Something Nobody Told Us
I remember the first time I came across the term vagal tone. I was deep in a research spiral, several weeks into trying to understand why my nervous system felt so chronically switched on, why rest never quite felt like rest, why I could do everything right on paper and still wake up with that low hum of tension already present before the day had even made its demands.
Vagal tone. Two words I had never heard in any conversation about wellbeing, in any fitness class, in any of the wellness content I had been consuming for years. And yet the more I read, the more I realised it was the missing piece. The thing beneath all the other things. The reason some people seem to return to calm naturally, and others, despite their best efforts, keep finding themselves back at the starting line.
If you have read about the parasympathetic nervous system in The Still Room before, you will know that it is the body’s rest-and-restore state, the counterpart to the fight-or-flight system that most of us spend far too much time living inside. What I want to explore in this blog is the specific structure that governs the parasympathetic state, how it works, what it means when it is undertrained, and how to build its strength over time deliberately.
That structure is the vagus nerve. And once you understand it, the way you approach calm changes completely.
What the Vagus Nerve Actually Is
The vagus nerve is the longest cranial nerve in the human body. It originates in the brainstem and travels downward through the neck, chest and abdomen, branching out to reach the heart, the lungs, the diaphragm and the digestive tract. Its name comes from the Latin word for wandering, which is precisely what it does, moving through more of the body than any other nerve in the system.
It is the primary pathway of the parasympathetic nervous system. Approximately 80% of the fibres in the vagus nerve are afferent, meaning they carry information upward from the body’s organs to the brain rather than downward. This is a profoundly important detail. It means that the majority of what the vagus nerve does is listen. It listens to the heart. It listens to the gut. It listens to the lungs. And it carries what it hears directly to the brainstem, where the information shapes how the brain interprets the body’s safety, its readiness to rest, its capacity to regulate.
The vagus nerve governs heart rate, respiratory rate, digestive function and the body’s inflammatory response. It is involved in the production of acetylcholine, one of the nervous system’s most important calming neurotransmitters. It connects the brain to the gut through what researchers now call the gut-brain axis, a bidirectional communication pathway that is increasingly understood to influence mood, anxiety, cognitive clarity and immune function.
In short, the vagus nerve is not a minor anatomical structure. It is one of the most important regulatory systems in the entire body.
Vagal Tone: The Measure That Matters
Here is the concept that changed how I think about my own nervous system health.
Vagal tone refers to the activity level of the vagus nerve, specifically its resting baseline of parasympathetic influence over the body’s organs. Think of it like the fitness of a muscle. A muscle that is never trained becomes weak and slow to respond. A muscle that is consistently and progressively trained becomes stronger, more responsive and more resilient under pressure. The vagus nerve works in exactly the same way.
High vagal tone is associated with a remarkable range of health outcomes. Research consistently links it to better emotional regulation, greater resilience under stress, improved cognitive function, healthier digestion, lower levels of systemic inflammation and more flexible, adaptive cardiovascular function. High vagal tone is also associated with what researchers call a positive feedback loop, where greater emotional wellbeing reinforces vagal activity, which in turn supports further emotional wellbeing. The nervous system, it turns out, rewards its own training.
The most accessible measurement of vagal tone is heart rate variability, often abbreviated as HRV. This is the variation in time between successive heartbeats, and it is one of the most sensitive indicators of autonomic nervous system health available. A heart that beats with rigid, clock-like regularity is actually less healthy than one that shows natural, responsive variation between beats. That variation is the vagus nerve’s signature. The more expressive and variable the heart rate at rest, the stronger the vagal tone and the more capable the parasympathetic nervous system is of doing its work.
Why So Many of Us Have Undertrained Vagal Tone
The chronic stress of modern life does something specific to the vagus nerve. It does not damage it, exactly. It simply suppresses it, consistently and over time, through the constant dominance of the sympathetic nervous system.
When the body is in fight or flight, when cortisol is elevated, and when the nervous system is braced against the next demand, the vagus nerve’s influence is overridden. Temporarily, this is functional. The body should suppress rest and restore when it genuinely needs to respond to a threat. The problem is that modern life provides a near-continuous stream of perceived threats, notifications, deadlines, difficult conversations, overstimulation and information overload, without the genuine resolution that the nervous system evolved to expect after a threat had passed.
