A nervous system is not a horoscope

The body's new astrology

Scroll through your timeline for an evening and your nervous system will come past on its own. It is "dysregulated", your vagus needs a "reset", you are "stuck in dorsal" and a thirty-second breathing exercise brings you "back to ventral". It sounds like biology and feels like self-care. It also has something of a horoscope about it: vague enough to always fit, precise enough to sound scientific.

That is a pity, because underneath the noise lies real and usable physiology. It pays to separate what stands from what wobbles.

What stands firm

Your autonomic nervous system works largely outside your conscious control. The sympathetic part readies your body for action: heart rate up, muscles tense. The parasympathetic part, with the vagus nerve as an important connection, brakes and restores. This is textbook material, ever since Walter Cannon described in 1915 how fear and anger mobilise the body.

Also well established: breathing out slowly affects your heart rhythm. On the in-breath your heart speeds up slightly, on the out-breath it slows. That fluctuation is called respiratory sinus arrhythmia, and you can influence it with your breathing. Sleep, movement and time with people you trust have a measurable effect on your stress physiology. No fashionable term is needed for that.

What wobbles

Much of the popular vocabulary comes from Stephen Porges's polyvagal theory, which he introduced in the mid-nineties. The theory describes an evolutionary ladder of three states: social safety, mobilisation and freezing, each tied to a specific part of the nervous system. It is an elegant story, and in therapy rooms it has become a favourite tool.

The scientific criticism, however, is not gentle. In 2023 the psychophysiologist Paul Grossman published an analysis in Biological Psychology dismantling the theory's five basic premises one by one. Among other things he contests the evolutionary claims and the role assigned to particular vagal nuclei. In 2026 an international expert evaluation followed, with Grossman as first author, concluding that the theory as a whole is untenable. Porges responded with a rebuttal arguing that his critics are fighting a caricature.

This is interpretation, not fact: that you as a layperson cannot settle this anatomical dispute is not a weakness but realism. What you can see is that a theory fundamentally contested by leading physiologists is no basis for confident promises in an advertisement.

Something to take with you: when someone sells you something using "your nervous system", ask which part of the claim is measurable and which part is an image. Images are allowed, as long as they do not play the part of evidence.

The strongest counterpoint

There is an honest argument for the polyvagal language, and it deserves room. Many therapists say the model helps their clients understand bodily reactions without shame. Someone who freezes in a confrontation and felt weak for years suddenly hears that their body was trying to protect them. That can be liberating, regardless of whether the anatomy is exactly right.

That is not an unimportant point. Many useful metaphors are anatomically wrong. The danger only arises when the metaphor starts to rule: when protocols, training courses and products are sold with the suggestion that they rest on settled neurobiology.

What a builder can do with it

For anyone running a company, the practical lesson is sober. You do not have to climb a ladder. You only have to let your stress system genuinely switch off now and then. That asks for no app and no certificate, but for a few dull and proven things: enough sleep, daily movement, deliberately slow out-breaths when tension rises, and time with people around whom you do not have to perform.

It sounds less exciting than a "vagus reset". It does work. And it has one great advantage over any hype: it stays true even when the next theory falls.