But there’s a second stress system running alongside the sympathetic branch, one that operates on a slower timescale and has longer-lasting effects on virtually every system in the body. It doesn’t fire in seconds. It unfolds over minutes, hours, and in the case of chronic stress, years.

It’s called the HPA axis, and it’s one of the most important and most misunderstood systems in the biology of stress.

What the HPA Axis Actually Is

HPA stands for hypothalamic-pituitary-adrenal, three structures that form a hormonal relay system, each one triggering the next in a cascade.

It begins in the hypothalamus, that small master coordinator we met in the first post, nestled near the base of the brain just above the brainstem. When the hypothalamus perceives a stressor, it initiates the cascade. And it’s worth pausing here on the word perceives, because the hypothalamus does not distinguish between a real threat, an anticipated one, or an imagined one. If you vividly picture a stressful conversation you’re dreading, or replay an argument that happened three days ago, or lie awake catastrophizing about something that may never occur, the hypothalamus can read that as a live threat and trigger the same hormonal chain of events as if the danger were standing right in front of you. The nervous system, in this sense, does not always know the difference between what is happening and what you are thinking about.

From the hypothalamus, a signaling hormone is released that travels to the pituitary gland, a pea-sized structure at the base of the brain, often called the “master gland” for how many hormonal systems it governs. The pituitary responds by releasing its own hormone into the bloodstream, which then travels to the adrenal glands, the two small, triangular glands sitting atop each kidney, signaling them to release cortisol.

The whole cascade, from perception of a stressor to peak cortisol levels, unfolds over roughly 20–30 minutes. Which is why this system is slower than the immediate epinephrine spike of the sympathetic branch, but also why its effects are more sustained and why a stressful morning can still be chemically present in your student’s body when they arrive for an evening class if they’re still reliving that stressor.

Cortisol: Still Not the Villain

We touched on this in the last post, but it bears repeating here with more depth: cortisol is not a stress hormone in the pejorative sense. It is a survival hormone that also happens to be released under stress.

On a normal, unstressed day, cortisol follows a natural rhythm. It actually begins rising before you wake up, and that rising cortisol level is part of what causes you to wake up, providing the physiological readiness to meet the day. It peaks sharply in the first 30-45 minutes after waking, known as the cortisol awakening response, delivering energy, mental clarity, and alertness. It then gradually declines through the afternoon and evening, reaching its lowest point in the early hours of sleep. This rhythm, called the diurnal cortisol curve, is one of the markers clinicians use to assess overall stress system health.

Cortisol does essential work throughout this daily cycle. It regulates blood sugar by signaling the liver to release stored glucose for fuel, the same mechanism that kicks in during a challenging power yoga class or any sustained physical effort, giving your muscles the energy they need to keep going. It modulates immune function. Contrary to popular belief, cortisol doesn’t simply suppress immunity; it regulates it, preventing inflammatory responses from overshooting. It supports cardiovascular function, assists in memory consolidation, and plays a role in mood stability.

The issue, as always, is not the hormone itself. Like most things in the body, too much of it for too long stops being a resource and starts being a liability.

When the Cascade Doesn’t Turn Off

Under healthy conditions, the HPA axis has a built-in off switch. As cortisol rises in the bloodstream, it feeds back to the hypothalamus and pituitary, essentially signaling: message received, you can stand down. This negative feedback loop is what allows the stress response to be time-limited. Stressor arrives, cascade activates, cortisol rises, feedback signals resolution, and the system returns to baseline.

But this elegant mechanism has vulnerabilities.

When stressors are chronic, such as financial pressure, relationship conflict, caregiving demands, systemic inequity, trauma looping, or a nervous system that never fully learned to return to baseline, the feedback loop becomes dysregulated. The hypothalamus keeps signaling. The pituitary keeps responding. The adrenal glands keep producing. And the body stays in a prolonged state of cortisol elevation it was never designed to sustain.

Over time, this does measurable damage across multiple systems:

Sleep deteriorates. Cortisol and melatonin have an inverse relationship; as one rises, the other falls. Chronically elevated evening cortisol is associated with lower melatonin signaling and more fragmented sleep architecture, reducing the deep, restorative stages the nervous system most needs to recover.

