But understanding why music matters is only half the equation. The more practical question is this: How do you actually create a playlist that supports the arc of a yoga class? If you’ve ever wondered where to begin, or why some playlists seem to carry a class effortlessly while others don’t, here’s a simple framework I think you’ll find useful.

Give Me the Beat

Years ago, I had a fitness instructor who’d once run collegiate track for USC, Division I, the real deal. He used to harp on me constantly about running with music. “Whether you realize it or not,” he’d say, “the music is setting your tempo.” I brushed it off the first few times. Then I actually paid attention. An up-tempo beat and my legs just wanted to move faster. A slower one and I’d naturally settle into an easier pace. He was right, and it wasn’t subtle once I started noticing it.

It turns out this effect is precise enough to build a workout around. Look up “Zone 3 running playlists” sometime and you’ll find entire libraries of music organized by beats per minute, engineered to help produce a specific physiological output. Not a vibe. An output. Runners aren’t choosing songs because they sound cool. They’re choosing songs because the tempo will, with a fair degree of predictability, become their tempo.

From a nervous system perspective, tempo becomes another environmental cue. Just as lighting, temperature, and the pace of your verbal cues influence a room, music quietly shapes the balance between mobilization and recovery throughout practice. If you’ve ever noticed a class shift when a track changes (bodies picking up, or softening, without you cueing anything different), that’s not a coincidence. That’s likely rhythmic entrainment at work. And if you’ve been building playlists on instinct alone, here’s a way to add even more intention to it.

A Nervous System Lens on Sequencing

You’ve heard me talk about thoughtful class sequencing in other posts because a well-built class tends to follow an arc. I think of it as a nervous system arc. It gently encourages sympathetic activation when effort is required, then creates the conditions for parasympathetic recovery as the practice winds down. The goal isn’t simply relaxation. It’s helping students practice moving fluidly between activation and recovery, what we might call autonomic flexibility. (If you want to learn more about that idea, see The Stress Continuum.)

The sequence builds, it peaks, it comes back down. Drawn out, it looks something like a bell curve. This is obvious in hatha and vinyasa, but it holds true even in yin and restorative classes, where some postures ask more of the nervous system than others even when nothing about the class reads as strenuous. Sometimes the effort is just in getting into the pose.

I build classes along six phases:

• Centering: helping the student arrive

• Warming: accessible postures, nothing too demanding yet, but starting to bring the student into the practice

• Heating: more stimulating, more challenging, pointedly preparing the student for where the class is headed

• Peak: the most demanding pose, or whatever the focus of the class happens to be (it might not even be a pose; it could be a breathwork practice)

• Cooling: bringing the student back down, reactivating recovery

• Integration: savasana, which the student should feel genuinely ready for by the time they arrive there

Here’s the part that matters for your playlist: if you consistently teach this arc, you can build music around the arc itself rather than around any single class. That playlist becomes reusable. You’re not starting from scratch every time you teach.

Matching Tempo to Phase

In centering, you want music that invites the student inward, physically and mentally, as they make their way to the mat. Tempo can begin to lift here, but gently. You’re not hammering anyone with intensity this early.

Warming and cooling often occupy similar tempo territory. Think of them as the middle gears of your playlist. During warming, those mid-tempo tracks gently encourage students toward greater movement. During cooling, a similar tempo supports the transition back toward rest without feeling abrupt. These are the songs that comfortably accompany a cat-cow flow without making anyone feel rushed.

Heating is where you can turn it up. More propulsive beats, quicker tempos, music that invites the nervous system toward greater mobilization. This is often in the middle part of class and encourages the students to get up from the mat and find their feet, really start to tap into their dristi or focus.

Peak is yours to decide. It might be a power song that matches the intensity of the pose or krama (a short wave of postures). It might, just as easily, be the moment you start pulling things back down so the student can actually be present in natarajasana instead of just holding it.

From peak, the music starts to descend, signaling to the parasympathetic branch that the effort is done and recovery is available. We move through cooling and then integration. And savasana? You already know what goes there. Chill. All the way down.

A simple gut-check as you build: does this track make you want to dance? It probably belongs in heating, not right before savasana. Does it feel deeply, unmistakably chill? That’s your centering or integration music. Anything that sits comfortably in between is your warming and cooling territory.

And side note, if you’re still thinking this doesn’t apply to Restorative or Yin, just listen to a Garth Stevenson album all the way through and ask your nervous system if each song evokes the same sense of intensity or calm.

Why This Isn’t Just a Mood

Two mechanisms are doing the real work here, and they’re worth knowing by name.

The first is rhythmic entrainment. Human nervous systems often synchronize movement, and sometimes aspects of physiology, to steady external rhythms. It’s why people unconsciously tap a foot, walk in time with music, or settle into the cadence of another person’s breathing. A faster beat tends to encourage faster movement; a slower beat tends to invite slowing. We don’t have to decide to do this. Much of it happens automatically.

The second is the vagus nerve’s relationship to sound more broadly. Sound can play a real role in the nervous system’s sense of safety, which means volume matters just as much as tempo, both the volume of the music and the volume of your voice if you’re speaking over it.

Tempo isn’t the only thing shaping the room. Volume matters. Musical complexity matters. Lyrics can capture attention while instrumental music often fades more easily into the background. Emotional tone matters too. A slow song in a minor key evokes something very different from a slow song in a major key, even if the tempo is identical. The nervous system is responding to the entire sensory experience, not just the beats per minute.

Pro tip:
If you want a source for music that reliably evokes feeling, try Shazaming your favorite films and shows next time something moves you. Composers for television and film are choosing those tracks deliberately, for exactly that effect, and it’s a genuinely useful place to go looking.

Try It

Next time you build a class playlist, build it around the nervous system arc rather than around a single class or mood. Once the tempo structure matches your sequencing, you may find the same playlist works for more classes than you expected, because the nervous system arc you’re teaching to doesn’t change nearly as much as the poses do.

If you try this, I’d love to know: do you already think about the nervous system when you build a playlist? And have you found a playlist that works across more than one class?

Great teaching isn’t just about sequencing poses. It’s about understanding the physiology of the people practicing them. Learn more in Hands-On Yoga Assists: A Teacher’s Guide to the Rubber Band Method®, where nervous system science meets practical application for yoga teachers.

Which brings us here.

This essay might still feel foundational, and honestly, that’s appropriate, because it still very much is. What we’ll be exploring today is the word somatic. You’ve almost certainly heard it. In wellness circles it has become something of a buzzword, appearing on retreat flyers and Instagram captions with the kind of frequency that can drain a word of its meaning.

But here’s the thing. It is an extraordinarily useful and accurate word for what happens in a yoga room. And here’s what I invite you to consider today:

What if, all along, as you’ve been teaching asana, weaving in breathwork, cueing students to notice sensation, maybe playing carefully chosen music or opening with mantra, possibly offering hands-on guidance, what if you’ve been leading somatic practices this entire time, without necessarily calling them that?

Today we look at what somatic actually means, the typical somatic tools found in most yoga classrooms, what these are doing for your students’ nervous systems, and why, buzzword or not, you’ve been a somatic practitioner right from the start.

What Somatic Actually Means

Somatic simply means of the body. Somatic practices are those that work through physical sensation and bodily experience to create change, not just in the muscles and fascia, but in the nervous system, emotional state, and psychological well-being. They are bottom-up rather than top-down. They bypass the analyzing, narrating mind and speak directly to the body’s own intelligence.

Many, if not most, tools in a yoga teacher’s toolbox are, at their core, somatic tools. Each one works through the body to regulate the nervous system. Each one speaks the language the nervous system actually understands: sensation, rhythm, breath, contact, rather than asking the thinking mind to do the heavy lifting.

Let’s look at what you’re already doing.

Asana and Skillful Sequencing: Training Both Branches

Asana may be the most obviously somatic tool in the yoga teacher’s kit and yet its effects on the nervous system are often the least examined. We talk about poses in terms of alignment, anatomy, and sensation. We talk less often about what individual postures and their sequencing are doing to the autonomic nervous system in real time.

Let’s look at both.

Individual poses have specific, documentable physiological effects that go well beyond stretching and strengthening. Inversions, for example, shift the distribution of blood and fluid toward the upper body and head, stimulating baroreceptors, pressure-sensitive receptors in the neck and chest, that can signal the brain to lower heart rate and blood pressure. The parasympathetic branch responds to do this. The body settles. This happens in a supported legs-up-the-wall pose just as readily as in a full headstand. The nervous system doesn’t require the advanced expression of the pose to receive the benefit.

Sun salutations practiced with one breath per movement do something different but equally precise: they synchronize breath and body into a moving rhythm that tends to draw attention out of the thinking mind and into felt physical experience. This is bottom-up regulation in motion. The cognitive noise quiets not because the student decided to stop thinking, but because the body gave the nervous system something more immediate to attend to.

And savasana, perhaps the most underestimated pose in the entire practice, places the body in full contact with the ground, removing the muscular effort of even sitting upright, and creates physiological conditions associated with a predominantly parasympathetic state. It is, quite literally, as grounding as a pose can be.

