There's a moment most teachers know well, somewhere around period four, when you notice your own voice has gone a little sharper than you meant it to. Not angry, exactly — just wound a notch tighter than the situation actually calls for. You catch it, you soften, you keep teaching. Nobody else probably noticed. But your body did. Long before you consciously register "I'm stressed," your nervous system has already shifted gear.
That's the thing about the nervous system: it keeps its own records - including in the body, whether or not we're paying attention. This week I came across a study that actually opened those records up not by asking people how stressed they felt, but by measuring, directly and in real time, what their body was doing while they breathed.
I think about this distinction often in my own work. In my current study with twelve teaching staff at a Gold Coast school, I measure both perceived stress and HRV data before and after each session using the HeartMath Inner Balance Coherence Plus device, specifically because self-report alone has never told the whole story. Teachers are often remarkably good at describing their stress in words well after their body has already moved through several rounds of it. What's been missing from so much of the wellbeing literature is anyone actually watching the physiology move while the intervention is happening, rather than just before and after.
So it mattered to me to see a new study, published this year, that did exactly that. Researchers put 27 healthy adults through a randomised crossover trial and tracked their skin sympathetic nerve activity ehich is a more direct, more sensitive window into the "fight or flight" branch of the nervous system than heart rate variability alone — while each person did a single fifteen-minute session of slow, paced resonance breathing (Liu et al., 2025). What they found was exactly the pattern you'd want to see, and exactly the pattern my own participants describe anecdotally but rarely get measured this precisely: a brief uptick in that alert signal during the breathing itself, followed by a clear, measurable settling into a calmer, more flexible state once the session ended — including a real rise in vagally-mediated HRV during recovery.
Here's the part I find genuinely interesting, mechanistically. Heart rate variability isn't really about your heart rate being high or low — it's about how much it varies, moment to moment, in response to your breath and your emotional state. A rigid, unvarying heart rhythm is a nervous system stuck in one gear. This study gives us a second, independent line of evidence. Sympathetic nerve activity itself, not just doesn't just quiet the nervous system, it widens its range, letting it move between alert and calm more easily, the way it's actually designed to. Think of it less like a dimmer switch and more like retuning an instrument.
None of this requires an app, a classroom overhaul, or twenty minutes you don't have. Try this before your next tricky lesson or meeting: sit for a moment, breathe in for a count of four, and out for a count of six, for six full breaths — roughly a minute, maybe two. Nothing more complicated than that. If you happen to have a hand free, rest it lightly over your heart while you do it; it tends to help attention settle there. You're not trying to switch off how you feel. You're just giving your nervous system a chance to widen back out before you walk back into the room.
I started this research because I kept watching capable, caring teachers run themselves down to a flat line, long before anyone, including them, noticed it was happening. A fifteen-minute lab study won't fix that on its own. But every time the evidence grows a little more precise, a little more physiological, it gets a bit harder to wave the whole thing off as "self-care." It's regulation. It's measurable, down to the level of individual nerve signals. And it's available to you in less time than it took to read this.
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Steve Carter is a Teacher Wellbeing Officer and PhD researcher at Bond University, Gold Coast. His research examines the impact of heart coherence practices on stress and nervous system regulation in teachers.