Immune function is disrupted. Short-term cortisol elevation is anti-inflammatory. Chronic elevation does the opposite. It desensitizes immune cells to cortisol’s regulatory signal, which paradoxically leads to increased baseline inflammation. This is one of the mechanisms that can connect chronic stress to conditions like autoimmune disorders, cardiovascular disease, and accelerated cellular aging.

Memory and cognition are affected. The hippocampus, the brain region most central to memory formation and threat contextualization, is densely packed with cortisol receptors and highly sensitive to sustained cortisol exposure. Chronic stress can reduce hippocampal volume over time, which matters enormously for a very specific reason. A healthy hippocampus allows the nervous system to accurately assess whether something is actually a threat. It’s the part of the brain that looks at a stick on the ground and says that’s just a stick, after your amygdala, your threat-detection center, has already fired as if it were a snake. When the hippocampus is compromised by chronic stress load, that corrective signal weakens. The amygdala keeps firing. Threat responses become hair-trigger. The nervous system starts to lose its ability to distinguish between real danger and the memory or anticipation of it, which, as we noted earlier, the hypothalamus was never very good at distinguishing in the first place.

Mood dysregulation increases. Chronic HPA-axis disruption shows up frequently in depression research and anxiety-related conditions. The relationship is bidirectional. Stress dysregulates mood, and mood dysregulation sustains stress activation, creating feedback loops that can be genuinely difficult to interrupt through top-down means alone (more on this in a future post).

Over time, the stress response itself can become dysregulated. After sustained periods of high demand, cortisol rhythms may become altered, sometimes showing lower morning output or a flattened daily curve. This can show up as the flat, depleted, can’t-get-going feeling many people describe as burnout. Morning cortisol may fail to peak adequately, energy can feel low, and recovery may be slow. The diurnal rhythm that normally rises in the morning and falls through the day can lose its natural shape.

This cumulative toll is what we referred to in the first post as allostatic load, the physiological cost of sustained, unresolved adaptation. The HPA axis is one of its primary mechanisms.

What This Looks Like in Your Classroom

You cannot look at a student and know their HPA axis history. But you can develop an informed intuition for what chronic stress load looks like in a body.

The student who is perpetually exhausted but can’t relax. The one who moves through a vigorous practice without ever seeming to build heat, a nervous system so habituated to high activation that it barely registers the input. The one who bursts into tears in a hip opener, not because something dramatic happened, but because the body finally found enough safety to release what it had been holding. The one who falls asleep in every savasana, not from peace, but from a nervous system that collapses the moment vigilance is no longer required.

These can be outward patterns of chronic stress physiology. Not diagnoses; you are not your students’ clinician, but patterns worth recognizing and having compassion for.

What yoga offers these students is not a fix. Chronic HPA dysregulation is not resolved by a single class, a single workshop, or even a single year of consistent practice. But a well-held yoga class, one that builds activation and then guides genuine recovery, creates safety through consistency and predictability, and uses breath, movement, stillness, and consent-based touch as bottom-up regulatory tools, is a legitimate input into the system. Over time and with repetition, it can contribute to improving stress regulation, lowering baseline activation, and restoring some of the flexibility the system has lost.

This is not conjecture. There is a growing body of research suggesting that regular yoga practice can influence measurable markers of stress physiology, including cortisol levels, HPA axis reactivity, and inflammatory markers.

The Takeaway

The HPA axis is the body’s slow-burn stress system, powerful, essential, and vulnerable to the demands of modern life in ways the sympathetic nervous system alone doesn’t fully capture. Understanding it gives you a more complete picture of what chronic stress actually does to a human body and why so many of your students arrive carrying far more than their yoga mat.

In the next post, we turn to the other side of the autonomic nervous system, the parasympathetic branch, the vagus nerve, and the biology of genuine rest.

This is the third post in a foundational series on nervous system literacy for yoga teachers. Start from the beginning with post one, or subscribe to follow along as the series unfolds.

If this kind of science-meets-teaching thinking is useful to you, this is what I do. The Tissue Literacy for Yoga Teachers blog at rubberbandmethod.com goes deeper — same lens, applied directly to hands-on assists and adjustments.

Read Tissue Literacy for Yoga Teachers

You’re exploring the nervous system side of yoga teaching—
how safety, regulation, and perception shape the classroom.

But there’s another layer:
→ how those states are reflected in the body.

This is where Tissue Literacy for Yoga Teachers comes in.