These effects are available in any class, regardless of style or intensity. Chair yoga has somatic effects. A slow yin practice has somatic effects. A single mindfully held pose has somatic effects. The nervous system is always responding to what the body is doing, and asana, in any form, is always speaking to it.

But here is where intentional sequencing amplifies everything.

Not every teacher has been trained in a formal sequencing arc, but once you understand the two branches of the autonomic nervous system, a general outline begins to emerge. Even in a restorative class, a yin practice, or a chair sequence, each and every pose can elicit more of a stimulating (think sympathetic) or calming (think parasympathetic) response. The invitation here is not to impose a single model but to bring nervous system awareness to whatever yoga style you’re already working within. To ask: which poses are more stimulating? Which are fundamentally more calming? What arc am I trying to produce? One that rises and falls throughout class? Starts high and gradually declines? Follows a bell curve, building toward a peak before descending into recovery?

Because here’s the reality: whether it’s vinyasa or restorative, physiologically speaking, sukhasana is generally more stimulating than savasana, shoelace more stimulating than supine twist, and so on.

When those questions inform your sequencing, even loosely, even intuitively, the somatic effects of the individual poses can compound. The class becomes more than a collection of shapes. It becomes a guided experience of the nervous system’s full range: activation and recovery, effort and ease, the gas pedal and the brake, with a teacher at the helm who understands what they’re actually training.

Mantra: Toning the Vagus Nerve Through Sound

When students chant Om, something physiological is happening alongside the devotional intention. The extended exhale, the vibration resonating through the throat and chest, the low hum that lingers after the sound fades, all of this directly stimulates the vagus nerve.

The vagus nerve interfaces directly with the structures involved in vocalization and breath. Humming, chanting, and singing all create vagal activation through this pathway. Research on chanting has documented reductions in cortisol, heart rate, and anxiety, alongside increases in heart rate variability, that key marker associated with autonomic flexibility and regulation.

When you lead a class in Om, you are initiating a vagal toning practice before a single pose has been cued. You are beginning the process of shifting students from the sympathetic dominance most of them carried through the door into a more regulated, receptive state. The ritual and the neuroscience are not separate things. They are the same thing, described in different languages.

Music: Entrainment and the Regulated Room

The playlists yoga teachers agonize over are doing real physiological work. And when viewed through the lens of co-regulation and entrainment, it becomes easier to understand why.

Entrainment is the phenomenon by which the body’s rhythms, heart rate, breathing rate, and brainwave activity, naturally begin to synchronize with a steady external rhythm. Music with a slow, deliberate tempo literally invites the body toward a slower, steadier physiological state. Not because the student decides to match it, but because the nervous system is wired to entrain to rhythmic signals in the environment.

Beyond rhythm, music activates the brain’s reward circuitry, stimulating dopamine release, the same neurochemical heavily involved in reward, motivation, and the touch response. Slower, more melodic music supports alpha and theta brainwave activity associated with the relaxed alertness and meditative states you’re deliberately cultivating. And music, like mantra, travels through the auditory-vagal pathway. The vagus nerve is connected to the muscles of the middle ear, which are tuned specifically to the frequency range of the human voice, the range most music occupies.

And just as asana can be sequenced to move the nervous system through activation and recovery, music can support that same arc. An upbeat, driving rhythm during a heating phase isn’t just energizing, it’s entraining the nervous system toward sympathetic activation, supporting the very mobilization the poses are asking for. A slower, melodic track in cool down isn’t just atmospheric, it’s signaling the nervous system that the effort is complete and recovery is available. A thoughtfully curated playlist doesn’t just match the energy of the class. It shapes it by moving through the full range of the autonomic nervous system alongside the sequencing as an added tool.

Your playlist is a nervous system intervention. The care you invest in it translates directly into the physiological experience of your students. You already knew this intuitively. Now you know why.

Pranayama: The Master Regulator

Of all the somatic tools in yoga, breathwork is perhaps the most direct and the most well-researched pathway to nervous system regulation. The mechanism is elegant in its simplicity: the breath is the one autonomic function we can consciously control.

When we slow the breath and lengthen the exhale, we manually engage the parasympathetic branch. The vagus nerve is stimulated with every exhalation. This is why a long, slow exhale calms the heart. It’s why box breathing, alternate nostril breathing, and extended exhale practices all produce measurable reductions in cortisol and anxiety. We are literally using the breath to press the brake pedal.

But the breath can just as deliberately press the gas. Practices like kapalabhati (skull shining breath), rapid, forceful exhales in quick succession, and bhastrika, the bellows breath, activate the sympathetic branch, increasing energy, heat, and alertness. The breath rate accelerates, oxygen exchange intensifies, and the nervous system responds with mobilization rather than rest. Used intentionally and at the right moment in a class, these practices are sympathetic activation tools just as precise as any heating pose. The breath, in other words, can drive the full arc of the nervous system and not just the return to calm.

Pranayama also cultivates both proprioception and interoception, two distinct but complementary dimensions of body awareness. Consider the three-part yogic breath: can the student breathe into just the belly, then expand only into the lower ribs, then finally fill the upper chest toward the collarbones? And can they reverse it, letting the collarbones drop, the lower ribs release, the belly deflate, in deliberate sequence? This practice, over time, trains proprioception: the gross body awareness that asks can I do this, and how? It builds a more precise, more inhabited relationship with the physical body from the inside out.

Interoception goes a layer deeper, into the felt sense of what the breath is doing to the internal state. Notice the quality of alertness and heat that builds during kapalabhati. The buzzing aliveness after bhastrika. Then contrast that with the unmistakable settling that follows a round of box breathing or an extended exhale. That felt sense of activation or of easing down is interoception. The body reporting its own state, and the practitioner learning to read the report. Both of these capacities, proprioceptive precision and interoceptive awareness, deserve their own dedicated exploration, and we’ll go deep on each in future essays. For now, understand that every time you guide students into conscious breathwork, you are training both. You are developing their capacity to inhabit their bodies more fully.

And a student who inhabits their body more fully receives everything else you offer, more completely.

Touch: The Somatic Tool That Speaks Directly

Now, where does touch fit in this picture?

Touch works through every mechanism we’ve just described and then goes further.

Like mantra and pranayama, safe touch can stimulate vagal activity and shift the autonomic nervous system toward parasympathetic activation. Like music, it triggers dopamine, as well as serotonin and oxytocin. It quiets the overactive thinking mind, not by training it, but by bypassing it entirely through bottom-up regulation. Research on safe, consensual touch consistently documents these kinds of effects across numerous studies and populations.

But touch has something the other tools don’t.

Touch works directly on body awareness itself.

When a warm hand makes intentional contact with the body, something immediate and specific happens: attention is drawn into the body at exactly that location. Not because the student decides to pay attention there, but because the nervous system orients toward sensation automatically. Proprioception, the continuous stream of information from muscles, joints, and tissues that tells the brain where the body is in space, is sharpened and clarified at the point of contact.

This matters enormously in a yoga context. Many students, particularly those carrying stress, chronic tension, or histories of disconnection from their bodies such as with dissociation, move through asana without necessarily fully inhabiting the poses. They execute the shape without feeling it from the inside. The pose is performed rather than experienced or embodied.

A well-placed hands-on assist or adjustment changes this immediately and tangibly. When a hand arrives at the outer knee in warrior two, the sacrum in child’s pose, or at the feet in savasana, the student is suddenly, vividly there. Present in that part of their body in a way they may not have been a moment before. The proprioceptive signal is clarified. Body awareness deepens. The pose stops being a shape and starts being an experience.

And like the other somatic tools we’ve explored in this essay, skillful hands-on teaching also cultivates interoceptive awareness. This broader capacity to sense and interpret the body’s internal state may be one of the most profound and under-discussed effects of an embodied practice. Whether the teacher recognizes it or not, the student’s nervous system registers every moment of contact. That contact can be disruptive or deeply supportive. Which is precisely why it should always be harmonious with the practice, skillfully delivered, and of course, consensual.

This is embodiment work. And it is one of the most significant and least discussed benefits of skilled, consensual hands-on teaching in a yoga context.

The Through-Line

Step back, and here is what you see.

Asana. Mantra. Music. Pranayama. Touch. These are not separate tools that happen to live in the same tradition. They are variations on a single theme and different pathways toward the same fundamental goal: a nervous system that is being actively trained, in both directions, toward greater range, greater resilience, and greater capacity to regulate itself. Not just calmed. Not just activated. But flexible. A body that is inhabited rather than merely occupied, and a student who is present enough to receive what the practice is offering.

This is what most yoga teachers are already doing, in every class, often without realizing the full scope and benefit of what they’re offering. Every playlist curated with care. Every pranayama practice designed to energize or to settle. Every asana sequence that builds toward effort and guides students back through recovery. Every moment of skilled, consensual contact that draws a student more fully into their own body. All of it is nervous system training. All of it is contributing towards widening the window through the use of somatic tools.

Rubber Band Method® places touch within this same context deliberately. An RBM assist or adjustment is not a thoughtless technique applied to a body. It is an intentional somatic intervention, one that works through the same neural pathways as other somatic tools within the yoga practice.

You have always been doing this work. Now you have the science to understand why it works, and the methodology to do it with the skill and intentionality it deserves.

