The Vagus Nerve

The vagus nerve is the one piece of anatomy that lies at the heart of somatic therapy and our understanding of the nervous system. Understanding the vagus nerve can genuinely change how you understand your own body, your own responses, and what becomes possible when we work with it deliberately and with care.

The vagus nerve is the longest and most complex of the twelve cranial nerves. It’s name comes from the Latin word for wandering. Beginning in the brainstem, it travels down through the neck, throat, and chest, branching through the heart and lungs, and continuing all the way into the abdomen. It connects the brain to the heart, the lungs, the digestive system, the immune system, and many of the organs essential to life.

It is the primary pathway of the parasympathetic nervous system, the rest and digest system, and carries information in both directions. Approximately 80% of the vagus nerve's fibres are afferent, meaning they carry information from the body up to the brain rather than from the brain down to the body. This is important because it means that working with the body directly is one of the most powerful ways available to us to influence brain function, emotional regulation, and nervous system state. The body is constantly sending information upward to the brain, messages from the gut, the heart, and the viscera are in continuous conversation with the brain.

The Vagus Nerve and Polyvagal Theory

Our modern understanding of the vagus nerve was transformed by the work of neuroscientist Stephen Porges, whose Polyvagal Theory (first published in 1994 and developed extensively since) revealed that the vagus nerve is not a single pathway but a complex, hierarchical system with two distinct branches, each associated with different physiological and psychological states.

The ventral vagal branch is associated with the social engagement system. When this branch is active, we feel safe, connected, and regulated. Our heart rate is steady, our breath is full, our face is expressive, our voice is warm and melodic, and we are able to engage with others and with our environment from a place of genuine ease. This is the state in which healing, digestion, immune function, creativity, and genuine rest are all possible.

The dorsal vagal branch which is the more ancient and primitive pathway, is associated with shutdown, collapse, and freeze. When this branch is activated in response to overwhelming threat, the body powers down, conserving energy, reducing heart rate and breath, and creating the numbness and disconnection of the freeze response.

Between these two vagal states sits the sympathetic nervous system, the fight or flight mobilisation response. Porges' key insight was that these three systems form a hierarchy, and that the nervous system moves through them in a predictable sequence in response to perceived safety or threat. Understanding this hierarchy is foundational to understanding trauma, burnout, anxiety, and the physiological basis of healing.

Polyvagal Theory offers a powerful framework for understanding how our nervous system responds to stress, safety, and connection. It expands our view beyond the traditional “fight or flight” response, showing that our body’s reactions are much more nuanced and deeply rooted in survival and social behavior.

Understanding the vagus nerve

What it is, what it does, and why it matters

Vagal Tone

Vagal tone refers to the activity level of the vagus nerve, the degree to which the ventral vagal pathway is active and the parasympathetic system is engaged. High vagal tone is associated with better emotional regulation, greater resilience to stress, improved cardiovascular health, better digestion, stronger immune function, and greater capacity for social connection and engagement. Low vagal tone is associated with anxiety, depression, chronic inflammation, digestive problems, difficulty recovering from stress, and the kind of persistent nervous system dysregulation that characterises burnout and trauma.

Vagal tone is not fixed, and it can be deliberately, consistently improved through specific practices that stimulate the vagus nerve directly. This is the foundation of somatic therapy, yoga therapy, and the slow medicine approach.

How the Vagus Nerve Connects to Trauma and Burnout

Trauma and chronic stress have a direct and measurable impact on vagal tone and vagus nerve function. When the nervous system has been stuck in sympathetic fight or flight, or collapsed into dorsal vagal shutdown, the ventral vagal pathway loses tone. The social engagement system goes offline. The capacity for genuine rest, connection, and regulation is reduced.

This is why trauma and burnout can feel so physically embodied, showing up as chronic tension, shallow breathing, digestive disturbances, heart palpitations, immune dysregulation, and the sense of being unable to fully relax. The vagus nerve is carrying the imprint of what the nervous system has been through and that imprint needs to be addressed at the physiological level rather than with cognitive understanding.

This is also why somatic therapy and yoga therapy work where talk therapy alone sometimes cannot. By working directly with the body we stimulate the vagus nerve through its own pathways, gradually rebuilding vagal tone and restoring the ventral vagal system's capacity for regulation, safety, and ease.

The Vagus Nerve and the Gut

One of the key aspects of vagus nerve function is its relationship to the gut. The vagus nerve is the primary communication pathway of the gut-brain axis, the conversation between the enteric nervous system in the digestive tract and the central nervous system in the brain.