While nervous system literacy helps you understand why the body responds the way it does…

Tissue literacy teaches you how to feel those responses as they take shape in the tissues—through tone, resistance, and receptivity.

If you’re ready to explore how this shows up in hands-on teaching:

Tissue Literacy for Yoga Teachers →

This is the applied side of the work—
where the nervous system becomes something you can feel, and respond to, through touch.

The sympathetic nervous system is not your enemy. It is one of the most elegant, finely calibrated systems in the human body. And without it, you wouldn’t just struggle to handle stress — you’d struggle to get out of bed in the morning.

More Than Fight or Flight

“Fight or flight” is the phrase most people reach for when describing the sympathetic nervous system, and it’s not wrong — but it frames the entire branch around threat, which misses most of what it actually does.

The sympathetic nervous system is your activation branch. It mobilizes energy, sharpens attention, increases physical capacity, and prepares you to engage with whatever is in front of you. That includes threats, yes — but it also includes a challenging yoga sequence, an exciting conversation, falling in love, teaching a class you’re passionate about, or simply standing up from your chair.

Every time you move through your day with energy and engagement, your sympathetic nervous system is involved. It is the neurological infrastructure of being alive and participating in life.

What It Actually Governs

The sympathetic nervous system originates in the thoracic and lumbar spine — the middle and lower portions of your back — where nerve fibers exit the spinal cord and branch outward to reach virtually every organ and tissue in the body. Its reach is broad and its effects are coordinated: when it activates, it doesn’t just do one thing. It does many things simultaneously, all in service of preparing the body to meet a demand.

Here’s what sympathetic activation looks like at the level of physiology — and how it shows up in real life and in the yoga room:

The heart rate increases and the heart contracts more forcefully. More blood moves through the body per minute, delivering oxygen and fuel to where it’s needed most. In your classroom, this is the student whose chest you can visibly see pounding after a vigorous vinyasa sequence.

The airways dilate. Bronchodilation, the widening of the airways in the lungs, allows more air to move in and out quickly. Breathing often becomes faster and may feel more chest-dominant, supporting rapid ventilation. Slow diaphragmatic breathing can feel counterintuitive when activation is high, as if you’re working against the sympathetic current.

Blood is redistributed. Vessels supplying the large skeletal muscles — legs, arms, back — dilate to increase flow. Circulation to digestion decreases, and in acute stress the skin may pale as vessels constrict. During heat or exertion, however, skin blood flow can increase to help regulate temperature. The body is triaging resources in real time.

The pupils dilate. Vision sharpens and widens. You become more alert to movement in your peripheral field. This is the body scanning for information.

Sweating increases. Particularly in the palms and soles, a detail that is both evolutionarily useful (better grip on surfaces) and immediately recognizable to anyone who has ever been nervous before teaching.

Digestion slows. Saliva production decreases, gut motility slows, and digestive secretions are reduced. The body has decided this is not the moment to process lunch.

Non-essential immune and reproductive functions are temporarily deprioritized. In the short term, this reallocation is adaptive. Sustained over time, however, chronic activation can begin to disrupt immune balance and reproductive regulation.

The Neurochemicals: Epinephrine, Norepinephrine, and Cortisol

The sympathetic nervous system communicates through a specific set of chemical messengers. Understanding what they are, and what they actually do, goes a long way toward dissolving the idea that stress chemistry is inherently harmful.

Epinephrine (you likely know it by its other name, adrenaline) is primarily a hormone, released rapidly from the adrenal medulla (the inner portion of the adrenal glands, which sit atop each kidney) in response to sympathetic activation. It acts fast, within seconds, and its effects are immediate and dramatic: heart rate surges, airways open, blood sugar rises as stored glucose is released for fuel. Epinephrine is the chemical of acute, intense activation. It’s what you feel when you get startling news, narrowly avoid a car accident, or step onto a stage. It is also what makes a challenging yoga class feel exhilarating rather than merely exhausting.

Epinephrine clears from the bloodstream relatively quickly, within minutes of the triggering stimulus ending, if the triggering stimulus ends. It is designed for short, sharp responses, not sustained states.