The result is a vagus nerve that is chronically underused, chronically overridden and never given enough consistent space to exert its calming influence. Vagal tone drops. The nervous system loses flexibility. The capacity to shift from activated to restored becomes slower and less reliable. Rest begins to feel effortful rather than natural. Sleep is shallow. Digestion is compromised. Anxiety sits closer to the surface than it should.
I recognise this pattern deeply from my own experience. Years of extending outward, of absorbing and continuing and holding things together, without understanding that the nervous system was keeping a quiet and cumulative account.
How to Train the Vagus Nerve
This is where the science becomes practical and, honestly, hopeful.
Vagal tone can be improved. Deliberately, measurably and through practices that are accessible, non-pharmaceutical and entirely within reach. The vagus nerve responds to training the same way the body responds to physical practice, through consistent, repeated inputs that build its strength and responsiveness over time.
Slow, extended breathing is the most consistently evidenced vagal stimulus available. When we exhale for longer than we inhale, the vagus nerve releases acetylcholine into the heart, slowing the heart rate and signalling the parasympathetic system to activate. Research has identified a breathing rate of approximately six breaths per minute, roughly a five-second inhale followed by a five-second exhale, as optimal for improving heart rate variability and vagal tone. Even a few minutes of this each day, practised consistently, builds measurable change over time.
Humming, chanting and singing stimulate the vagus nerve through vibration. The nerve passes through the throat and is directly connected to the muscles of the larynx and vocal cords. When these muscles vibrate through sustained sound, the vagus nerve is activated. Research has found that humming produces some of the highest measures of parasympathetic activity of any simple practice studied, with one study finding the stress index during sustained humming lower even than during sleep.
Cold water exposure activates the mammalian diving reflex, a hardwired physiological response that slows the heart rate and stimulates the vagus nerve. Even splashing cold water on the face or the back of the neck produces a measurable parasympathetic response. Consistent cold exposure over time has been shown to reduce sympathetic baseline activity and improve vagal tone.
Yoga and mindful movement, particularly practices that incorporate slow breath-linked movement and inversions, consistently stimulate vagal pathways. The research on yoga and the autonomic nervous system is extensive and robust. A single yoga session measurably increases GABA levels, the brain’s primary inhibitory neurotransmitter, while regular practice builds lasting changes in parasympathetic baseline. If you want to explore the specific practices most supported by science, the Ahloki yoga poster collection was built precisely around this understanding.
Ritual and sensory practice also play a role that is often underestimated. The vagus nerve is exquisitely sensitive to the signals the brain uses to assess safety. When an environment consistently and repeatedly signals safety through familiar sensory cues, familiar scents, familiar rhythms, familiar objects, the vagus nerve’s suppression is lifted a little more each time. This is the neuroscience beneath the Ahloki approach to scent and ritual, explored in depth in our blog on what actually happens in the brain when you smell something.
The Training Principle
What I find most compelling about the vagus nerve is not any single intervention. It is the principle that underlies all of them.
The vagus nerve responds to repetition. It builds tone through consistent practice, the way muscles build strength, the way the basal ganglia builds habit. No single breath, no single session, no single evening ritual transforms vagal tone overnight. But a nervous system that is given consistent, repeated, sensory signals of safety over weeks and months begins to shift its baseline. The parasympathetic state becomes more accessible. The return to calm after activation becomes faster. The body begins to trust, at a physiological level, that rest is available.
This is not a passive process. It is a practice. And like all practices worth building, it is the consistency that creates the change rather than the intensity of any single moment.
The vagus nerve is not broken in most of us. It is simply undertrained. And undertrained things, given the right conditions and enough consistent attention, respond.
That is perhaps the most useful thing I have come to understand about the nervous system. It is not fixed. It is always learning. And what it learns depends entirely on what we choose to repeat.
The Ahloki ritual collection was built around the practices the nervous system actually responds to. Explore The Still Room for more on the science of calm, scent and intentional living.