The gut contains over 100 million nerve cells and produces approximately 95% of the body's serotonin. It’s communication with the brain is via the vagus nerve, continually sending information upward about the state of the digestive system, the microbiome, and the internal environment of the body. When vagal tone is low and the nervous system is in chronic activation, the communication is disrupted, contributing to digestive symptoms like bloating, IBS, and gut dysregulation which commonly accompany anxiety, trauma, and burnout.

Supporting vagal tone through somatic and yoga therapy practices supports not just the nervous system but the gut, and vice versa. This is why breathwork, gentle movement, and nervous system regulation so consistently improve digestive symptoms alongside their effects on anxiety and stress.

The Vagus Nerve and Perimenopause

The vagus nerve is also deeply relevant to the experience of perimenopause.

Oestrogen plays a significant role in vagal tone and vagus nerve function. As oestrogen levels decline during perimenopause, vagal tone can decrease, contributing to the increased anxiety, heart palpitations, sleep disruption, digestive changes, and difficulty regulating the stress response that many perimenopausal women experience. The hot flush itself involves a dysfunction of the thermoregulatory system that is mediated in part through the autonomic nervous system and vagal pathways.

Once again, practices which support vagal tone like breath, movement, sound, somatic regulation are addressing one of the physiological mechanisms through which hormonal decline affects the nervous system and the body.

How Somatic Therapy and Yoga Therapy Work With the Vagus Nerve

Every somatic therapy and yoga therapy practice I offer works with the vagus nerve. Understanding the mechanisms helps explain why these practices are not merely relaxing but genuinely therapeutic.

Breath practices - The exhale phase of breathing directly stimulates the vagus nerve through its branches in the diaphragm and lungs. Extended exhale breathing, which makes the exhale longer than the inhale, is one of the most evidence-supported tools available for increasing vagal tone and shifting the nervous system toward parasympathetic regulation. Diaphragmatic breathing creates a gentle pumping action through the abdominal cavity that massages the vagal branches running through the gut, further supporting the gut-brain connection.

Bhramari pranayama - humming bee breath Humming creates vibration in the throat and larynx that directly stimulates the vagal branches running through these structures producing measurable increases in vagal tone and parasympathetic activation. Research has shown that humming increases nitric oxide production in the sinuses, supports vasodilation, and has immediate and measurable effects on heart rate variability, one of the primary markers of vagal tone.

Somatic movement like shaking and rocking - Gentle shaking and rhythmic rocking stimulate the vestibular system, which has direct connections to the vagal pathways governing autonomic regulation. Rhythmic movement creates a sense of predictability and safety that the nervous system finds deeply regulating, and the bilateral stimulation of rocking supports the integration of left and right brain hemispheres, further supporting vagal tone and emotional regulation.

Yoga nidra and restorative yoga - Extended rest practices that bring the nervous system into deep parasympathetic states like yoga nidra and restorative yoga, allow the ventral vagal system to consolidate and strengthen. The body in supported, effortless rest is the body building vagal tone through the sustained experience of genuine safety and ease.

Orienting - deliberate practice of looking slowly around the environment as if seeing it for the first time, activates the social engagement system through the vagal connections to the eye muscles and visual processing pathways. Orienting is such an immediately effective nervous system regulation tool because it speaks directly to the vagus nerve's role in assessing environmental safety.

Why This Matters

Understanding the vagus nerve changes what healing looks like.

It means that lying on the floor and humming is not self-indulgence, it is a direct physiological intervention with the nervous system. That gentle rocking is not a trivial comfort but a vestibular-vagal regulation practice with measurable effects on autonomic function. The quality of the breath matters and every slow exhale is a genuine act of nervous system support.

We are an active participant in our body’s healing and regulation. By working with the breath, the voice, movement, and the felt sense of the body, we are working directly with the neural pathways that govern our capacity for safety, regulation, and ease.

And it means that slow medicine is not just a philosophy. It is a physiology.

References

Porges, S. W. (2011). The polyvagal theory: Neurophysiological foundations of emotions, attachment, communication, and self-regulation. W. W. Norton.

Breit, S., Kupferberg, A., Rogler, G., & Hasler, G. (2018). Vagus nerve as modulator of the brain-gut axis in psychiatric and inflammatory disorders. Frontiers in Psychiatry, 9, 44. https://doi.org/10.3389/fpsyt.2018.00044

Gerritsen, R. J. S., & Band, G. P. H. (2018). Breath of life: The respiratory vagal stimulation model of contemplative activity. Frontiers in Human Neuroscience, 12, 397. https://doi.org/10.3389/fnhum.2018.00397