If this resonated with you and you work with bodies as a yoga teacher, I’d love for you to explore how the Rubber Band Method® approaches hands-on assists and adjustments through an anatomy-informed, consent-centered lens. You can find trainings and resources at rubberbandmethod.com.

This essay, the final one in this foundational series, is the one that matters most to me personally, because it’s not only where science meets yoga philosophy, but it’s where both intersect with my own lived story. If you’ve read everything that came before this, thank you. This is what it was building toward.

Because here’s the question underneath all of it: why learn anything about the nervous system?

And here’s my answer: because it’s at the heart of everything. It’s at the heart of why yoga works. The avenue through which Patanjali was trying to guide us all along, long before humanity had words for it. And the answer for how we face the single greatest challenge in every single human being’s life: stress.

Here’s the thing about stress: we’ve all been sold a lie.

Not intentionally, maybe. But somewhere along the way, “stress” became a dirty word — something to eliminate, avoid, manage into oblivion. We talk about it the way we talk about a diagnosis. Something wrong. Something to fix.

But stress isn’t inherently bad. And yes, I just said that as someone who once had complex PTSD. If anyone had reason to write stress off entirely, it might be me. And I still won’t, because this is too important to collapse into something simple.

Some stress is not only good for you, it’s necessary for growth, resilience, and a well-regulated nervous system. And in fact, stress can be the very thing that teaches us compassion and lends us wisdom. The problem isn’t stress itself. The problem is where you land on the stress continuum, and whether your nervous system has the capacity to return to baseline after the experience. We’ve been pointing to this all along: to train nervous system flexibility, to have resilience, is to train both branches of the autonomic nervous system. That includes the sympathetic branch.

Let me walk you through the full spectrum of what we term “stress.”

The Stress Continuum

Think of stress not as a single thing but as a range, a long line stretching from mildly challenging all the way to traumatic. Where any given experience lands on that continuum depends on a lot of factors: intensity, duration, frequency, context, and perhaps most importantly, your nervous system’s current capacity to process and recover; it’s flexibility.

At one end, you have stress that builds you. At the other end, you have stress that breaks something open that doesn’t close back up on its own. Most of us live somewhere in the middle, moving up and down the line depending on the day, the season, the decade.

Understanding where you are, and where your students are, changes how you work with bodies. It changes how you teach. It changes how you live.

Eustress: The Good Stuff

Eustress is the term coined by endocrinologist Hans Selye in the 1970s to describe stress that is positive, motivating, and within our capacity to handle. The prefix eu- comes from Greek, meaning “good” or “well.”

Eustress is the flutter before a performance. The focused tension of a deadline you actually care about. The physical challenge of a hard yoga class. The nervousness before a first date or a public talk. It’s the stress that sharpens you.

Physiologically, eustress activates the sympathetic nervous system, heart rate increases, attention narrows, energy mobilizes, but in a way that feels enlivening rather than threatening. And critically, once the stressor passes, the system returns to baseline without much trouble.

Eustress is associated with improved performance, increased motivation, a sense of meaning, and can enhance immune function. It involves a stressor, but it feeds you.

Hormetic Stress: The Dose Makes the Medicine

Hormesis takes this a step further. Hormetic stress refers to a biological phenomenon in which a low-to-moderate dose of a stressor produces an adaptive, strengthening response, even when higher doses of the same stressor would be harmful.

Cold plunges are a great modern example. Immersing yourself in cold water is a stressor. Your body doesn’t love it at first. Your sympathetic nervous system fires hard, cortisol spikes, your breath goes ragged — maybe you instantly pee yourself like I always did! But with repeated, controlled exposure, your system adapts. You get better at tolerating and recovering from cold.

That’s the point of hormetic stress. It trains your stress response. With repeated exposure you recover faster, regulate more efficiently, and become more flexible, both in your nervous system and in your response to the stressor itself.

Exercise is hormetic stress. Fasting can be hormetic stress. Heat exposure, certain plant compounds, intermittent breath holds, all hormetic. The principle is consistent: the body, given the right dose of challenge with adequate recovery, adapts.

This is not a metaphor. It’s physiology. And what hormetic stress specifically trains is resilience, resilience in the nervous system, the body, and the mind. That’s not a side effect. That’s the mechanism and the foundation of autonomic flexibility. Which brings us directly to what building that resilience actually looks like over time.

Widening the Window

There’s a concept I want to name here because it’s central to everything: the window of tolerance. Developed by psychiatrist Daniel Siegel, it describes the zone of nervous system arousal — or stress — within which a person can function, process experience, and remain regulated. Not numb, not flooded, present and capable.

What hormetic stress and eustress do, over time, is widen that window.

Every time you take the cold plunge and come back to baseline, you’ve practiced the full arc: activation, peak, recovery. Every time you move through a hard yoga class and soften at the end, your nervous system files that experience. I went there and came back. The window expands. What used to throw you off now barely registers. What used to flood you now just gets your attention.

This is stress resilience, essentially your ability to be flexible to stressors and have the capacity to recover. You build resilience the same way you build physical strength: by showing up to appropriate challenges, recovering well, and repeating. At its heart, this is toning both branches of the nervous system, the sympathetic to activate at the capacity needed for the challenge, and the parasympathetic to allow you to adequately recover. Widening the window isn’t about becoming numb to stress. It’s about becoming more flexible to it.

When Stress Exceeds Capacity: Trauma

Here’s where the continuum shifts.

When a stressor exceeds the nervous system’s current capacity to process and integrate, whether because of its intensity, its duration, its unpredictability, or the absence of support and safety, the system doesn’t complete its natural arc. It gets temporarily stuck.

This is trauma. Not a character flaw. Not weakness. A nervous system response to an experience that was simply too much, too fast, too long, or too alone.

Trauma isn’t defined by the event itself. Two people can go through the same experience and have profoundly different responses based on their history, their window of tolerance, their access to co-regulation, and a dozen other factors. What traumatizes one person may barely register for another, and that doesn’t make either person wrong. It makes us human, with different nervous systems shaped by different lives.

What’s worth distinguishing is what trauma can look like when the system has what it needs to move through it. When the stressor hits and the system is pushed hard, very hard, what follows is a natural, healthy response: grief, rage, fear, shock, or some combination of usually very intense emotions. The nervous system fires at full capacity. That acute response can last hours, days, sometimes a couple of weeks. But given enough time, enough safety, and enough support, it can run its course. The system metabolizes what happened and files it alongside other significant life events as a learning lesson. One the system can return to as perhaps greater caution, but not as something unresolved. Not stuck. That’s one generalized example of trauma completing its arc. The system metabolizing what it was given.

This is not the same as the event not mattering. It mattered. Your nervous system learned something from it. But phobias didn’t form, relationships weren’t fractured over the long term, and your health wasn’t chronically impacted. The experience was real and difficult, and the system did what it was designed to do: respond, process, and recover.

PTSD and CPTSD: When Trauma Becomes a Condition

It’s worth naming clearly: experiencing trauma does not mean a person has PTSD. PTSD is a clinical condition that can develop in the aftermath of trauma when the nervous system cannot fully complete that arc of metabolization. When the experience was simply too much, too fast, too long, or too alone for the system to integrate at the time, it gets stuck.

Post-Traumatic Stress Disorder develops when the nervous system remains dysregulated long after the threat has passed. And here is what “stuck” can look like over time: what began as an acute startle response, a natural alarm that fired when it needed to, doesn’t resolve. It becomes adaptive. The nervous system, trying to protect the person from future threat, reorganizes itself around that unmetabolized experience. Hypervigilance sets in, along with numbness or dissociation, shame, and a startle response that won’t settle. Intrusive memories, nightmares, avoidance, emotional reactivity — these are the nervous system’s continued attempts to process something it couldn’t fully metabolize in the moment. And over time, these adaptations can stop being just symptoms and start shaping life globally: relationships can fracture, social engagement might narrow, work can suffer, and physical health may be impacted in ways that can feel entirely disconnected from the original event.

Complex PTSD is related but distinct. Where PTSD often follows a single event or a defined period of trauma, CPTSD is associated with prolonged, repeated trauma, particularly when it occurred in a context of captivity or powerlessness: childhood abuse, domestic violence, chronic neglect, prolonged medical trauma. CPTSD carries all the hallmarks of PTSD but adds layers of profound difficulty with self-concept, emotional regulation, and relationship, because the trauma wasn’t just what happened. It was the ongoing environment in which the person had to survive and, by extension, had to adapt who they were to get through it. The coping strategies, relational patterns, and beliefs about self that formed during that period were genuine survival responses. The painful part is that they don’t simply switch off when the environment does.

Both conditions represent a nervous system that got stuck at the far end of the continuum. And while only a small percentage of people receive a formal diagnosis, diagnosis doesn’t equate to prevalence. Not everyone has access to a provider. Not everyone seeks help. Diagnosed or not, individuals with these conditioned nervous systems will end up in your classroom, whether it’s a Trauma-Informed Yoga class or not. They are there.

Which is why tactful consent is paramount to a safe classroom environment. And why fostering agency and upholding student autonomy is exactly what supports these individuals.

