Day 6

Understanding the Vagus Nerve and Polyvagal Theory

Pathways to Safety Within the Body

The vagus nerve is your body's primary stress recovery system, influencing heart rate, digestion, inflammation, and emotional states. Polyvagal Theory (Porges, 2011) explains how the autonomic nervous system (ANS) adapts to perceived threats or safety, shaping our stress responses, social engagement, and ability to regulate emotions.

The stress response system is developed as early as in utero and continues to develop into early childhood, meaning that our nervous system forms automatic patterns for responding to stress based on our earliest experiences (Loman & Gunnar, 2010). While these patterns are adaptive in childhood, they can persist into adulthood, even when they are no longer necessary or appropriate (Lupien et al., 2009).

Breathwork can rewire this coded stress response, retraining the nervous system to distinguish real vs. perceived threats, improve vagal tone, and create more adaptive, situationally appropriate responses (Lehrer & Gevirtz, 2014).

Today, we’ll explore:

  • How prenatal and early childhood environment shape nervous system development and lifelong stress responses.
  • The vagus nerve’s role in regulating stress and emotional resilience.
  • Polyvagal Theory, explaining how the nervous system shifts between safety, stress, and shutdown.
  • Why early “survival wiring” may no longer be necessary in adulthood, and how breathwork can rewire outdated stress responses.
  • How breathwork stimulates the vagus nerve, restoring nervous system balance and adaptability.
Reading time: 14 mins

The Vagus Nerve: The Body’s Stress-Regulation Superhighway

The vagus nerve (Cranial Nerve X) is the longest nerve in the autonomic nervous system, extending from the brainstem to the heart, lungs, and digestive tract. It is responsible for:

Stress Regulation

Regulating stress responses by controlling heart rate variability (HRV).

Immune Health

Modulating inflammation, playing a crucial role in immune function (Gidron et al., 2018).

Gut-Brain Communication

Supporting digestion, gut-brain communication, and emotional regulation (Breit et al., 2018).

Communication Pathway

Shifting between stress states (SNS/DVC) and recovery states (PNS).

A well-regulated vagus nerve helps us feel safe and connected, while functional dysregulation can contribute to chronic stress, anxiety, and inflammatory conditions (Porges, 2011).

How Stress Responses Are Formed in Early Life

From before birth, the nervous system is shaped by environmental influences, including maternal stress, which can alter fetal brain development and autonomic regulation (Glover, 2011).

This prenatal programming continues postnatally, where early interactions with caregivers further shape stress responses (Loman & Gunnar, 2010). >

Responsive and Safe

When caregiving is responsive and safe, the nervous system learns adaptive stress responses, developing ventral vagal regulation, which enables healthy emotional processing and social engagement.

Dysregulated Stress Responses

If early environments are unpredictable, stressful, or lack safety, the nervous system learns dysregulated stress responses, becoming hypersensitive (SNS dominance) or shutting down (DVC dominance) (Shonkoff et al., 2012).

Chronic Stress Responses

These early patterns persist into adulthood, often triggering outdated survival responses in everyday situations, such as anxiety in social settings, chronic hypervigilance, or emotional shutdown in response to minor stressors (Lupien et al., 2009).

Deeper dive into this on Day 9: The Origins of Stress

Polyvagal Theory: How Old Stress Patterns Show Up In Adulthood

Polyvagal Theory (Porges, 2011) describes how our autonomic nervous system (ANS) responds to stress, safety, and survival needs through three pathways:

State
Function
Physical & Emotional Signs
Ventral Vagal (Safety & Connection)
Social engagement, emotional regulation, adaptability
Calm, connected, creative, clear thinking, digestion optimised
Sympathetic (Fight-or-Flight)
Mobilisation to face or escape a threat
Anxiety, rapid heart rate, muscle tension, hypervigilance
Dorsal Vagal (Freeze/Shutdown)
Immobilisation when overwhelmed or helpless
Numbness, dissociation, chronic fatigue, digestive shutdown

The key to nervous system resilience isn’t eliminating stress—it’s training the system to return to ventral vagal balance quickly and appropriately.

Breathwork as a Tool to Rewire the Coded Stress Response

Just as early experiences shape autonomic patterns, breathwork provides a direct way to retrain these responses. By stimulating the vagus nerve and increasing vagal tone, routine breathwork helps shift outdated stress responses into more proportionate reactions in adulthood (Lehrer & Gevirtz, 2014).

4-8 Breathing

A great exercise for this is Extended Exhalation Breathing, such as 4-8 Breathing, a scientifically supported breathwork technique.

Why it works

Resilience

Extending the exhale increases vagal tone, slowing heart rate, reducing stress hormones (cortisol) and HRV improvement (Lehrer & Gevirtz, 2014).

Oxygen Efficiency

Enhances nitric oxide production, which improves circulation and oxygen delivery (Lundberg et al., 1996).

Reduce Inflammation

Reduces inflammation by activating the anti-inflammatory pathway (Tracey, 2002).

Practicing this daily strengthens the vagus nerve, improving nervous system adaptability.

Day 6 Breathwork

4-8 Breathing

A calming technique that reduces stress and promotes deep relaxation. Inhale through your nose for 4 seconds, then exhale slowly through your mouth for 8 seconds. Maintain a steady, controlled rhythm throughout the exercise.

This breathing method focuses on extending the exhale, which helps activate the parasympathetic nervous system and trigger the body's natural relaxation response. By creating a longer exhale, practitioners can quickly reduce anxiety, lower heart rate, and decrease cortisol levels. The extended breath pattern signals to the brain that you are safe, helping to interrupt stress cycles and promote mental calmness. Regular practice can improve emotional regulation, enhance mindfulness, and provide a portable stress-management tool that can be used in various settings, from workplace tension to pre-sleep relaxation routines.

Regular practice can improve emotional regulation, enhance mindfulness, and provide a portable stress-management tool that can be used in various settings, from workplace tension to pre-sleep relaxation routines.

Comparing Between Previous PNS-Activating Breathwork Techniques

Breathwork Technique
Primary Function
Nervous System Effect
Best Used For
Diaphragmatic Breathing (Day 2)
Expands lung capacity, slows breathing
General PNS activation
Everyday relaxation, improving baseline breathing patterns
Coherent Breathing (Day 4)
Maintains equal inhales & exhales
Balances SNS-PNS, optimises HRV
Heart rate coherence, emotional stability, sleep support
4-8 Breathing (Day 6)
Extends exhalation to stimulate vagus nerve
Strong PNS activation, enhances vagal tone
Shifting out of stress, reducing anxiety, deep relaxation

Which one should you use?

  • If you need general relaxation and to improve vagal tone, Diaphragmatic Breathing is a great place to start.
  • If you're looking to stabilise emotions or improve sleep, Coherent Breathing offers a steady, balanced rhythm.
  • If you're feeling anxious or overwhelmed, 4-8 Breathing is the most effective for downregulating the nervous system.

Key Takeaways

  • The vagus nerve is central to stress recovery, inflammation control, and emotional regulation.
  • Prenatal and early childhood experiences shape lifelong stress responses, which often persist into adulthood.
  • Polyvagal Theory explains how we shift between safety, stress, and shutdown.
  • Breathwork can rewire outdated autonomic patterns, restoring balance and resilience.
  • 4-8 breathing is a proven method to strengthen vagal tone and support long-term well-being.

Coming up

Tomorrow, we shift from theory to practice with Nervous System Mapping: Getting to know your Nervous System. See you tomorrow!