Norepinephrine (also called noradrenaline) is both a neurotransmitter and a hormone. It’s released at sympathetic nerve endings throughout the body and also from the adrenal medulla alongside epinephrine. Where epinephrine is the acute spike, norepinephrine provides more sustained sympathetic tone. It’s responsible for vasoconstriction (the narrowing of blood vessels to redirect blood flow), sustained alertness, and focused attention. Norepinephrine is also central to mood regulation, it’s one of the key neurochemicals targeted by some antidepressants, which speaks to how deeply our emotional states are rooted in sympathetic chemistry. It has a somewhat longer half-life than epinephrine, lingering in the system for mere minutes in acute release, though its effects can persist as long as sympathetic nerves continue signaling.

Cortisol is a hormone and the neurochemical that gets the worst press — and the most misunderstood reputation. Released from the adrenal cortex (the outer layer of the adrenal glands) via the HPA axis, cortisol is not a sympathetic neurotransmitter in the strict sense, but it works in close concert with the sympathetic branch and is worth addressing here directly.

Cortisol is vital. Without it, you cannot regulate blood sugar effectively, and you lose a key hormone for modulating inflammation and immune activity. Your cortisol levels naturally peak in the morning — this is called the cortisol awakening response — and supports morning energy and readiness to engage with the day.

Cortisol also has a much longer half-life (roughly an hour or more) than epinephrine or norepinephrine. It clears more slowly than adrenaline, and its physiological effects can persist long after the initial stressor has passed. This matters for yoga teachers: a stressful commute, an upsetting phone call, or a difficult interaction before class isn’t just emotional, it’s biochemical, with a measurable duration. Your student who arrived flustered may still be chemically mid–stress response when they roll out their mat.

The problem with cortisol is not the hormone itself. The problem is chronic, unrelenting release, which is a story about lifestyle, load, and the HPA axis. We’ll go there in full in the next post.

Sympathetic Activation Is Not Suffering

One of the most important reframes a yoga teacher can make is this: a student in sympathetic activation is not a student who is failing at yoga. They are a student whose nervous system is doing its job.

Sympathetic activation is appropriate during vigorous movement. It is appropriate during challenge, novelty, and intensity. A well-designed vinyasa class should produce sympathetic activation, that’s part of why it feels good. The satisfaction of a strong practice, the heat that builds in the body, the sense of having met something difficult and moved through it — these are, in part, sympathetic experiences.

What yoga offers, and what makes it genuinely therapeutic rather than merely athletic, is not the elimination of sympathetic activation but the practice of moving through it and back toward balance. The sequence arc from dynamic warm-up to cooling postures to savasana is, among other things, a guided tour of the nervous system: mobilize, challenge, recover. Do it repeatedly, over years of practice, and you are essentially training the ANS to be more flexible — to activate fully when needed, and to release that activation when the demand has passed.

That’s not just a metaphor, this is one way yoga can train autonomic flexibility over time.

A Note on What’s Coming

The sympathetic nervous system doesn’t operate in isolation. Its hormonal partner, the HPA axis, which governs the cortisol cascade, runs alongside it and deserves its own careful examination. In the next post, we’ll look at what happens when the sympathetic branch and the HPA axis are activated chronically, what that does to the body over time, and why so many of your students may be walking through your door already running on fumes.

This is the second post in a foundational series on nervous system literacy for yoga teachers. Start from the beginning with post one, or subscribe to follow along as the series unfolds.

If you want to go deeper on how the nervous system informs hands-on teaching, this series grew out of the research behind my book Hands-on Yoga Assists: A Teacher’s Guide to the Rubber Band Method® — a practical guide for yoga teachers on anatomy-informed assists and adjustments.

We notice these things. And if we’re honest, we sometimes wonder: is it me? Is it them? Are they checked out, resistant, or just not trying?

Here’s a more useful lens: it’s their nervous system.

What you’re witnessing in those moments isn’t effort or attitude or even personality — it’s autonomic state. A nervous system that is highly activated shows up differently on a yoga mat than one that is shut down, and differently again from one that is genuinely at ease. These states aren’t chosen consciously. They’re shaped by what happened that morning, that week, or in some cases, years and decades before your student ever walked through your door.

You may have experienced this in your own practice — arriving wound tight from the day and leaving somehow softer, more focused, more yourself. That shift is real, and it’s physiological. If you want to understand why yoga produces it — and I mean actually understand it, at the level of biology rather than belief — the autonomic nervous system is where you have to begin.