I know this firsthand. I was the student who would walk into yoga class and lay in savasana the entire class. That would drive most yoga teachers hell-bent on “controlling space,” ahem, I mean “holding space,” simply mad. But why did I do it? Because the vibes, my teacher’s presence and voice, even the other students’ energy, the atmosphere itself, was so calming. But my poor CPTSD-conditioned nervous system simply couldn’t muster the effort to move through any other pose than savasana. So I laid there, healing by osmosis from the collective yoga vibes. That was me exercising my agency. And my teacher respecting my autonomy. Agency: the choice. Autonomy: the freedom to exercise it.

Whether you know it or not, these students are in your classroom. Support them, with clear consent and respect for their agency and autonomy.

When the Poison Becomes the Medicine

There is something that lives on the other side of the hardest end of the continuum that doesn’t get talked about enough. Not because it isn’t real, but because you can only see it from the other side, and not everyone makes it there.

It’s called Post-Traumatic Growth, a term coined by psychologists Richard Tedeschi and Lawrence Calhoun in the 1990s to describe the positive psychological change that can emerge from the struggle with deeply challenging, even devastating life experiences. Not in spite of the trauma. But because of the reckoning with it.

I want to be careful here, because PTG is not a guarantee, it’s not a silver lining to be prescribed, and it is absolutely not a reason to minimize what someone has been through. A friend of mine was recently diagnosed with PTSD and had never once heard of Post-Traumatic Growth. When I told her it existed, something shifted in her face. Not relief exactly, but possibility. That’s what I want to offer here: not a promise, but a door worth knowing about.

Because here’s what I’ve lived: I cannot say I’m grateful for what happened to me. If I could wave a wand and make sure those experiences never occurred, I would do it without hesitation. But that’s not possible. And when you arrive at the end of that road, when every other option has been exhausted, what remains is acceptance. Not resignation. Not pretending it was okay. Pure, unadulterated acceptance of the ugly things you endured.

And when that acceptance comes, something fundamental shifts. It doesn’t reverse the identity reformation that happened in survival mode. What it introduces instead is an incomparable compassion. Compassion steeped in a complete absence of judgment, for yourself and for others, because you have lived inside the darkest mechanics of being human and came out the other side knowing exactly how someone ends up there.

You also gain wisdom. Lessons about yourself and about humanity that, from where I stand, no other experience could have taught you. It’s almost like your window gets utterly shattered. Just shards and pieces left of yourself, if you truly reach that far end of the continuum. But as you work your way back, as you pick up those pieces, put them together, and heal what you have access to, you build a wider window than you ever had before.

That is Post-Traumatic Growth.

Why This Matters in a Yoga Context

The student who goes rigid when you approach. The student who cries in savasana without knowing why. The student who pushes past their edge every single class and can’t seem to stop. The student who dissociates in deep hip openers. The student who, when you provide them an assist, sighs like they haven’t breathed in years. These and countless other representations of nervous systems expressing their position within the continuum abound in every classroom.

Every nervous system is on the continuum. And so is yours.

But here’s the thing: you’re a yoga teacher, you work with nervous systems. Full stop. Every cue, every playlist, every hands-on assist lands somewhere on this continuum for the person receiving it.

And here’s what’s worth sitting with: yoga, in its fullness, is one of the most sophisticated nervous system tools humanity has ever developed. Not because it was designed in a laboratory, but because across thousands of years of practice and observation, it arrived at the same destination science is only now catching up to. Asana moves the body through activation and release, training the full arc of the stress response. Breathwork directly modulates the autonomic nervous system, shifting state from the inside out. Mantra, drishti, music, and class structure shape the environment of safety that determines whether a nervous system can regulate or not. Meditation and silence ask the student to simply be present with themselves, building the top-down awareness that makes regulation possible off the mat. And consensual hands-on teaching, offered with skill and respect for student autonomy, provides a quality of co-regulation that might be difficult to access through verbal cueing alone.

All of it, every tool in the yoga teacher’s hands, is in the business of widening the window.

Understanding this doesn’t make you a therapist. It makes you a more informed teacher, one who knows that the body is always doing something intelligent, that stress isn’t the enemy, and that the ancient practice you’re holding is doing something far more profound than improving flexibility. It is, when offered well, supporting the single greatest challenge every human being faces.

This is not peripheral to yoga. This is the center of it.

Stress Is a Teacher

The goal is not a stress-free life. A stress-free life is a stagnant one.

The goal is a nervous system that can meet challenge, move through it, and return home to itself. A nervous system with enough resilience and flexibility that the inevitable stressors of being alive don’t shatter you. They shape you. And sometimes, as we’ve explored, they may shatter you first, but what gets rebuilt ends up wider and wiser than what existed before.

Few yoga sages lived within our chaotic, demanding, often disembodied world. They lived within curated environments adapted for introspection, meditation, and less stimulation, so that samadhi, enlightenment, can emerge. We modern yogis get to learn how to do that outside those ideal conditions. And yet we challenge ourselves with the same staggering goal, on a modern path sprinkled with unpredictable, hidden landmines — what our nervous systems perceive as stressors — one after another, often without warning.

In spite of the landmines, when we shift our perspective towards finding liberation, ananda, we can get there faster. We see that it’s a journey supported, and sometimes hindered, by the resiliency of our nervous system rather than our capacity for 108 sun salutations or our ability to do a handstand. This reframing allows us to genuinely internalize what Patanjali meant by abhyasa and vairagya. Not as a daily inversion practice or enduring a grueling vinyasa series with poise, but as dedicated practice toward non-reaction. In modern, scientific terms: widening our window of tolerance.

This is what Patanjali was always pointing at. Not perfection of posture. Not the performance of calm. But the training of our nervous systems to be resilient enough to meet the full spectrum of being alive. And to move ourselves back, with as much grace as we can muster, from anywhere we find ourselves on the continuum.

To be on the yogic path is to be on a journey to train the nervous system to widen its window. To have the capacity — through the exhilaration of eustress, the intentional training of hormetic stress, and even the navigation of all the more challenging points further along the spectrum — to bring ourselves back toward regulation. And when we can’t, when life deals us a landmine that leaves us stuck at one end, as it did mine, then our ultimate yogic lesson has begun. That of compassion.

Because what is it to be a yogi, truly, if not to hold searing compassion — for others, yes, but starting first with ourselves.

This is the ninth and final essay in the foundational series on nervous system literacy for yoga teachers. If you’re just finding this work, start from the beginning with The Autonomic Nervous System: Your Invisible Co-Teacher, or subscribe to follow along as we move into new territory from here.

Join me in Bali next month, August 15-29, 2026 as we explore the nervous system and so much more within the lush jungle backdrop of Selemadeg. The Samasthala 200HR YTT explores the full range of yoga concepts and presents Rubber Band Method® assists as a complimentary teaching tool in any class. Book today and save £500 or $650!!

This essay is about something slightly different: how it communicates.

Specifically, how the brain and body talk to each other. And perhaps more importantly, who is doing most of the talking.

The answer has some genuinely surprising implications for yoga. For why embodied practice works as deeply as it does. And for every heart-centered teacher who has ever trusted a feeling they couldn’t quite explain.

Two Directions of Travel

Every nerve fiber in the autonomic nervous system carries information in one of two directions: from the brain to the body, and from the body to the brain.

Efferent signals travel outward and downward, from the brain to the body. A simple way to hold this: E for efferent, exits the brain. The brainstem tells the heart to speed up. The hypothalamus initiates a cortisol cascade. The autonomic nervous system adjusts vascular tone in response to a shift in posture. These are efferent signals. The vast majority of them happen completely outside conscious awareness, automatically and continuously, every moment of your life.

Afferent fibers carry signals in the opposite direction, upward from the body to the brain. A for afferent: think answers from the body. They are the body’s continuous reporting system, sending information about the state of every organ, every tissue, and every internal environment. Messages such as: heart rate is elevated. Gut motility has slowed. Breathing is shallow. Muscles are fatigued. Afferent fibers are the body talking and the brain listening.

Both the sympathetic and parasympathetic branches contain both kinds of fibers. Neither branch is a one-way command system. Both are in constant, bidirectional conversation. Sending instructions downward. Receiving status reports upward. Simultaneously, without pause.

If the earlier essays painted a picture of the autonomic nervous system as something that acts on the body, this essay adds the other half of that picture. The body is not a passive recipient of neural commands. It is an active, continuous contributor to the conversation. And as we’re about to see, it may be contributing more than we might assume.

The Vagus Nerve and the Listening Brain

Here is where the anatomy gets particularly striking.

The vagus nerve, as we established in earlier essays, is the primary vehicle of the parasympathetic branch. It wanders from the brainstem through the neck, chest, and abdomen, innervating the heart, lungs, and digestive organs along the way. It carries both efferent and afferent fibers. Brain-to-body instructions and body-to-brain reports traveling together through the same nerve.

But they are not traveling in equal proportions.

Research confirms that approximately 80% of the fibers in the vagus nerve are afferent. Only around 20% are efferent.

In the specific pathway between the heart and the brain, the numbers are even more telling. The heart is sending far more signals upward to the brain than the brain is sending downward to the heart.

Let that sit for a moment.

The organ most associated in virtually every human culture with feeling, intuition, love, and inner knowing is, neurologically speaking, doing most of the talking in its relationship with the brain. The brain, by contrast, is mostly listening.

