The Autonomic Balance — Why Calm Isn’t Always the Answer

I want to start with a correction to a framing that has become so prevalent in the wellness space that it has begun to distort clinical thinking.

The sympathetic nervous system is not the villain. Fight-or-flight is not a malfunction. Cortisol is not a toxin. Being driven, alert, activated, productive, and highly engaged with your work is not, in itself, a clinical problem.

The problem — the genuine, measurable, physiologically costly problem — is when the system never comes down. When the switch between activation and recovery stops working. When the body is running a sympathetic programme in situations that don’t require it, and cannot access the parasympathetic programme even when conditions for recovery are present.

That is a flexibility problem. And flexibility, it turns out, is the thing we should be measuring, not the absolute level of activation or calm.

What the autonomic nervous system actually does

The autonomic nervous system runs everything you don’t consciously control: heart rate, blood pressure, digestion, immune activation, respiratory rate, pupil dilation, sexual function, sweating, the rate at which your gut moves food through, the degree to which your immune system is primed for response. It operates through two primary branches that are broadly antagonistic — each suppresses the other when it is dominant.

In a healthy, flexible system, these two branches respond appropriately to context. A threat appears — the sympathetic branch activates. The threat resolves — the parasympathetic branch restores. The transition between the two is relatively smooth, relatively fast, and driven by the situation rather than by a chronic background state.

This is what heart rate variability (HRV) measures — not whether your heart beats slowly, but how flexibly it responds to changing demands. High HRV means the autonomic system is responsive and well-regulated. Low HRV means it is rigid — either chronically activated or chronically suppressed — and rigid systems are fragile systems.

The three states, not two

Stephen Porges’ Polyvagal Theory, which has generated significant research interest and some healthy debate since its introduction in the 1990s, makes a distinction that I find clinically very useful: there are not two autonomic states but three.

The familiar two are sympathetic activation (fight-or-flight) and ventral vagal parasympathetic (rest-and-digest, social engagement, safety). But Porges identifies a third state — dorsal vagal shutdown — which is the oldest evolutionary response and activates under conditions of inescapable threat or overwhelm.

Dorsal vagal shutdown looks, superficially, like parasympathetic calm. Heart rate slows. The person becomes quiet, withdrawn, perhaps difficult to reach. But it is not calm — it is collapse. The dissociation, the emotional numbing, the profound fatigue that doesn’t respond to rest, the inability to feel pleasure or connection — these are dorsal vagal, not parasympathetic. And treating them with more rest, more relaxation, more parasympathetic-targeted interventions misses the point entirely.

What chronic sympathetic dominance actually looks like

The presentations of chronic sympathetic dominance are well documented and probably familiar to anyone who has worked in functional medicine or read seriously in this area. But it is worth listing them clearly, because they are frequently attributed to other causes and treated symptomatically rather than systemically.

• Difficulty falling asleep despite physical tiredness — the mind remains alert after the body has given up
• Waking between 2am and 4am, unable to return to sleep — often a cortisol spike driven by blood sugar instability or HPA activation
• Jaw clenching, teeth grinding, neck and shoulder tension — sympathetic tone held in the musculature
• Digestive dysfunction — IBS, bloating, incomplete digestion, constipation — driven by suppressed parasympathetic gut function
• Elevated resting heart rate, reduced HRV
• Difficulty feeling genuinely hungry or genuinely full — appetite regulation disrupted by chronic stress hormones
• Reduced libido — reproductive function is suppressed under sustained sympathetic load
• Recurrent infections — the immune system under chronic cortisol exposure becomes dysregulated, not simply suppressed
• The inability to genuinely rest even when the opportunity is present

The problem nobody talks about: parasympathetic lock-in

This is the part of the autonomic conversation that the wellness industry consistently misses, and that I want to spend some time on because it has real clinical consequences.

Not everyone who comes to see me is running too hot. Some are running too cold.

The person with severely blunted cortisol — flat curve from morning to night, no reactivity, profound fatigue, inability to respond to demands, emotional flatness, social withdrawal — is not well-rested. They are depleted. The HPA axis has adapted downward after years of chronic demand, and what looks like calm is actually exhaustion wearing calm’s clothes.