Automatic Doesn’t Mean Untouchable

The word autonomic comes from the same root as autonomous: self-governing. Your autonomic nervous system (ANS) manages heart rate, digestion, pupil dilation, modulates aspects of immune function, glandular secretion, vascular tone, and dozens of other processes that your conscious mind never has to think about. Your heart beats while you sleep. Your stomach churns through lunch while you teach. Your blood vessels constrict when you stand up too fast — and your ANS corrects it before you even notice.

For most of history, this system was considered essentially inaccessible to conscious influence. A background operating system you couldn’t reach from the front end. You were along for the ride.

That assumption has been significantly revised. Researchers have identified specific structures — including a small cluster of neurons in the brainstem called the pre-Bötzinger complex — that help explain why deliberate changes in breathing can influence autonomic state.

It’s one of the more exciting areas of current neuroscience, and we’ll dedicate a full post to it later in this series. For now, it’s enough to know that the old idea of the ANS as completely beyond our influence is no longer the consensus view.

The body, it turns out, has left some doors open.

The Architecture: Brain, Brainstem, and Two Branches

The autonomic nervous system is part of the broader peripheral nervous system — the vast network of nerves that extends from the brain and spinal cord out into every organ, gland, and tissue in the body. But its command center lives primarily in the brainstem and hypothalamus, ancient structures that sit below the cortex (our outermost layer of the brain — the wrinkled surface you picture when you picture a brain) and operate mostly outside conscious awareness.

Think of the brainstem as the building’s utility room: unglamorous, largely invisible, and absolutely critical. It regulates breathing rhythm, cardiovascular function, and basic arousal states. The hypothalamus — a small but powerful region nestled near the base of the brain, just above the brainstem — acts as a master coordinator between the nervous system and the hormonal system. Together, they are constantly receiving information from the body and the environment and making real-time adjustments.

From this central command, two branches extend outward to govern essentially everything:

The sympathetic nervous system and the parasympathetic nervous system.

These two branches reach the same organs — the heart, the lungs, the digestive tract, the blood vessels, the skin — and they generally have opposing effects on them. Where one accelerates, the other decelerates. Where one constricts, the other dilates. You’ve probably heard sympathetic described as “fight or flight” and parasympathetic as “rest and digest,” and while those shorthand labels are useful starting points, they’re incomplete in ways that matter for yoga teachers. Each branch is nuanced, layered, and physiologically rich — rich enough that we’ll give each one its own dedicated post in this series.

They Never Fully Turn Off

Here’s where a lot of wellness education goes sideways: the sympathetic and parasympathetic branches are not a light switch. They are not on or off. They are not enemies.

At every moment of your life, both branches of the autonomic nervous system are active simultaneously. What changes is the ratio — which branch is more dominant, and by how much. Even in deep, restorative sleep, your sympathetic nervous system maintains a baseline of tone. Even in an acute stress response — a fight-or-flight moment — your parasympathetic system doesn’t go completely silent.

In fact, the nervous system can produce responses beyond fighting or fleeing. Sometimes the body becomes still and immobilized — a state often described as freeze — while in other situations a vasovagal response can lead to lightheadedness or even fainting. These responses reflect shifting patterns of sympathetic and parasympathetic activity, and they are a reminder that the nervous system’s responses to threat are more varied and complex than the “fight or flight” shorthand suggests.

For a long time, physiologists described the ANS as pursuing homeostasis — the idea that the body maintains fixed, stable set points and that health means returning to them after any disruption. Blood pressure at X, temperature at Y, cortisol at Z. Deviate, correct, return. It’s a tidy model, and it’s not entirely wrong — but it’s incomplete.

The more accurate picture is allostasis: the body achieves stability not by returning to fixed points, but by continuously adjusting those set points based on what life is currently asking of it. It’s predictive and adaptive rather than reactive and rigid. And it involves real trade-offs, because resources are finite. When the ANS floods the muscles with blood during a stress response, it pulls from digestion. When it sustains elevated cortisol to manage ongoing demands, it borrows from immune function, sleep quality, and reproductive health. The body is always robbing Peter to pay Paul.

When life allows for recovery — when the borrowing gets repaid — the system remains resilient. But when the demands are chronic and the debts accumulate unpaid, the physiological cost of that sustained adaptation adds up. Researchers call this allostatic load, and it’s one of the central mechanisms behind the persistent nervous system patterns we’ll be returning to throughout this series.