The HeartMath Institute has built an entire body of research around this afferent relationship. They explore how coherent heart rhythm patterns, the kind associated with calm and positive emotional states, send stabilizing signals upward through the vagus nerve to the brain, influencing emotional regulation and even cognitive performance. We’ll look at HeartMath and their research in a future essay. For now, it’s enough to say that the heart-brain conversation is real, it’s predominantly traveling upward, and your yoga practice has been engaging it all along.

A Body Built for Reporting

The vagus nerve is the most dramatic example of afferent dominance in the body. But it is not the only one. And for yoga teachers, knowing where else the body is predominantly sending rather than receiving is directly practical.

The gut is one of the most afferent-rich structures we have. Its own enteric nervous system contains hundreds of millions of neurons, often described as rivaling the spinal cord in complexity. It produces the majority of the body’s serotonin. And like the vagus nerve it’s connected to, it sends far more signals upward to the brain than it receives coming down. When people talk about gut feelings, the neural infrastructure to support that is real. The gut isn’t just processing lunch. It is in constant conversation with the brain, and it is doing most of the talking.

The skin is the body’s largest sensory organ. Every point of contact generates afferent sensory signals that travel upward to the brain. A hand on a shoulder. Feet pressing into a mat. The temperature of a room. Touch is not processed passively. It is reported actively, and the brain responds to what it receives. This is part of why skillful, consent-based, well-applied touch can be so profoundly regulating. It is not just a mechanical event. It is an afferent input that the brain reads as information about the safety of the environment.

Muscle spindles are small sensory organs embedded within muscle tissue throughout the body. They send continuous proprioceptive signals to the brain and spinal cord about muscle length, stretch, and rate of change. Every yoga pose generates this input. Every transition between poses generates it. The body is narrating its own experience upward, moment by moment, throughout the entire yoga practice.

Put all of this together and the picture that emerges is one of a body that is, in many ways, leading the conversation with the brain. The nervous system is not a top-down command structure. It is a bidirectional network in which the body’s continuous reporting shapes, updates, and redirects the brain’s responses in real time.

Bottom-Up and Top-Down: Two Ways to Shift State

What’s worth naming here is that the two-way conversation between brain and body doesn’t just describe how the nervous system works. It maps directly onto how we can work with it. The direction of the fibers and the direction of our regulatory tools are the same conversation. We have two pathways for influencing our mental and emotional state: we can enter from the top, through the thinking mind, or we can enter from the bottom, through the body. Understanding afferent and efferent fibers gives us a road map for how regulation through either of those entry points actually occurs.

This illuminates something every yoga teacher has observed but may not have had the language to fully explain: why changing what the body is doing can change how the brain is functioning, even when the thinking mind hasn’t caught up yet.

This is what we mean by bottom-up regulation. It is the use of body-based inputs, movement, breath, touch, sound, and sensation, to shift neural and emotional states from the body end of the conversation upward. When a student slows their breath, lengthens their exhale, receives a well-timed hands-on assist, or feels the grounded weight of their body in a supported pose, they are generating afferent signals that travel upward through the nervous system. Those signals update the brain’s assessment of the body’s state. The brain receives the updated report and adjusts its output accordingly.

Critically, this process is largely unconscious. The student doesn’t have to consciously decide to slow down or talk themselves into relaxation. The body sends the signal. The brain receives it. The shift happens, often before the thinking mind has registered anything at all. This is precisely why bottom-up approaches reach people that purely cognitive tools sometimes cannot. They can bypass the cortex rather than depending on it. When someone is deep in a stress response, or simply too exhausted to think their way anywhere useful, the body still has a direct line to the brain. And that line runs through afferent fibers.

Top-down regulation works in the opposite direction. It is the conscious, intentional use of thought, reframing, reasoning, or directed attention to influence physiological state. Journaling. Cognitive reframing. Talking through a problem with a therapist. These are top-down tools, and they are genuinely valuable. They have their place. But they depend on cortical availability. The thinking brain needs to be sufficiently online to do the work. In states of high activation or significant shutdown, that availability is often limited.

This is not a competition between the two approaches. It is an understanding of which tool fits which moment. A student who can cognitively engage with what they’re experiencing has access to both. A student who is overwhelmed, flooded, or deeply fatigued may only have reliable access to one. The body is always available. The thinking mind is not always online.

As yoga teachers, this gives us something important to work with. We are, by the nature of what we teach, bottom-up practitioners. Every cue, every pose, every breath instruction is an invitation into afferent territory.

What This Means in the Yoga Room

Cues that invite internal sensation are not merely poetic or atmospheric. “Feel the weight of your body against the floor.” “Notice where your breath is moving.” “Sense the length of your exhale.” These cues are intentional invitations into afferent territory. When we build them into our sequencing deliberately, we are doing something specific: we are directing a student’s attention toward what the body is already reporting upward, and away from the brain’s top-down narrative.

We can do this with more than language. The arc of a practice itself, how we warm the body, how we build and then release, how we arrive in stillness, is a sequence of afferent inputs we are actively curating. Every transition, every sustained hold, every conscious breath instruction contributes to the stream of signals the body is sending upward. We are not just hoping something shifts. We are creating the conditions for it.

By the time a student arrives in savasana, the accumulated afferent input of the entire practice has been quietly updating the nervous system’s read of the situation. The brain, receiving that updated report, shifts its response. The student who arrived wound tight and leaves somewhere softer hasn’t just had a nice stretch. Their body has been in conversation with their brain for the entire practice. And we helped shape what that conversation said.

Giving the Body the Floor

We are bottom-up practitioners. That is not a limitation. It is a precision. When we sequence with intention, when we cue sensation over performance, when we offer hands-on guidance that is consensual, skilled, and well-timed, we are working directly with the afferent system. We are giving the body something worth reporting. And the research gives us reason to trust that the brain is listening.

The somatic and body-based frameworks developed by Stephen Porges, Bessel van der Kolk, and Peter Levine, the same polyvagal-informed lineage we explored in an earlier essay, all converge on the same finding: the body is a primary and reliable pathway into nervous system regulation. Van der Kolk specifically identified yoga as a practice that works through exactly this mechanism, using body-based input to increase the felt sense of safety from the inside out. And the research on yogic breathwork confirms what we can observe in any well-held class: slow, conscious breathing measurably shifts autonomic balance toward greater parasympathetic activation, increasing heart rate variability, and reducing the physiological markers of chronic stress. The body sends the signal. The brain updates its assessment. The mental and emotional state shifts.

Perhaps the most quietly radical thing this essay offers is permission. Permission to trust what you feel before you can explain it. The heart was never just a symbol. It has always been in active conversation with the brain, and it seems, always been leading that conversation. The body has always known things the thinking mind was still catching up to.

For yoga teachers, this is the gift inside the science: every time you invite a student to feel rather than figure out, you are giving the body the floor. And the body, it turns out, has quite a lot worth saying.

This is the eighth essay in a foundational series on nervous system literacy for yoga teachers. Start from the beginning with essay one, or subscribe to follow along — one final foundational essay remains.

HRV gets mentioned constantly and explained…well...almost never. Or at least not in a way that’s fully comprehensible or genuinely useful, in daily life, or in the yoga classroom. But that’s the aim here: what is HRV, why does it matter, what do I actually do with it, and of course, how does it relate to yoga?

Let’s start from the beginning.

Your Heart Doesn’t Beat Like a Metronome

Most people assume a healthy heart beats with perfect, steady regularity: tick, tick, tick, like a clock. In fact, the opposite is true. A healthy heart beats with subtle, continuous variation in the time between each beat. Sometimes 0.9 seconds between beats. Sometimes 1.1. Sometimes 0.85. That variation isn’t a flaw. It’s a sign that the nervous system is alive, responsive, and doing its job.

Heart rate variability is simply the measurement of that variation; the millisecond differences in time between consecutive heartbeats, tracked over a defined period.

That’s the simple version. To understand what’s actually creating that variation, it helps to picture what’s happening underneath it.

The Gas and the Brake

Think of the two branches of the autonomic nervous system as the gas pedal and the brake of a car. To drive safely, you need both, and you need them working back and forth, responding to the road in real time. Press the gas to accelerate, ease onto the brake to slow down, press the gas again. That constant, responsive interplay is what keeps you in control.

The sympathetic branch is the gas. The parasympathetic branch is the brake. And like good driving, neither is meant to stay fully engaged — they’re designed to hand off to each other, moment to moment, in a continuous back-and-forth.

Now imagine someone holds the gas pedal to the floor. You can still tap the brake, but with the engine running that hard, it barely makes a dent. You’re not driving safely. You’re definitely not driving smoothly. Nobody wants to be in that car.

That’s low HRV. The gas is dominant, the brake can’t get much purchase, and as a result, the heart has less moderating influence and the beats become more uniform, more similar interval after interval, because there isn’t enough of the parasympathetic, slowing influence to create meaningful variation between them.

High HRV is the smooth driver: gas, brake, gas, brake, responsive to every shift in the road. That back-and-forth is exactly what healthy beat-to-beat variation looks like. Not inconsistency. Both branches online, talking to each other, doing exactly what they were designed to do.

