unconscious patterns
- 21–40 seconds- Functional range – good baseline; still room to improve autonomic regulation and energy efficiency
- 41–60 seconds - Very good – strong CO₂ tolerance, likely good breath habits, nervous system balance, and vagal tone
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60+ seconds - Excellent – elite level of breathing control, resilience, and energy economy
Breath Control Test
- Breathe normal three times
- Now inhale as much as you can
- Exhale while counting with a whispering voice.
Check Your Score: -Exhale Duration Interpretation
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<10 seconds -Weak diaphragm tone, very poor breath control or CO₂ sensitivity
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10–20 seconds - Developing control – some CO₂ tolerance, but still easily overstimulated
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21–30 seconds - Functional – indicates developing parasympathetic access and muscle control
- 31–45 seconds - Strong – efficient diaphragm use, healthy CO₂ processing, high vagal tone
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45+ seconds - Excellent – elite breathing regulation, strong diaphragm, very calm nervous system
📌 You can improve both scores in just a few weeks with daily practice.
Breath is more than air in and out—it is a full-body, full-system regulator.
It affects your blood chemistry, your heart rhythm, your emotional tone, your digestion, your circulation, and your sleep. And best of all, it’s trainable.
By spending just five minutes each morning, midday, and evening, you can:
- Improve your nervous system balance
- Restore deep, efficient unconscious breathing
- Optimise digestion, recovery, and sleep
- Prevent chronic fatigue, anxiety, and burnout
Train your breath. Rebuild your rhythm. Reset your system—one exhale at a time.