There is a nerve in your body that most people have never heard of, yet neuroscientists increasingly describe it as one of the most important regulators of physical and mental health we have. It connects your brain to nearly every major organ in your body. It is a central player in how you handle stress, emotion, inflammation, digestion, sleep, and social connection. And unlike most of the nervous system, you have meaningful influence over how it functions.

This is the vagus nerve. And understanding it may change how you think about recovery, regulation, and what the body needs after hard times.

What the Vagus Nerve Is

The vagus nerve — from the Latin for “wandering” — is the longest cranial nerve in the body. It originates in the brainstem and travels down through the neck, chest, and abdomen, branching out to communicate with the heart, lungs, gut, liver, spleen, kidneys, and other organs. Unlike most nerves that run in one direction, about 80 percent of the vagus nerve’s fibres carry information upward — from the body to the brain — rather than downward. This makes it a critical communication highway, constantly reporting on the state of your internal world.

The vagus nerve is the primary component of the parasympathetic nervous system — the branch responsible for rest, digestion, repair, and recovery. When the vagus nerve is functioning well, it acts as a powerful brake on the stress response, helping the body return to calm after activation. When it is underactive, the stress response can run on long after the threat has passed.

Polyvagal Theory: A New Understanding

In 1994, neuroscientist Stephen Porges proposed a framework he called polyvagal theory, which offered a richer account of how the vagus nerve influences human behaviour and wellbeing. Rather than a simple on/off stress response, Porges described a hierarchy of three states, each governed by a different part of the nervous system.

The ventral vagal state — associated with the newer, myelinated portion of the vagus nerve — is the state of safety, social engagement, and connection. In this state, the heart rate is regulated, the face is expressive and receptive, the voice is warm and prosodic, and the body is capable of rest, play, creativity, and intimacy. This is the optimal state for both wellbeing and complex thinking.

Below this, the sympathetic state is the mobilised survival response — fight or flight — associated with perceived threat. And below that, the dorsal vagal state is the oldest branch of the nervous system, responsible for the freeze or shutdown response when threat is overwhelming.

This framework has transformed how many therapists, researchers, and clinicians understand trauma, anxiety, depression, chronic illness, and the biology of human connection.

Vagal Tone: What It Is and Why It Matters

Vagal tone refers to the activity level of the vagus nerve — essentially, how well it is doing its job of keeping the parasympathetic system engaged and the stress response appropriately calibrated. High vagal tone is associated with better emotional regulation, stronger immune function, lower levels of inflammation, more positive social relationships, greater resilience in the face of stress, and lower rates of anxiety and depression.

Low vagal tone, by contrast, is associated with difficulty recovering from stress, greater susceptibility to inflammation and autoimmune conditions, poorer emotional regulation, heightened anxiety, and a reduced sense of connection with others.

Vagal tone is commonly measured using heart rate variability (HRV) — the natural variation in the intervals between heartbeats. A healthy heart does not beat with metronomic regularity. It subtly speeds up during inhalation and slows during exhalation. This variation reflects the vagus nerve doing its job. Higher HRV generally indicates higher vagal tone and greater resilience.

Signs That Your Vagal Tone May Be Low

  • Difficulty recovering from stressful situations — you stay activated long after the event
  • Digestive problems, including irritable bowel, nausea, or slow digestion
  • Frequent colds or infections (the vagus regulates immune function)
  • Chronic inflammation or autoimmune flare-ups
  • Difficulty feeling present in social situations
  • Anxiety that feels constant rather than situational
  • A flat or monotone voice (the vagus controls the muscles of the face and larynx)
  • Difficulty swallowing or a frequent need to clear your throat
  • Feeling emotionally numb or shut down

The Connection Between the Gut and the Brain

One of the most significant and surprising findings in vagus nerve research is the extent of its role in the gut-brain connection. The enteric nervous system — sometimes called the second brain — lines the entire digestive tract and contains more neurons than the spinal cord. The vagus nerve is the primary communication channel between the gut and the brain.

This means that gut health directly influences mental health, and vice versa. The chronic digestive symptoms that so often accompany anxiety and trauma are not coincidental. They are part of the same dysregulated system. And practices that improve vagal tone — including certain dietary approaches, probiotic support, and breathwork — can produce measurable improvements in both gut health and mood.

The Good News: Vagal Tone Can Be Improved

Unlike many aspects of health, vagal tone responds well to deliberate intervention. A growing body of research has identified specific, accessible practices that increase vagal activity, improve HRV, and shift the nervous system toward the ventral vagal state of safety and connection.

These include slow, rhythmic breathing with an extended exhale; humming, singing, or chanting (which directly vibrate the vagus nerve via its connections to the larynx); cold water exposure on the face or neck; regular gentle exercise; meditation and mindfulness; and — crucially — safe, warm social connection. Each of these activates the vagus in different ways, and their combined effect over time is measurable and meaningful.

This is one of the most hopeful findings in contemporary neuroscience: the body’s stress-regulation system is not fixed at birth or set irrevocably by early experience. It is malleable. With the right inputs, the vagus nerve becomes better at doing its job — and life, in consequence, becomes more navigable.

Why This Matters for Life Transitions

Major life changes — grief, divorce, job loss, illness, relocation — place the nervous system under sustained load. The vagus nerve, already doing its best to keep the system balanced, comes under greater strain. Understanding this is not just intellectually interesting. It is practically important.

It means that recovery from hard things is not purely a psychological or emotional process. It is also a physiological one. And tending to the vagus nerve — through breath, movement, safe relationship, and deliberate practice — is not self-indulgence. It is one of the most evidence-based things a person navigating transition can do.

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