What’s Actually Driving the Brake

Here’s where the anatomy connects back to what I’ve covered earlier in this series.

The parasympathetic branch operates primarily through the vagus nerve, and its primary chemical messenger is acetylcholine. Where the sympathetic branch communicates through hormones that travel relatively slowly through the bloodstream, the vagus nerve acts fast — within a single heartbeat — using acetylcholine to apply that slowing, moderating influence directly to the heart in real time.

This means the beat-to-beat variation in your heart rate is being driven largely by vagal activity. When parasympathetic tone is robust, the vagus nerve is actively moderating each beat, introducing variation as it responds to tiny fluctuations in breath, posture, and internal state. When sympathetic dominance increases, vagal input decreases and, as a result, the heart has less moderating influence. The beats become more uniform. The variability shrinks.

HRV is, in this sense, a window into how much parasympathetic influence is present in the system at any given time and something we’d otherwise have no direct way to measure, but that we can observe through the activity of the heart. Generally speaking, higher HRV reflects greater parasympathetic influence; lower HRV reflects less.

Breath is one of the most immediate ways to see this in action. When you inhale, the diaphragm descends, pressure in the chest shifts, and the heart very slightly speeds up. When you exhale, the opposite, pressure shifts back, the heart very slightly slows. This is called respiratory sinus arrhythmia, and it’s one of the primary contributors to HRV. A longer exhale means more time for the vagus nerve to deliver its acetylcholine-mediated slowing effect so there’s more variation, more parasympathetic input, more of the brake doing its job. This is the physiological basis for something you may have been cueing intuitively: that an extended exhale feels calming in a way that’s distinct from simply breathing slowly. You were right. It’s the brake getting more purchase, beat by beat.

Why Your Number Isn’t My Number

Here’s where HRV gets considerably more complicated and where most wellness conversations quietly fall apart.

Someone’s HRV range — their baseline — is shaped by an enormous range of factors, many of which have nothing to do with how stressed or recovered they feel on any given day. Biological sex. Age. Hormonal status. Genetics. A history of chronic illness or prolonged stress. Whether they’re navigating a hormonal transition. Whether they’ve maintained a consistent meditation practice for a decade or just started doing yin yoga twice a week. Whether they’ve been practicing pranayama for years or are brand new to intentional breathwork. All of it leaves a mark. And some of it leaves a permanent one.

My husband and I are close in age, live in the same house, share a fairly similar lifestyle, and sleep in the same bed. His HRV regularly climbs up to 150 when he sleeps. Mine, after improving significantly over the past year, sits around 28 on a good night. For context: my baseline for years since tracking on a wearable sat between 4 and 8. A result, I believe, of decades of complex PTSD, which research suggests can significantly suppress baseline HRV through chronic dysregulation of the autonomic nervous system. Same household, same lifestyle. Wildly different nervous systems.

This is exactly why your number is yours alone — and why the wellness industry’s habit of treating HRV like a performance score to optimize misses the point almost entirely. So much of what shapes your baseline is simply outside your control.

That said, some things within your influence do appear to matter. Research suggests that regular yoga practice, consistent pranayama, and meditation practiced over weeks and months are associated with improved parasympathetic tone and upward trends in HRV. A 2016 systematic review of 59 studies found that yoga can positively influence cardiac autonomic regulation, with regular practitioners showing higher resting vagal tone than non-practitioners. Studies on pranayama — including Bhramari and Nadi Shodhana — have shown improvements in parasympathetic HRV parameters after six months of consistent practice. Aerobic fitness, quality sleep, and bottom-up regulation practices of all kinds point in a similar direction.

It’s also worth noting that not all physically demanding yoga is the same to the nervous system. A heated vinyasa class, for example, may acutely drop your HRV during and immediately after the session because heat is a physical stressor and the sympathetic system responds accordingly, much the same way it would to vigorous exercise. This doesn’t mean heated yoga is harmful; research on regular heat exposure suggests the nervous system can adapt and build resilience over time. But if you practice in a heated environment and notice your HRV dips the following morning, that’s not a mystery. That’s your nervous system accurately reporting that it worked hard and is in recovery. The same applies to any physically demanding class, a new practice format your body is still adapting to, or simply several consecutive days of practice when your system needed rest.

None of this means these practices are harmful. The research points toward consistent engagement with all of them as supportive of nervous system resilience over time. What it does mean is that HRV isn’t a number you can target and move through willpower or the right protocol. What you can influence, over time, is the trend of your unique baseline range. Practices that build stress resilience and nervous system flexibility can trend it upward. Accumulated load, inadequate recovery, ongoing stressors, and physiological factors outside your control can trend it downward. Understanding which influences are present at any given time is most of what makes the number meaningful.

Working With Your Unique Baseline

Here’s what actually makes HRV useful: learning your range.

Not a number. A range. Because day-to-day fluctuation is entirely normal. HRV will naturally vary from one morning to the next as a reflection of ordinary biological variation, not crisis. What matters is meaningful deviation from a personal trend over time, on a single device, tracked consistently.

Once you have enough data to recognize that range, the fluctuations start to speak. And this is where HRV becomes something genuinely practical: not a score to improve, but a signal to learn from. Think of it as the nervous system having a direct line to communicate — one that doesn’t require pain or exhaustion to get your attention.

Three hard training days in a row and your HRV drops meaningfully below its usual range — that’s the nervous system suggesting a rest day before the body has to say it louder. Seven days of regular practice and your HRV is holding steady or climbing — that’s affirmation that the load is within current capacity and the training is landing. Life seems fine on paper but HRV has been quietly below range for two weeks — that might be worth getting curious about. Is there stress that hasn’t been fully registered? A hormonal shift? An accumulation of load that hasn’t surfaced consciously yet?

This is where HRV can become a tool for tailoring a wellness approach to actual physiology, not someone else’s protocol. The yoga regimen claiming to work for everyone on your social feed might genuinely not work for your nervous system. Your HRV trend over time is one way to get honest feedback on that. Is the practice supporting recovery and resilience, or quietly adding to the load? The number can’t answer that question definitively, but it can point toward better questions.

In my own experience, this kind of pattern recognition has been one of the more valuable things HRV offers. Not a diagnosis, not a prescription, but a prompt to pay attention to. A reason to ask what might be present that I haven’t fully noticed yet, and to respond before the body has to communicate through something harder to ignore.

And when the number is low and there’s no immediate explanation, the system may be responding to something that hasn’t fully registered consciously yet. Maybe it’s worth getting curious about what your nervous system is trying to communicate.

What This Means in the Yoga Room

For yoga teachers, understanding HRV reframes something important about what you’re already offering.

The practices that support vagal tone and nervous system resilience show up everywhere in a well-sequenced class. Extended exhales. Ujjayi breathing, that gentle glottal constriction that may contribute to parasympathetic regulation through slow, controlled respiration and vibration of structures innervated by the vagus nerve. Coherent, intentional pranayama that approximates the five-to-six breath-per-minute resonance research consistently associates with increased vagal tone. Mantra and humming, which create vibration in structures the vagus nerve innervates. Sequencing that builds activation and then genuinely guides the system back down, not just physically but neurologically. Sustained stillness in long holds or supported postures. Savasana that is unhurried and real.

These aren’t aesthetic choices. They are inputs into the system. Research on yoga and autonomic regulation — while still evolving and not without limitations — consistently points toward practices that move the nervous system through activation and genuine recovery, practiced repeatedly over time, as supporting the flexibility that HRV reflects. Intentional sequencing that honors this arc isn’t just good teaching. It’s nervous system tending.

Your students may never track their HRV. Most of them won’t. But understanding this framework gives you more precision and more confidence about why what you’re offering does have a measurable impact on the nervous system. You’re not adjusting a number. You’re contributing, class by class, to the conditions that support the nervous system’s capacity to regulate itself which, for those who are tracking, might just be something they can see reflected in their HRV over time.

A Note on Tracking

If you do wear a wearable and want to use it meaningfully, a few things worth knowing.

HRV declines across the lifespan in both sexes. This is normal physiology, not failure. Hormonal transitions can shift your baseline meaningfully in ways unrelated to stress or recovery. If your number changes significantly during a period of hormonal change, that points to your nervous system accurately reflecting real physiological load.

There is no universal good number. Given everything discussed above, your trend over time, on a single device, is the only comparison worth making. Day-to-day variation is normal. Research on HRV tracking in athletes suggests that day-to-day fluctuation of roughly 3 to 13% within a personal range can be considered ordinary biological noise rather than a meaningful signal. A small shift from one morning to the next, in other words, is not news. A sustained departure from your personal range over several days or weeks is worth paying attention to.

Consumer wearables measure HRV differently — different algorithms, different measurement windows — so scores across devices aren’t comparable. The clinical gold standard is an electrocardiogram. Consumer devices use a light-based sensor that is less precise but increasingly well-validated for tracking personal trends. Consistency of device and timing of measurement matter more than the precision of any single reading.

The Deeper Point

HRV is one of the novel ways technology has given the nervous system a voice; a non-invasive signal that communicates what’s happening inside the system without requiring pain or exhaustion to get your attention.

