Breathing as a Regulator of the Autonomic System

Series: Breathing, Body, Consciousness, and the Shifting of the Tensional Selves (Eus Tensionais)

Introduction — Brain Bee (first-person consciousness)

As I pay attention right now, I notice something simple:
I’m not breathing the same way all the time.

There are moments when air rushes in quickly, as if there’s barely any space.
At other times, the exhale lengthens and the body seems to loosen from the inside.

Nothing changed around me—but I changed.
My body didn’t ask my mind for permission.
It simply adjusted the rhythm to keep functioning.

Before any technical explanation, this is what I can feel:
to breathe is to regulate.

The autonomic system doesn’t choose sides—it alternates

People often talk about the autonomic system as if it had two opposite “modes”:

• sympathetic (action),

• parasympathetic (rest).

But that opposition is didactic, not biological.
In real life, a healthy body continuously oscillates between these poles.

The sympathetic branch is not an enemy.
The parasympathetic branch is not a reward.
What keeps the system functional is the capacity to transition.
And breathing is the main axis of that transition.

Breathing: the only direct gateway to the autonomic system

Unlike other autonomic processes, breathing holds a singular place:
it happens automatically,
but it can also be perceived and modulated.

Each breathing cycle alters, in real time:

• vagal tone,

• heart rate,

• beat-to-beat variability,

• muscular and visceral organization.

That’s why talking about breathing is not talking about “technique.”
It’s talking about coordination between systems.

Inhalation, exhalation, and the vagus nerve

During inhalation:

• the vagal “brake” is momentarily reduced,

• heart rate tends to rise.

During exhalation:

• the vagus nerve reasserts its influence,

• heart rate tends to fall.

This phenomenon—known as respiratory sinus arrhythmia—is not an error.
It is a sign of health.

When this oscillation disappears, the body loses regulatory finesse.

One breathing pattern, different Selves

Here a central point of the series comes in.
There is no single “correct” way to breathe.
What exists are breathing patterns that are functional for different tensional selves.

Within the same baseline respiratory physiology, these can coexist:

• a Self of readiness,

• a Self of attention,

• a defensive Self,

• a Self of fruition.

What changes is not only the air that enters,
but how the body uses that air:
where it holds tension,
where it allows release,
how it distributes energy.

Breathing sustains the Self—
and the Self shapes breathing.

When breathing loses variability

Under prolonged stress, rigid belief, or continuous demand, breathing tends to:

• shorten,

• lose pauses,

• become excessively controlled or contained.

This is not a moral or psychological failure.
It is adaptation.

The problem arises when this adaptation has no exit.
The sympathetic branch remains dominant,
the vagus nerve loses room,
and the ability to shift between Selves decreases.

At that point, it’s not the mind that is “stuck.”
It’s the body that lost its margin to vary.

Breathing doesn’t choose the Self—it enables the shift

A common mistake is to use breathing to “change state” by force.
That often fails.

The role of breathing is not to impose a Self,
but to open space so another Self can emerge.

When breathing regains variability:

• RMSSD tends to rise,

• the body gains room for adjustment,

• consciousness expands,

• the Tensional Self loses rigidity.

None of this is symbolic.
It is physiological.

Normality, not correction

Breathing fast during action is normal.
Breathing contained during alertness is normal.
Breathing loose in safety is normal.

The criterion is not the type of breathing,
but the possibility of transition.

When the body can go and come back, it is healthy.
When it gets stuck, it suffers.

Recognizing this in your own body

No technique, no prescription.
Just observing:

• Can my breathing change spontaneously?

• Can I perceive the difference between inhaling and exhaling?

• Can I exit tension without collapsing?

• Can I tense without losing myself?

These questions regulate more than any exercise.

Closing

Breathing is not calming or stimulating by nature.
It is organizing.

It coordinates the vagus nerve, sympathetic, and parasympathetic activity
so the body can alternate states without breaking.

This alternation sustains life,
consciousness,
and the healthy shifting of the tensional selves.

This text is part of the series Breathing, Body, Consciousness, and the Shifting of the Tensional Selves (Eus Tensionais), where different aspects of the same living system are approached from complementary angles.

References (post-2020)

Thayer, J. F., & Lane, R. D. (2021). A Model of Neurovisceral Integration in Emotion Regulation. Biological Psychology.
→ Grounds the functional integration between breathing, heart, and brain as the basis of autonomic regulation.

Laborde, S., Mosley, E., & Thayer, J. F. (2022). Heart Rate Variability and Cardiac Vagal Tone in Psychophysiological Research. Biological Psychology.
→ Presents RMSSD as a sensitive marker of vagal tone associated with physiological flexibility.

Kim, H. G., et al. (2021). Respiration–Heart Rate Coupling and Autonomic Regulation. Frontiers in Neuroscience.
→ Demonstrates how breathing directly organizes cardiac and autonomic dynamics.

von Rosenberg, W., et al. (2020). Respiratory Influences on Heart Rate Variability. IEEE Reviews in Biomedical Engineering.
→ Analyzes the effects of different breathing patterns on HRV in real-world contexts.

Shaffer, F., Meehan, Z. M., & Zerr, C. L. (2020). A Critical Review of HRV Norms and Interpretation. Frontiers in Neuroscience.
→ Reinforces contextual interpretation of HRV, aligned with the idea of dynamic normality.

Forte, G., et al. (2022). Heart Rate Variability and Interoceptive Awareness. Neuroscience & Biobehavioral Reviews.
→ Links respiratory regulation, HRV, and conscious bodily perception.

Lehrer, P. M., et al. (2020). Heart Rate Variability Biofeedback: How and Why Does It Work? Frontiers in Psychology.
→ Highlights breathing as a direct pathway for modulating the autonomic system.

Park, G., et al. (2021). Respiration Shapes Neural Activity and Cardiac Function. Journal of Neuroscience.
→ Shows how respiratory cycles simultaneously modulate neural and cardiac activity.