The internet’s most quoted nerve
„You just need to activate your vagus nerve.“ – „My nervous system is dysregulated.“ – „A cold shower resets your system.“
Few concepts have spread as fast in recent years as polyvagal theory. It supplies the vocabulary for countless reels, coaching sessions and self-help books: ventral, sympathetic, dorsal – safety, fight or flight, freeze. And then, in spring 2026, a publication appeared that shook the whole thing. High time for a sober look.
What the theory says
The psychophysiologist Stephen Porges introduced polyvagal theory in 1994. In brief: in mammals, the vagus nerve is said to have two branches with opposing functions. The newer «ventral» branch stands for social connection and safety, the older «dorsal» one for freezing and withdrawal. Between them sits the sympathetic system for fight and flight. Unconsciously, the body is said to check continuously whether the situation is safe – Porges calls this «neuroception».
It’s easy to see why this landed so well. The theory explains in simple images why you can’t think clearly in a conflict, why some people don’t explode under strain but shut down inside, and why calming down often works better through the body than through arguments. It gives bodily states a name – and names bring relief.
What happened in 2026
In 2026, 39 internationally recognised experts in the physiology and evolution of the vagus nerve and in vertebrate social behaviour published a joint evaluation in the journal Clinical Neuropsychiatry (volume 23, issue 1, pages 100–112). The title leaves little room for interpretation: polyvagal theory is untenable, because it cannot be defended on the basis of existing neurophysiological and evolutionary evidence. The paper builds on a detailed critique by Paul Grossman published in Biological Psychology in 2023.
The three core points:
- The evolutionary story doesn’t hold. The claim that the «ventral» vagal branch is a mammalian achievement does not stand up to comparative anatomy.
- The anatomical separation is not as clean as the theory requires. Control of heart rate runs almost exclusively through the nucleus ambiguus; the dorsal nucleus is denied the role attributed to it.
- The measure doesn’t carry. Respiratory sinus arrhythmia – the variation in heart rate with the breathing rhythm – is treated in the theory as a window onto «vagal tone». Across different physiological states, however, it is not a reliable indicator of that.
In fairness: Porges disagrees, and there are voices arguing that the theory has not been «debunked» but is simply part of a normal scientific dispute. That is true. But when 39 experts from precisely the disciplines the theory draws its authority from object as one, the burden of proof no longer sits with the critics.
And what does that mean for the exercises?
Here comes the decisive point, and it is good news: a wrong explanation does not make an effective exercise ineffective.
That slow breathing calms you down has been known for longer than polyvagal theory has existed. And the evidence for it is respectable:
- A meta-analysis by Goessl, Curtiss and Hofmann (2017, Psychological Medicine) of 24 studies on heart rate variability biofeedback found clear effects on stress and anxiety (Hedges’ g ≈ 0.8).
- Meta-analyses on depressive symptoms find medium effects in the region of g ≈ 0.4.
- That voluntarily slowed breathing measurably increases heart rate variability has also been confirmed meta-analytically (Laborde and colleagues, 2022).
On top of that come methods with their own independent evidence base: progressive muscle relaxation, the body scan, mindfulness-based stress reduction. All three work without requiring belief in ventral and dorsal vagal branches. You’ll find introductions in Finding inner calm with PMR, Body scan for beginners and Mindfulness vs. meditation.
Where I would be careful
- «Vagal tone» from a smartwatch. HRV readings from consumer devices fluctuate with sleep, caffeine, exercise, alcohol and measurement position. As a rough trend over weeks they are interesting; as a daily verdict on your inner state they are not.
- Vagus hacks. Ice water, humming, gargling, cold showers: there are indications that cold exposure and slow exhalation do something to the autonomic nervous system in the short term. That is not a «system reset», and the evidence for the popular variants is thin.
- Self-diagnosing a «dysregulated nervous system». The phrase sounds medical but is not a diagnosis. It can delay a proper assessment – of the thyroid, sleep apnoea, iron deficiency, depression, an anxiety disorder.
- Trauma work built exclusively on this theory. For context on the term itself, see The history of the term trauma.
Why the explanation matters at all
You could argue that if the exercise helps, the story behind it is irrelevant. I see it differently, for a practical reason.
Explanations determine what you blame when something doesn’t work. Someone who believes their nervous system is broken looks for the solution in repairing a defect – and experiences every setback as proof of being more damaged than they thought. Someone who knows that tension is a normal, trainable response simply keeps practising.
Psychology has been through cycles like this before. Power posing is the best-known example of an idea that went viral and only partly survived scrutiny – you can read about it in What is power posing?.
🟢 Tip: If you want an exercise that works today and will still work tomorrow: extended exhalation. Four seconds in, six to eight seconds out, for two to three minutes. No theory required, well evidenced, possible anywhere.
Conclusion
Polyvagal theory has achieved something valuable: it has given many people a language for states they previously had no words for. As a neurophysiological model, however, it stands on very shaky ground after the 2026 evaluation. The sensible thing is to keep the two apart: keep the practice – slow breathing, relaxation methods, mindfulness, bodily self-awareness. Let go of the story about the two vagal branches. Your ability to calm yourself does not depend on the theory being correct.
Would you like to know what actually works for you?
In coaching we test rather than believe: we look at which methods genuinely change something in your everyday life – and which you can safely leave out.
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