Pushing more parasympathetic activity at this person — more meditation, more yin yoga, more slow breathing — is the wrong intervention. It may feel comfortable because it doesn’t require the activation they can’t generate. But it will not rebuild the cortisol response they need to function. What they actually require is graduated activation — carefully applied sympathetic stimulation, through cold exposure, resistance training, novel challenge, social engagement — to begin rebuilding the capacity to respond.

Similarly, the person in dorsal vagal shutdown — dissociated, numb, withdrawn, unable to feel pleasure or safety — does not need more rest. They need titrated activation that moves them through the sympathetic window and into ventral vagal safety, not directly into more shutdown. This is delicate work and usually requires skilled therapeutic support rather than a self-help protocol.

Building autonomic flexibility

The goal, stated clearly: a nervous system that can activate fully when the situation requires it, recover efficiently when the demand passes, and access genuine safety and connection in appropriate contexts. Not a system that is always calm. A system that can move.

The interventions that build this flexibility are reasonably well established, though individual responses vary and sequencing matters:

Breath work with both directions. Slow, extended exhalation activates the parasympathetic branch via the vagus nerve — this is well documented and useful for recovery. But breath holds, brief hyperventilation, and high-intensity breathing patterns also have a role for people who need to rebuild activation capacity. The intervention should match the direction of the deficit.

Cold exposure, graduated. Cold water immersion and cold showers produce a predictable sympathetic activation followed by a parasympathetic rebound. For people with depleted HPA function, this graduated activation-recovery cycle can help rebuild the cortisol response. For people already chronically activated, the post-exposure parasympathetic rebound is the useful part.

Resistance training. The hormetic stress of resistance exercise — a controlled, time-limited sympathetic activation followed by recovery — is one of the most reliable builders of autonomic flexibility in the literature. The key is the recovery phase: if training is stacked without adequate recovery, it compounds the chronic activation load rather than building flexibility.

Social connection. Porges’ ventral vagal system — the one associated with safety, social engagement, and genuine recovery — is activated specifically by face-to-face social interaction, prosodic speech, eye contact, and co-regulation with another nervous system. Screen-based interaction does not fully replicate this. The evidence for social connection as a direct autonomic intervention is increasingly robust.

Nature exposure. As noted in the present moment post, time in natural environments produces measurable reductions in sympathetic tone and improvements in HRV that indoor environments do not replicate. The mechanism is not fully established but the finding is consistent enough to be clinically relevant.

The Inner Architecture and the autonomic system

This series has covered beliefs, forgiveness, purpose, present-moment awareness, and now the autonomic system. The thread connecting all of them is the same: the psychological and existential dimensions of a person’s life are not separate from their physiology. They are expressed through it.

A person who holds a belief that their body is broken runs a different autonomic pattern than one who believes recovery is possible. A person carrying a long-held grievance activates their HPA axis on a regular loop. A person without a sense of purpose shows a measurably different cortisol curve from one with clear direction. A person who cannot access the present moment is running default mode network activity that keeps the sympathetic system primed.

And underlying all of it, regulating the body’s response to all of these inputs, is the autonomic nervous system — not as a passive responder to circumstances but as an active interpreter of what those circumstances mean. A nervous system that has learned, through experience, that the world is safe will read ambiguous situations differently from one that has learned the opposite. The interpretation shapes the response. The response shapes the biology.

This is the terrain. Not just the gut microbiome, not just the hormone panel, not just the inflammatory markers — though all of those matter and all of them respond to the autonomic state. The terrain includes the inner architecture that the autonomic system is running on.

Test, don’t guess. And then ask the harder questions.

The complete Inner Architecture series

• Part One: What You Believe About Yourself Is a Clinical Variable
• Part Two: Forgiveness But Don’t Forget
• Part Three: What Are You For? Life Purpose & Existential Angst
• The Present Moment: This Moment Is the Only One That’s Actually Happening
• Deep Dive: The HPA Axis — How the Stress Response Actually Works