Breathwork and nervous system regulation

Nervous system regulation has become a familiar phrase in the wellness space. Given how many demands compete for our attention, I can understand why.

Messages arrive throughout the day. Work follows us home. The digital world keeps expanding, and artificial intelligence is accelerating the pace again. There is always something else to respond to, learn or keep up with.

Against that background, the promise of feeling calmer is understandably appealing.

But in the breathwork space, nervous system regulation is often reduced to one transition: moving from stressed to relaxed.

I think that misses something important.

Regulation is also about having the capacity to experience activation, emotion and physical demand while retaining enough flexibility to respond to what is happening.

That might mean sitting with a difficult feeling. It might mean communicating with your partner during an argument. Or it might mean performing in sport when your heart is racing and the outcome matters.

None of those situations requires you to feel completely calm.

What does nervous system regulation actually mean?

There is no single wellness definition that captures everything the nervous system does. We need to be clear about what we mean.

The body already regulates itself continuously. Homeostasis describes the processes that maintain internal conditions within viable ranges, including temperature, blood gases and acid–base balance.

That automatic physiological regulation is related to, but not identical to, our ability to manage attention, emotion and behaviour.

When I talk about regulation in practice, I am interested in a person’s ability to respond flexibly to the demands in front of them. Can they mobilise when something requires action? Can they recover when that demand passes? Can they remain engaged with what matters while experiencing discomfort?

That is a broader question than whether their heart rate has slowed.

A person can be quiet and still yet feel disconnected or unable to act. Someone else can be highly activated and remain focused, responsive and effective.

The level of activation matters. So does what the person can do within it.

Sympathetic and parasympathetic activity are only part of the picture

We often hear that the sympathetic nervous system is the accelerator and the parasympathetic nervous system is the brake.

As an introduction, that analogy has some value. Taken too literally, it becomes misleading.

These systems regulate different organs in different ways. They do not function as two global switches, with one representing stress and the other representing safety.

The wider nervous system also supports perception, movement, attention, memory, learning and the interpretation of bodily signals.

If someone feels anxious before speaking publicly, their experience cannot be explained entirely by sympathetic activation. What they anticipate, what happened during previous presentations and how they interpret a racing heart may all influence their response.

This is why I am cautious about treating every uncomfortable sensation as evidence that someone’s nervous system is “dysregulated”.

Sometimes activation is appropriate. Sometimes the difficulty is its intensity, duration or the person’s ability to respond to it.

From a window of tolerance to a window of capacity

The window of tolerance is a useful clinical model for discussing a range of arousal within which someone can remain engaged and respond flexibly.

I find “window of capacity” a helpful way to think about it, because it directs attention towards what a person can manage and do.

At one extreme, someone may feel overwhelmed, agitated or unable to think beyond an immediate threat. At another, they may feel disengaged, slowed down or disconnected.

But the window is a model, not a physiological measurement. We cannot identify its exact boundaries from a wearable, a breathing pattern or one observation. Nor should we assume that avoidance, stillness or fatigue maps neatly onto a particular autonomic state.

The practical question is: What level of demand can this person engage with while retaining choice and flexibility?

That capacity may change with context, sleep, health, familiarity and the demands of the day.

How does breathing influence nervous system regulation?

Breathing is unusual because it happens automatically, yet we can also change it voluntarily.

Changing breathing can influence ventilation, cardiovascular activity, respiratory sensations and attention. These influences overlap, but they are not interchangeable.

Breathing and arousal

The locus coeruleus is the principal source of noradrenaline supplying widespread regions of the brain, including the cortex. Noradrenaline, also called norepinephrine, helps modulate arousal, attention and how we respond to important events.

A 2017 study by Yackle and colleagues identified neurons in the mouse pre-Bötzinger complex, a region involved in generating breathing rhythm, that connect directly with noradrenergic neurons in the locus coeruleus. This established a circuit through which breathing-related activity can influence arousal.

There is complementary human evidence. Melnychuk and colleagues’ 2018 study reported synchronisation between respiration and LC-related activity using fMRI and pupil measurements, alongside relationships with attentional performance. Their 2021 research examined coupling between breathing, pupil diameter and an EEG marker of attentional control.

Together, these findings support a connection between breathing, noradrenergic arousal and attention. The human studies do not directly trace the same circuit or measure noradrenaline release, so we should keep that distinction clear.

For practice, the point is that breathing can interact with systems involved in how alert and attentive we feel. That does not mean faster breathing invariably creates anxiety or that slower breathing invariably produces calm. Fast breathing can accompany exercise, excitement or fear. Its meaning depends on the situation, and breathing frequency alone tells us relatively little about total ventilation.

Carbon dioxide and air hunger

Carbon dioxide is central to respiratory control. It is not simply a waste gas, and it is not a reliable calming agent either.

Its effects depend on the starting conditions, the size and speed of the change, and the individual.

If someone is overventilating and has reduced their CO₂ below its usual range, reducing excessive ventilation may help restore it. That is different from deliberately increasing CO₂ in someone whose blood gases are already appropriate.

Rising respiratory drive, particularly when breathing does not provide sufficient relief, can contribute to air hunger: the uncomfortable sense of needing more air.

Banzett, Lansing and Binks’ review of air hunger describes it as a powerful sensation that motivates behaviour to protect gas exchange. It can evoke fear and anxiety, but air hunger and panic are not the same experience.