Learn your range. Notice what moves the number. Use the dips as invitations to rest, reflect, or reconsider. Use the climbs as confirmation that the work is landing. And when the number drops and there’s no immediate explanation, the system may be responding to something that hasn’t fully registered consciously yet. These signals are messages about the state of the nervous system, which governs everything. There’s valuable information there, if you’re willing to listen.

That same principle extends into the yoga room. The practices you’re offering your students — from the sequence of the asana itself to the added tools like breathwork, meditation or consensual hands-on teaching — are exactly the conditions that support what HRV reflects. Research points toward consistent engagement with these practices, over time, as supportive of the nervous system flexibility HRV mirrors. Your students may never track their numbers. But you can understand, with more precision than before, why what you’re offering matters and bring that understanding into how you teach. You’ve known intuitively that this work does something real. Now you have a little more language for how.

In the next post, we go deeper into how the mind and body actually communicate — and explore the quietly radical finding that in this conversation, the body is doing most of the talking. After that, the foundational series closes with a post on the stress continuum: what stress actually is, why it isn’t the enemy, and what it means for every nervous system in your classroom.

This is the seventh 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.

The gas and brake analogy in this post actually comes from my book — where I go considerably deeper into how anatomy-based, consent-centered touch works as a bottom-up regulatory tool and what that means for HRV. If any of this sparked your curiosity, Hands-On Yoga Assists: A Teacher's Guide to the Rubber Band Method® is a good next step.

Polyvagal theory takes that nuance several steps further.

Developed by neuroscientist Stephen Porges in the 1990s, polyvagal theory proposes that the autonomic nervous system, and the vagus nerve in particular, operates not in two states but in three, organized in a hierarchy that reflects the evolutionary history of the nervous system itself. It has become a highly influential framework in trauma therapy, somatic practice, and increasingly, yoga teaching.

It has also generated genuine scientific debate, which we’ll touch on honestly. But as a clinical and pedagogical map, a way of understanding what you’re seeing in your students and what your classroom environment is actually doing, it is remarkably useful.

Two Vagal Pathways, Not One

Here is the core anatomical proposition of polyvagal theory, and the place where it meaningfully extends what we covered in the last post.

The vagus nerve is not a single, uniform pathway. It has two distinct branches, and according to Porges, they serve different functions and are activated under different conditions.

These two pathways are the ventral vagal complex and the dorsal vagal complex.

The ventral vagal complex is the newer, more evolutionarily recent branch. It originates in a specific region of the brainstem called the nucleus ambiguus and innervates the face, eyes, ears, larynx, and pharynx, including the muscles of facial expression, the middle ear, and the voice. It also connects to the heart and lungs. This is the branch associated with social engagement, connection, and felt safety. When it is online, the face is expressive, the voice has warmth and prosody, the eyes make contact, and the middle ear is tuned to the frequency range of human speech. The body is signaling and receiving the signal that the environment is safe.

The dorsal vagal complex is the older, more ancient branch. It originates in the dorsal motor nucleus of the vagus and descends primarily to the organs below the diaphragm, including the digestive tract, the heart at a deeper level, and the viscera. In its healthy, regulated expression, the dorsal vagal supports digestion, rest, and restoration. But under conditions of extreme or inescapable threat, it is the branch associated with the freeze response, the profound shutdown, immobilization, dissociation, or collapse we described in earlier posts. This is an ancient survival strategy, one that predates mammals: play dead, conserve resources, disappear. It is involuntary, it is not weakness, and it is important that yoga teachers understand it as a protective response rather than a behavioral choice.

The Three-State Hierarchy

Polyvagal theory organizes these pathways, along with the sympathetic branch, into a three-state hierarchy that the nervous system moves through in a predictable order based on its assessment of safety and threat.

At the top of the hierarchy is the ventral vagal state: social engagement, connection, regulated arousal. This is the state in which learning, creativity, intimacy, play, and genuine rest are all possible. It is not the absence of activation. You can be energized, focused, even challenged and still be operating from ventral vagal regulation. What characterizes it is the felt sense of safety and connection. This is the state most conducive to a meaningful yoga practice, and the state a well-held class can help cultivate.

When the nervous system determines that the environment is not safe, that a demand or threat is present and must be met, it moves down the hierarchy to sympathetic mobilization: fight or flight. Resources are redirected, the body prepares to act, and social engagement becomes secondary to survival. As we explored in the sympathetic branch post, this is not inherently pathological. Challenge, intensity, and even productive stress live here. The question is always whether the system can return to ventral vagal regulation once the demand has passed.

When the nervous system detects overwhelming or unresolved threat, especially when mobilization does not restore a sense of safety, it may shift toward dorsal vagal states of shutdown: freeze, collapse, dissociation, or immobilization. These responses reflect a move toward energy conservation and protection rather than active defense. In polyvagal theory, this state is often described as the most evolutionarily ancient pattern of response, emerging when the system no longer organizes primarily around fighting or fleeing.

This hierarchy is often described in polyvagal theory as the autonomic ladder. Regulation tends to move the system toward ventral vagal states of safety and connection, while dysregulation can shift the system toward sympathetic mobilization or dorsal withdrawal. In practice, the nervous system usually moves through these states gradually rather than instantly, which means that deep parasympathetic rest is often difficult to access when sympathetic activation is still high. You cannot simply will yourself into savasana from a threat state. The body typically needs time and supportive conditions to settle.

The Nervous System Is Always Listening

Here is something worth sitting with as a yoga teacher: your students’ nervous systems are making assessments about safety and threat constantly, almost entirely below the level of conscious awareness.

Porges gave this process a name: neuroception. It is the nervous system’s continuous, subconscious scanning of the environment for cues of safety or danger, reading facial expressions, voices, posture, proximity, and touch before the thinking brain has weighed in at all. We’ll explore neuroception in much greater depth in a future post, but it’s worth introducing here because it reframes something important about what happens in a yoga room.

According to the World Health Organization (WHO), around 70% of people globally will experience a potentially traumatic event during their lifetime. Not all of those people will develop PTSD or a clinical trauma response, but many will carry nervous systems that have been shaped by those experiences in ways that affect how safety is perceived, how touch is received, and how the body responds to a room full of strangers being asked to close their eyes and be still.

This is not cause for alarm. It is cause for awareness. Your students are not fragile, and your classroom is not a minefield. But the more you understand that a nervous system reading threat will respond from a very different place than one reading safety, the more intentional you can become about the environment you create before you’ve said a single word of instruction.

What This Looks Like in a Yoga Room

Think about what happens when a student walks into a yoga studio for the first time. Their nervous system is scanning, before their conscious mind has processed a single thought, for signals of safety or threat. Is the teacher’s voice warm or flat? Do people make eye contact or look through me? Does the room feel welcoming or evaluative?

These are not trivial aesthetic preferences. They are neurological inputs, processed in large part through the ventral vagal system, the ears tuned to vocal prosody, the eyes reading faces, and the body reading the social temperature of the room.

This is why the way you speak to your students matters at a level far deeper than content. A warm, regulated, melodic voice, the same quality Porges observed in mothers soothing infants, which he identified as a primary ventral vagal activator, literally helps move a student’s nervous system toward the state in which they can learn, integrate, and be present. A flat, clipped, or overly performance-focused delivery can do the opposite, even when the words themselves are perfectly correct.

It’s also why the arc of a well-structured class matters neurologically, not just aesthetically. Moving from dynamic activation into genuine stillness is not just good sequencing. It can help support a shift up the autonomic ladder, from sympathetic mobilization back toward ventral vagal regulation. Savasana at the end of that arc is not an add-on. It is the integration. It is where the nervous system consolidates the shift.

An Honest Note on the Science

Polyvagal theory is influential, clinically resonant, and widely applied, but it is not without its critics. Some neuroscientists have challenged aspects of Porges’ neuroanatomical claims, particularly around the strict separation of the ventral and dorsal vagal pathways and the proposed evolutionary timeline. The debate is ongoing and worth knowing about, especially as the theory continues to proliferate in wellness and therapeutic spaces, sometimes without that nuance.

What this means practically: polyvagal theory is best held as a map, not a complete and final territory. Maps are useful precisely because they simplify complex terrain into navigable form. This one has helped thousands of clinicians, somatic practitioners, and yoga teachers better understand what they were already observing in the bodies in front of them. That practical utility is real, even as the underlying science continues to be refined.

As yoga teachers, we are never diagnosing or treating. However, yoga is open to all, and that means we will encounter individuals at different places on the autonomic ladder, often without knowing it. Recognizing the cues creates space for compassion rather than judgment. We are using an understanding of the nervous system to inform how we hold space, how we speak, how we sequence, how we prioritize consent and offer touch. For that purpose, polyvagal theory offers a genuinely useful lens.

The Map Worth Carrying

The vagus nerve is not a single pathway but a layered system, and the states it mediates, social engagement, sympathetic mobilization, and dorsal vagal shutdown, form a hierarchy that the nervous system moves through in response to its assessment of safety and threat. Understanding this hierarchy doesn’t just change how you think about stress and relaxation. It changes how you think about your voice, your room, and the student in front of you who can’t quite seem to arrive.

In a future post, we’ll touch on neuroception—Porges’ term for the nervous system’s unconscious scanning for safety and threat. It’s present in every classroom, with every student, in every moment of every class. You’re already navigating it. Understanding it just makes you more intentional about how.

