Understanding Polyvagal Theory: The Science of Safety in Adelaide

Author: Rohan Smith | Functional Medicine Practitioner | Adelaide, SA

For many Adelaide residents struggling with chronic anxiety, brain fog, or persistent fatigue, the issue may not be a lack of motivation or resilience, but a nervous system operating in a prolonged defensive state. Developed by Dr. Stephen Porges, Polyvagal Theory is a neurophysiological framework that seeks to explain how the autonomic nervous system prioritises safety and survival through the vagus nerve. At Elemental Health and Nutrition, this framework is integrated with functional medicine principles to help patients better understand patterns of stress, regulation, and recovery.

Quick Answer: What Is Polyvagal Theory?

Polyvagal Theory proposes that the autonomic nervous system (ANS) responds to perceived safety and threat through three hierarchical states rather than a simple “fight-or-flight versus rest-and-digest” model (1,2). Central to this theory is the ventral vagal complex, sometimes referred to as the social engagement system, which supports calm states, connection, and physiological regulation (3). When safety is not perceived, the nervous system may shift toward sympathetic mobilisation or, in more extreme circumstances, dorsal vagal immobilisation, a pattern described as neuroception-driven rather than consciously chosen (4,15).

The Evolutionary Hierarchy of the Autonomic Nervous System

Polyvagal Theory suggests that autonomic responses follow an evolutionary hierarchy based on neural development.

Ventral Vagal State (Safety and Social Engagement)

This is the most recently evolved autonomic pathway and is unique to mammals. It is associated with calm alertness, social engagement, vocal tone, facial expression, and efficient energy utilisation. States of ventral vagal dominance are associated with physiological conditions that support cellular repair and metabolic efficiency (1,3).

Sympathetic State (Mobilisation)

The sympathetic nervous system supports mobilisation through increased heart rate, cortisol, and adrenaline. While essential for acute stress, chronic sympathetic activation has been associated with dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis and persistent stress physiology (5,6).

Dorsal Vagal State (Immobilisation)

The dorsal vagal pathway is evolutionarily older and is associated with immobilisation responses such as shutdown, dissociation, or fainting when threat is perceived as overwhelming or inescapable. Patterns consistent with prolonged dorsal vagal dominance have been proposed as a contributing factor in some presentations of chronic fatigue syndromes, though this relationship remains theoretical and multifactorial (4,11).

Neuroception: The Body’s Subconscious Safety Scanner

Neuroception refers to the nervous system’s subconscious assessment of safety and danger, occurring independently of conscious thought (1,7). In individuals with a history of trauma, chronic illness, or environmental stressors, neuroception may become biased toward threat detection. This can result in ongoing sympathetic activation even in objectively safe environments, contributing to symptoms such as anxiety, hypervigilance, and fatigue (8,12). Broader discussions of nervous system regulation and mental health often intersect with this concept.

The Vagus Nerve and the Cholinergic Anti-inflammatory Pathway

Beyond its role in autonomic regulation, the vagus nerve is involved in immune signalling through the cholinergic anti-inflammatory pathway. This reflex involves vagal signalling that modulates cytokine production via acetylcholine release, influencing systemic inflammatory activity (9,10).

From a functional medicine perspective, this pathway may be relevant for individuals experiencing chronic inflammatory conditions, including autoimmune presentations (10,13), inflammation associated with environmental exposures such as mould (12,14), and digestive disorders involving the gut–brain axis (11,15). These relationships are associative and form part of an emerging area of research rather than established treatment protocols.

Supporting Vagal Function: A Functional Medicine Perspective

In clinical practice, approaches aimed at supporting autonomic balance focus on reducing threat perception and improving physiological flexibility rather than directly “treating” the vagus nerve.

Nutritional Cofactors

Certain nutrients, including B-vitamins, acetyl-L-carnitine, and choline-containing compounds, are involved in neurotransmitter synthesis and mitochondrial metabolism. These nutrients may support biochemical pathways relevant to acetylcholine production, though their effects on vagal function are indirect and context-dependent (7,12).

Breathing and Movement

Slow diaphragmatic breathing, gentle movement, and posture-based practices have been associated with shifts in autonomic tone and heart rate variability. These practices are commonly used to encourage parasympathetic engagement and bodily awareness (11,13).

Cold Exposure

Brief cold exposure has been studied as an acute autonomic stimulus capable of influencing heart rate variability and sympathetic–parasympathetic balance. Responses vary between individuals, and this approach is not appropriate for all clinical contexts (14,15).

Frequently Asked Questions

Can Polyvagal Theory Help Explain Chronic Fatigue?

Polyvagal Theory has been proposed as one framework for understanding autonomic patterns observed in some people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). These associations are theoretical and do not imply a singular cause or treatment pathway (4,11).

What Is Vagal Tone?

Vagal tone refers to the activity of vagal pathways as reflected in physiological markers such as heart rate variability. Higher vagal tone is associated with improved stress recovery, emotional regulation, and adaptive flexibility (2,9).

Does Diet Affect the Vagus Nerve?

The vagus nerve serves as a primary communication pathway between the gut and brain. Diet-induced gut inflammation may influence vagal signalling, potentially affecting stress perception and autonomic balance (11,14).

Key Insights

• Polyvagal Theory describes three hierarchical autonomic states related to safety and threat perception (1,3).
• Neuroception operates below conscious awareness and influences stress responses (1,7).
• The vagus nerve plays a role in immune modulation through the cholinergic anti-inflammatory pathway (9,10).
• Nervous system regulation involves both neurological and biochemical factors and varies between individuals (12,15).

Rebalancing Nervous System Regulation

If persistent stress or fatigue is affecting your quality of life, understanding your nervous system responses may provide valuable insight. At Elemental Health and Nutrition, assessments are designed to explore physiological contributors to autonomic imbalance and resilience. Consultations are educational and supportive, tailored to individual clinical contexts.