That capacity for flexible, fluid movement between states — mobilizing and then returning to baseline, activating and then genuinely settling — is increasingly understood to be one of the central markers of physiological health. The goal isn’t calm. The goal is flexibility.

Why This Matters in a Yoga Room

Your students walk into class already in some autonomic state. It was shaped before they arrived — by their commute, their sleep, their last conversation, and patterns that may go back years or decades. They don’t check that state at the door.

Your class is an environment. The way you sequence, pace, cue, and — for those trained to offer it — touch, either works with the nervous system or against it. A student who arrives in a low-activation state — already sluggish, flat, or shut down — may struggle to meet the demands of a fast, intense flow, skipping every chaturanga and retreating to child’s pose not because they’re lazy or unwilling, but because their nervous system is operating in a low-activation state that makes mobilization harder. Conversely, a student who arrives in high-activation — wired, anxious, or still running on adrenaline from the day — may find it genuinely impossible to settle into a slow yin class, fidgeting through every long hold and lying in savasana with their eyes open and their mind reeling.

Neither student is doing yoga wrong. Their nervous systems are doing exactly what nervous systems do.

You don’t need a neuroscience degree to teach yoga well. But understanding the basic framework of the ANS — what it is, what it governs, how its two branches function in dynamic balance — gives you a lens that makes your existing intuitions more precise.

This series is about building that lens, one layer at a time. In the posts ahead, we’ll go deep into the sympathetic branch, the parasympathetic branch, and the emerging science around how bottom-up practices — movement, breath, touch, sound — can influence this system in ways we’re only beginning to measure and understand.

The nervous system is not background noise in your classroom. It’s the whole conversation.

This episode is essentially the science behind why RBM exists. Chapter 1 of Hands-On Yoga Assists — The Science of Safe Touch — picks up exactly where we left off today. [Start with the book.]

Before we explore the work, here’s how it came to be.

On paper, I’m a yoga teacher, massage therapist, somatic practitioner, author and founder.

But none of that is why this space exists.

This space exists because I once lived at the furthest end of the stress continuum — with misdiagnosed Complex Post-Traumatic Stress Disorder.

For nearly eight years, I cycled through medications at staggering doses, navigating side effects I never fathomed could happen to me. When I was eventually referred for electroconvulsive therapy, I sought a second opinion instead — a decision that changed the trajectory of my life.

Getting the correct diagnosis of CPTSD set me on a path toward body-based methods rather than pharmacological ones. If I was going to heal, I needed to understand what was happening inside my own body.

So I began studying the nervous system — not academically at first, but experientially. I applied every somatic tool I could find and that was available at the time. I learned to track regulation and dysregulation in real time:

In my thoughts, reactions, sleep, appetite, ability to sit still, illness, and energy.

It was everywhere.

That season of my life became a kind of self-directed doctorate in awareness. I started to recognize patterns. I began to understand stress not as a vague concept, but as a continuum — one I had personally inhabited at its most dysregulated end. And day by day, through working with my body, I slowly walked myself back toward regulation.

Healing made me curious. Curiosity made me study.

I immersed myself in anatomy, physiology, biomechanics, stress chemistry, neurobiology, somatics, and philosophy. I wanted to understand not just that the body changes under stress — but how and why. I wanted language for what I had lived. And as that language developed, I found myself doing something I hadn’t expected: I started seeing the stress continuum everywhere. In the people around me. In the yoga rooms I consistently inhabited. In the way a student’s shoulders carried their week, or the way certain bodies couldn’t soften no matter how beautiful the sequence.

What began as self study turned into a lens through which I started to see the world and hold compassion for it.

Yoga was one of the somatic tools that profoundly supported my healing. But what truly moved the needle for me wasn’t only movement or breath. It was skillful, contextual, consensual touch.

Touch was a huge part of my life growing up — my mother was a massage therapist and massage educator–but I never considered touch as a tool that could be applied to anything other than soft tissue therapy. When I encountered touch as a somatic mind-body tool — it was at first by accident, then with growing intention — and it did something nothing else had managed to achieve. It invited a felt sense of safety — one that arrived in the body first, and only then reached the mind. It didn’t require me to cognitively reframe or analyze. It bypassed the thinking mind and spoke directly to the nervous system in a language older than words.

