Your body reacts before your mind understands what's happening. Your heart races, your hands sweat, your stomach tightens. Or the opposite: you disconnect, everything becomes distant, you feel you're not quite here. That's not weakness or exaggeration: it's your nervous system doing its job.
Understanding how that internal machinery works is the first step towards no longer feeling at its mercy.
The autonomic nervous system: autopilot
The autonomic nervous system (ANS) regulates functions you don't consciously control: heart rate, breathing, digestion, the response to danger. It divides into two main branches that work like an accelerator and a brake.
The sympathetic system: the accelerator
The sympathetic nervous system activates when your body perceives a threat (real or perceived). It's the fight-or-flight response: it releases adrenaline and cortisol, speeds up the heart, tenses the muscles, diverts blood from digestion to the limbs. It prepares you to act.
In situations of real danger, it's a vital response. The problem appears when this activation becomes chronic — when you live with the accelerator floored without any real danger, because your nervous system stayed calibrated for survival.
The parasympathetic system: the brake
The parasympathetic nervous system does the opposite: it decelerates, restores, allows digestion, rest and recovery. It's the "rest and digest" state — the opposite of fight or flight.
But the parasympathetic has two modes. Stephen Porges, in his polyvagal theory, describes the vagus nerve (the main parasympathetic pathway) as divided into two branches: the ventral vagus, associated with calm, social connection and safety; and the dorsal vagus, associated with disconnection, collapse and dissociation when the system feels completely overwhelmed.
What happens when the system dysregulates?
In a person with a well-regulated nervous system, there's a dynamic balance between activation (sympathetic) and calm (parasympathetic). You can activate for a challenge and then return to calm. The problem arises when that balance breaks:
- Chronic sympathetic hyperactivation: constant anxiety, hypervigilance, difficulty resting, insomnia, irritability, permanent muscle tension.
- Chronic dorsal hypoactivation: disconnection, unexplained fatigue, apathy, feeling "switched off", difficulty feeling emotions.
- Oscillation between both: alternating between states of intense anxiety and emotional "blackout" without being able to stay in a middle ground.
Your nervous system isn't broken — it's doing exactly what it learned to do to protect you. But what protected you then may be limiting you now.
Why does understanding this matter?
Because many of the things that happen to you — anxiety, reactivity, disconnection, difficulty being present — aren't abstract psychological problems. They're expressions of a nervous system that needs to learn to regulate differently.
Work with nervous activation is central to somatic accompaniment and to the treatment of trauma, especially complex trauma. Cognitively understanding what's happening isn't enough — your body needs to learn a new way of being in the world.
The first step
Before trying to regulate your activation, the first step is recognising it. Start noticing what state your nervous system is in throughout the day: Am I revved up? Am I switched off? Am I somewhere in between, where I feel present and connected?
That awareness, by itself, is already the beginning of change.