We should therefore be cautious about describing uncomfortable breath holds as automatically beneficial “CO₂ tolerance training”.

I explore this in more detail in The Truth About CO₂ Tolerance: Breath-Hold Time, Nasal Breathing and the Bohr Effect.

Breathing and heart rate variability

Heart rate commonly increases during inspiration and decreases during expiration. This breathing-related variation is called respiratory sinus arrhythmia.

Its mechanisms include changes in cardiac vagal activity, central respiratory influences, pressure changes and cardiovascular reflexes. The arterial baroreceptors are located principally in the carotid sinuses and aortic arch; their signals are processed in the brainstem.

The physiology is more involved than a simple “inhale activates stress, exhale activates calm” explanation.

As Grossman and Taylor discuss, breathing and cardiovascular mechanisms complicate the interpretation of respiratory sinus arrhythmia as a measure of vagal activity.

This matters when we measure heart rate variability during breathing exercises. A larger oscillation during slow breathing does not, by itself, demonstrate better emotional regulation or lasting resilience.

For more on that distinction, see When Higher HRV Isn’t Better: Interpreting Heart Rate Variability in Context.

What does research actually show about breathwork and stress?

There is evidence that breathing practices can help with subjective stress. We should also be honest about what that evidence establishes.

A 2023 meta-analysis by Fincham and colleagues found a small-to-moderate average benefit for self-reported stress across 12 randomised controlled trials. The authors also highlighted concerns about study quality and the need for more robust research.

Later that year, a randomised placebo-controlled trial involving 400 participants compared coherent breathing at approximately 5.5 breaths per minute with an attention-matched breathing practice at 12 breaths per minute.

Participants practised for approximately 10 minutes a day over four weeks. Both groups improved, but coherent breathing did not produce greater improvements in stress or the other measured mental health and wellbeing outcomes.

That finding does not mean breathing practice is useless. Equally, improvement within both groups does not establish how much was caused by the practices themselves.

It reminds us to distinguish a plausible physiological mechanism from a demonstrated clinical benefit.

Feeling better after practice, changing a physiological measure during practice and developing greater capacity in everyday life are different outcomes.

All may matter. One does not automatically prove the others.

Respiratory interoception: what does your breathing mean to you?

There is another part of this discussion that I think deserves more attention: respiratory interoception.

This concerns how we sense, interpret and evaluate signals associated with breathing. Detecting a sensation, accurately judging it and feeling confident in that judgement are related but distinct processes.

Harrison and colleagues’ research on breathing and anxiety found relationships across several levels of interoceptive processing, including perception, expectations and metacognition: how people evaluate their own perceptions.

For practitioners, the implication is that measuring breathing mechanics alone will not explain someone’s experience.

Consider two people with a strong urge to breathe.

One recognises the sensation from exercise and feels confident that it will settle. The other interprets it as a sign that something is wrong and becomes increasingly alarmed.

That is an illustration of why context and interpretation matter, not a diagnosis of either person.

It also does not mean that unexplained breathlessness is “just anxiety”. Physical causes still require appropriate assessment.

We need to understand both the physiology and the person’s relationship with the sensation.

I explore this relationship further in Respiratory Interoception: The Sensation, Not the Signal.

Why breathing practices need to be individualised

If a breathing exercise is intended to help someone regulate, I want to know more than whether they can follow the instructions.

What are they experiencing? What do they think those sensations mean? Does focusing on breathing help them engage, or does it increase monitoring and worry? What happens when they return to the situation they actually find difficult?

Those questions affect the choice of practice.

For one person, gentle breathing and relaxation may be a useful starting point. For another, movement, external attention or a different approach may be more appropriate.

Where exposure to respiratory sensations is suitable, it needs a clear purpose, appropriate screening and an intensity the person can work with. Greater discomfort is not automatically greater progress.

New, severe or unexplained breathlessness needs medical assessment rather than being assumed to reflect poor regulation.

This broader approach is also why I have argued that functional breathing needs to be understood beyond breathing mechanics.

A breathing pattern has to be interpreted in relation to the person, the task and the circumstances.

From short-term calm to practical capacity

These distinctions inform the practitioner frameworks we teach at School of Breath Science.

In Breath Resilience Instructor Training, the 3R framework brings together Restoration, Regulation and Resilience.

The Breath Science Practitioner Certification develops this reasoning further, including the role of reappraisal within the 4R framework.

These are educational frameworks for organising assessment and practice. They should not be confused with independently validated clinical treatments.

The purpose is to help practitioners consider what a person needs, why a practice might be useful and whether it is helping beyond the session itself.

Can they communicate more effectively? Return to a demanding task? Recover after a stressful event? Participate in something they previously avoided?

Those are meaningful questions alongside changes in symptoms and physiology.

We do not need to feel calm all the time

When I get on stage to speak or teach, I want energy.

I want enough activation to engage with the room, respond to people and communicate with some vitality.

Too much, and I may become distracted by myself or lose flexibility in how I respond. Too little, and I may struggle to bring the presence the situation requires.

The appropriate level is not a fixed number. It depends on the person, the task, their experience and what that moment demands.

That is the shift I would like us to make in how we discuss nervous system regulation.

Calm has its place. So do excitement, effort and the mobilisation of energy.

The aim is to help people develop more choice in how they respond, including the ability to settle when that is useful and stay engaged with activation when life requires it.

For me, that is a more useful goal than trying to feel relaxed all the time.