This is the fifth 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.

For teachers who incorporate touch, consent is the foundation. Learn how to approach it with clarity and confidence, and gain 16 foundational assist techniques inside the Rubber Band Method® Foundations course. 30 CEU hours available.

It’s a seductive framing. It’s also incomplete and, in some ways, just as misleading as calling the sympathetic nervous system the villain. In reality, sympathetic activation is not inherently stressful. It is the system that allows you to move, respond, and engage with your environment. In a yoga class, it supports your ability to move through vinyasas, transition between shapes like downward dog and warrior poses, and even come back to standing after savasana.

The parasympathetic nervous system is not the hero of this story. It is the moderator. Understanding the difference matters enormously for how you think about your students, your sequencing, and what you’re actually trying to cultivate in a yoga room.

The Architecture of the Parasympathetic Branch

Where the sympathetic nervous system originates in the thoracic and lumbar spine (the middle and lower back), the parasympathetic branch has two distinct points of origin: the brainstem and the sacrum (the triangular bone at the base of the spine, just above the tailbone).

From the brainstem, several cranial nerves carry parasympathetic fibers out to the head, neck, and organs of the chest and abdomen. The most significant of these, by a considerable margin, is the vagus nerve.

The word vagus is Latin for wandering, and the name is apt. The vagus nerve is the longest cranial nerve in the body. It exits the brainstem and passes through the neck alongside the carotid artery and jugular vein. Along the way, it innervates the ears and the throat, including the glottis, the part of the larynx that houses the vocal cords.

This is not a minor anatomical footnote. The vagus nerve innervates structures involved in vocalization and sensation in parts of the outer ear, which helps explain why a calm, warm voice can feel regulating and why humming, chanting or using ujjayi breathing may support parasympathetic activity. The sound environment you create in your classroom may be doing more nervous system work than you realized.

From the neck, the vagus continues its descent through the chest, branching extensively through the heart, lungs, and esophagus, before reaching the stomach, liver, pancreas, gallbladder, and intestines. It wanders, it branches, it listens, and it speaks, carrying information both from the body to the brain and from the brain to the body. We’ll explore that two-way conversation in depth in a future post.

From the sacrum, a second set of parasympathetic fibers extends downward to serve the lower digestive tract, bladder, and reproductive organs. These fibers govern the functions of elimination and, in states of genuine safety, sexual arousal and intimacy.

Acetylcholine: The Parasympathetic Messenger

Where the sympathetic nervous system communicates primarily through epinephrine and norepinephrine, the parasympathetic branch operates through a different neurochemical entirely: acetylcholine (ACh).

Acetylcholine is one of the oldest neurotransmitters in evolutionary terms. It predates the vertebrate nervous system and is found across a remarkable range of species. In the context of the parasympathetic branch, it acts as a broad moderating signal, modulating the systems that sympathetic activation has mobilized (including everyday actions, not just stress responses).

At the heart, acetylcholine slows the heart rate and reduces the force of contraction. This is the direct counterbalance to epinephrine’s acceleration. This is also the neurochemical basis of the slowdown you feel after a vigorous practice begins to wind down, or during a long, slow exhale. The vagus nerve’s influence on heart rate is so direct and measurable that it forms the basis of heart rate variability (HRV), a commonly used noninvasive marker of cardiac vagal regulation that we’ll explore in a future post.

In the brain, acetylcholine plays a central role in attention, learning, and memory consolidation. Parasympathetic states, meaning genuine rest and not just physical stillness, support the kind of diffuse, integrative cognition that allows new information to settle and connect. This is one reason insights often arrive in the shower, on a walk, or in savasana. The brain in a parasympathetically supported state is doing different and equally important work than the brain under sympathetic load.

In the digestive system, acetylcholine stimulates the entire process. It increases saliva production and activates gastric secretions, shifting the body back toward digestion after periods of activation, when resources were directed elsewhere to support mobilization.

This matters more than it might initially seem because the gut is not merely a digestive organ. It is home to the enteric nervous system (often referred to as the “second brain”) and produces the vast majority of the body’s serotonin.

Serotonin is commonly associated with mood and the brain, but approximately 90–95% of it is actually found in the gut, where it helps regulate intestinal movement and contributes to gut–brain signaling. This is one reason the gut is so central to nervous system health. Chronic stress can disrupt both digestion and this signaling pathway, influencing not only how the gut functions, but how we feel.

When the parasympathetic branch is chronically undertoned—when the body does not spend enough time in a well-perfused, digestive state—both serotonin activity and gut–brain communication can be affected. This is one of the more underappreciated ways chronic stress influences mood. It is not only a brain chemistry story; it is also a gut–brain story.

This relationship is reflected clinically. Medications that influence serotonin signaling are often prescribed for conditions like irritable bowel syndrome, highlighting the bidirectional nature of the gut–mood connection.

Parasympathetic Dominance: The Other Extreme

Here is where the wellness narrative around the parasympathetic branch tends to go quietly off the rails.

In a culture saturated with chronic stress, the parasympathetic branch is often framed as the destination, as though more is always better. But the nervous system does not work that way. Acute excessive vagal activation can create problems, including sudden drops in heart rate and blood pressure, as in vasovagal fainting. Some low-arousal or shutdown states can also look less like restoration and more like collapse. So while underactive parasympathetic regulation is common in modern life, parasympathetic activity itself is not inherently synonymous with health.

Acute excessive vagal activation, and certain low-arousal or shutdown states, can produce their own set of significant problems. Heart rate becomes too low. Blood pressure drops. Digestion becomes dysregulated in a different way, including dysmotility, bloating, and nausea. Fatigue can become profound and unresponsive to rest. Cognitive function may dull. Motivation and engagement can flatten. In acute form, excessive vagal activation produces the freeze and faint responses we described in the first post. This is the sudden parasympathetic override that drops heart rate and blood pressure dramatically, sometimes causing loss of consciousness.

At the extreme end of chronic parasympathetic dominance, what emerges looks less like relaxation and more like shutdown. This includes flat affect, profound fatigue, social withdrawal, and emotional numbness that can characterize certain presentations of trauma, depression, and chronic illness. This is a nervous system that has been pulled so far toward the brake that it can no longer find the accelerator.

No one would choose this state. It is a useful corrective to the idea that the parasympathetic branch is inherently the healthy one. Both branches are essential. Both require tone, responsiveness, and flexibility. The goal, as we established in the first post, is not calm. It is flexibility: the capacity to move fluidly between activation and recovery, mobilization and rest, engagement and ease.

The Undertoned Branch in an Overtaxed World

That said, there is an honest asymmetry worth naming.

We live in an environment of near-constant sympathetic provocation. Artificial light disrupts the diurnal cortisol curve. Screens deliver stimulating input at every idle moment. News cycles generate ambient threats. Work bleeds into evenings and weekends. Social comparison is built into the platforms most people spend hours on daily. The body rarely receives an unambiguous signal that it is genuinely safe, that demands have paused, and that it can fully release vigilance.

In this context, while neither branch is inherently superior, it is the parasympathetic branch that most commonly suffers from underuse. Not because relaxation is virtuous, but because the conditions that allow for genuine parasympathetic activation are increasingly rare in modern life. These conditions include felt safety, reduced input, rhythmic movement, connected relationship, and unhurried time.

This is why practices that support parasympathetic tone matter. Extended exhales activate the vagus nerve directly, slowing the heart through acetylcholine release. Humming, chanting, ujjayi breathing, and vocalization stimulate the vagal branches that innervate the larynx and glottis. Slow, rhythmic movement supports the transition between sympathetic mobilization and parasympathetic recovery. Skillful, purposeful touch, when it is consented to and received as safe, can signal to the nervous system that the environment is not threatening and support a downregulation that cognitive reassurance alone often cannot produce.

Your yoga class, when structured well, is an environment that helps tone and strengthen the parasympathetic branch. Not because it eliminates sympathetic activation, but because it moves through activation and back to recovery in a way modern life rarely structures. This is why we always allot time for savasana and cool down. That time at the end of class is not a reward for the hard work. It is the neurological point of the whole thing.

The Takeaway

The parasympathetic nervous system is vast, chemically rich, and critically important, not as a destination to reach, but as a dynamic counterpart to the sympathetic branch. Its primary messenger, acetylcholine, moderates the heart, supports cognition, restores digestion, and enables the gut conditions that underpin serotonin production and mood regulation. Its primary vehicle, the vagus nerve, is one of the most significant structures in the body for understanding why yoga, breath, sound, and touch produce the effects they do.

Neither branch is the hero. Both branches, working in flexible, responsive balance, are the point.

In the next post, we’ll expand this framework through the lens of polyvagal theory, Stephen Porges’ influential work that takes the vagus nerve as its centerpiece and offers a more nuanced map of how the nervous system navigates safety, threat, and connection. It’s a framework that has quietly reshaped trauma therapy, somatic practice, and yoga pedagogy alike, and it deserves a careful, honest look.

This is the fourth 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.

Explore: Hands-On Yoga Assists: A Teacher’s Guide to the Rubber Band Method®, which begins with The Science of Safe Touch and builds into practical, anatomically informed assists you can use in your classes.

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.