I later came to understand this through the science of co-regulation, afferent signaling, the vagal pathway, and the neurochemistry of oxytocin and cortisol — mechanisms we’ll unpack together in future posts. But at the time, I felt it first. In my body. As the missing link.

So when I became a yoga teacher in 2011, my intention was simple: share what helped. That was a combination of many somatic tools — asana, breathwork, meditation, mantra, but most importantly, consensual, skillful touch.

When offered with precision and awareness, touch can organize tissue, communicate safety, refine proprioception, and support regulation in ways words cannot. That understanding, refined over years in real yoga classrooms, eventually became Rubber Band Method^® — a structured methodology for hands-on yoga assists grounded in consent, anatomy, and nervous system awareness.

But this Substack is not simply about a method. Yes, it’s a somatic tool we will explore here because I feel it’s greatly undervalued and underutilized, but it’s not the primary focus. This Substack is about the foundation underneath RBM — what led to its formation. That foundation is nervous system literacy.

I’m sharing this because I think you deserve to know who is asking for your attention and why. Everything I teach, I have lived. The stress continuum isn’t an academic framework to me — it’s a map I drew from the inside. The science of co-regulation isn’t abstract — it’s the explanation for why touch was my missing link when years of other interventions hadn’t been enough. Rubber Band Method® exists because what helped me heal is teachable. And this space exists because the foundation underneath that methodology deserves its own exploration.

What I hope to share here is my unique lens on the yoga space — colored by decades of healing from severe dysregulation and nearly another decade moving back towards regulation. It’s still a daily journey that insists I continue to explore my internal state and how my environment affects it.

Having been practicing yoga since 2002, most of my healing journey was performed inside the yoga classroom. This led me not only to see the nervous system and its scientific frame emerge on the mat — it led me to connect yogic philosophy with modern science. To recognize where others might be on the stress continuum. To understand yoga as a living, breathing space for regulation.

And so, it is my sankalpa, my intention to explore three pillars through the lens of the yoga classroom:

Science — anatomy, physiology, stress chemistry, biomechanics, and how regulation and dysregulation manifest in the body.

Philosophy — how awareness shapes perception, how compassion arises from understanding, and how ancient frameworks intersect with modern neuroscience in ways that are, frankly, astonishing.

Application — what this looks like in real rooms, with real students, on real days.

My hope is that these posts inspire in you a fascination in the nervous system like it has for me. This inquiry is where I get to grow and expand alongside you as I put fingers to keyboard and articulate the science as I see it showing up in my classrooms. My hope is that what you learn here helps you have compassion for yourself and your students — even the ones who skip or fall asleep in savasana, insist on doing a thousand chaturangas even when you haven’t guided them to do so or find stillness an incomprehensible thing.

I’m not an academic or a scientist. I’m more like a living case study — I’ve lived the spectrum of the stress continuum and can attest to what works. Or, at the very least, share information about the mechanisms behind yoga and other somatic tools. Here, our inquiry unfolds in the living laboratory of yoga, where the nervous system is toned — or triggered. Through science, philosophy, and embodied practice, we explore regulation on the path toward samadhi.

Welcome to Nervous System Literacy for Yoga Teachers.

Let’s begin.

This newsletter is the science behind the method. The method itself is in the book — Hands-On Yoga Assists (Human Kinetics, 2025). If you're a yoga teacher ready to transform how you offer touch, that's your next step.

This Substack — and its companion podcast — explores anatomy, physiology, somatics, and research as they meet the realities of a real yoga classroom.

We explore the autonomic nervous system, the vagus nerve, co-regulation, consent, hands-on touch, and the ways ancient yoga wisdom often describes patterns that modern science is now able to study and measure.

New posts come out about twice a month.

I’m Kiara Armstrong — yoga teacher, massage therapist, somatic practitioner, founder of Rubber Band Method®, and author of Hands-On Yoga Assists.

I’ve practiced yoga since 2002 and have been teaching since 2011. But my real education in the nervous system didn’t begin in a classroom. It began during my path of healing from complex post-traumatic stress disorder.

That journey took me deep into stress physiology, autonomic regulation, and somatics — and what I learned changed how I teach and how I understand every student who walks into a yoga room.

If you want to understand not just that yoga regulates the nervous system — but how and why — follow Nervous System Literacy for Yoga Teachers on Substack, or wherever you get your podcasts.