Under Pressure: The Physiology of High-Stress Trades

High-stress trades such as firefighting, policing, paramedicine, bomb disposal and emergency response share a single purpose: to protect life.

They are humanitarian by nature, roles built on calm under pressure, centred in chaos, and a willingness to walk toward danger for the sake of others.

The biology of readiness

In high-stress environments, the brain’s alarm system mainly the amygdala and brainstem signals potential danger. The autonomic nervous system then shifts instantly into a state of mobilisation: adrenaline and cortisol rise, heart rate and blood pressure increase, vision sharpens, digestion pauses.

This is the body’s ancient survival code: mobilise to protect.

Through training and repetition, these systems become highly efficient. Neural pathways strengthen between the brain’s threat circuits and the body’s physiological responses. The vagus nerve which helps calm the body after danger can become less responsive over time. For some people in high-mobilisation roles, repeated high-stress exposures may contribute to difficulty shifting out of mobilisation mode and into rest/recovery.

In short, the body learns, through training and experience, readiness as a baseline. But it’s rarely trained to return to calm what’s called the parasympathetic state within the nervous system.

That conditioning is vital in the field, but once the environment changes, it can be difficult to stand down. The nervous system stays slightly charged scanning, anticipating, preparing for the next shout.

How it can show up at home

When a system remains in this state of hyper-readiness, everyday life can feel unpredictable.

Loud noises, conflict, emotional intensity, or even relaxation can trigger the same neural patterns that once signalled threat.

This can look like:

• Irritability or emotional shutdown after small stresses

• Restlessness, difficulty sitting still, or sleeping deeply

• Avoidance of intimacy or vulnerability

• Over-control, needing order or quiet to feel safe

• Difficulty reading others’ emotional cues

From the outside, it might seem like distance, irritation, or indifference.

Physiologically, it’s the body protecting itself a survival system doing its best to stay in control.

The relational field

Families often learn to regulate around this state. Partners and children tune into cues softening voices, avoiding triggers, anticipating moods. Over time, they can internalise the same vigilance, living in synchrony with a loved one’s activated system.

This isn’t failure; it’s co-regulation.

But without understanding, both sides can misread the signals. The operator feels misunderstood; the family feels rejected. In truth, both are responding to the same physiology one that has never been shown how to switch off safely.

It’s important to remember this isn’t just a mind thing; it’s a body thing and it’s far more common than people realise. Many think it’s “just them,” and it isn’t.

In high-stress vocations, many are now seeing the benefits of finding ways to train the body back into a state of rest through practices such as cold-water immersion, meditation, breathwork, or exercise. (My husband a firefighter, finds his wellness in movement; I prefer cold water and meditation.) There’s no one-size-fits-all approach, but learning to shift out of hyperarousal can be a game changer.

The way forward

Because these patterns are learned, they can also be unlearned.

Neuroplasticity the brain’s ability to rewire itself allows the nervous system to gradually recalibrate through safety, connection, and regulation practices such as:

• Slow breathing or grounding to stimulate the vagus nerve

• Gentle cold-water immersion to retrain stress tolerance

• Mindful movement, yoga and time in nature

• Honest, compassionate communication within trusted others

Along with many other practises……

These aren’t wellness trends. They’re physiological retraining, reminders that a body in a state of calm is actually safe, something many in high-stress trades rarely get to practise. While everyone’s nervous system responds differently, recovery and regulation practices are essential in helping the body stand down after being on high alert. There’s no magic bullet, but making space for recovery matters.

Why this matters

Understanding the science behind high-stress trades removes shame and blame from the story.

It shows that what we call “emotional distance” or “irritation” is often just the echo of long-term mobilisation.

And once we see it that way, we can replace judgement with compassion for those who serve and for those who love them.

That’s what The Aftershock Project stands for: bringing together physiological understanding, relational care, and practical tools for those whose bodies learned to protect others and who are now learning to tell their minds, hearts and bodies it’s safe to stand down.

Resources for Training Your Nervous System

If you’d like to explore this more, here are a few accessible resources:

• 📖 The Body Keeps the Score by Bessel van der Kolk – A brilliant and very readable book on how stress shapes the body and mind, and how practices like mindfulness, yoga, and breathwork can help us come back into balance.

• 📚 Waking the Tiger by Peter Levine – A practical guide to noticing and releasing stored tension through body awareness.

• 🎧 HeadFIT for Life – A free MoD-backed resource with quick breathing, posture, and focus tools designed for the forces community (but useful for anyone).

• 🎙️ Combat Stress Podcast – UK veterans and clinicians sharing honest stories and tips on managing stress and hyper-vigilance.

• 🎧 Therapy in a Nutshell (podcast/YouTube) – Clear, short explanations of the stress cycle and simple tools to reset the nervous system.

• 🔬 Dharma Lab – An accessible project exploring the science of meditation, offering talks and resources on how contemplative practices reshape the brain and body.