What Causes Trauma? The Events and Conditions That Overwhelm the Nervous System

Written by Roland Bal

There are many factors that can contribute to developing trauma — too many to list exhaustively. What follows is a condensed overview meant to provide you with some guidelines. But before the list, something needs to be said about what actually makes an experience traumatic, because the answer is not as straightforward as it seems.

What Makes an Experience Traumatic

Not every difficult experience becomes a trauma. And not every experience that looks mild from the outside is free of lasting impact. What determines whether something becomes traumatic is not the event itself — it is whether the nervous system was overwhelmed beyond its capacity to cope, and whether that overwhelm was ever resolved.

A child who falls off a bicycle and is immediately held by a calm parent will likely process the shock and move on. A child who falls and is screamed at, or ignored, or told to stop crying, may carry that moment in their body for decades. The event is the same. The nervous system response — and what happened afterward — is what makes the difference.

This is why trauma is so much broader than most people realise. It is not limited to war, assault, or catastrophe. It includes anything that left an emotional residue in the system that was never fully processed — and that residue continues to interfere with normal daily functioning.

The Range of Causes

The causes of trauma fall broadly into two categories: shock trauma (single overwhelming events) and developmental trauma (chronic conditions, usually in childhood). Many people carry both.

Compromised attachment bonds and child abuse — including neglect, abandonment, misattunement, being unwanted, family secrets, debt, divorce, depressed or addicted parents, ongoing verbal and physical abuse — are among the most common and least recognised causes. Sexual abuse, ritual abuse, and rape. Loss of a loved one, particularly in childhood. Bullying. Medical causes such as hospitalisations, surgeries, chronic illness, invasive medical procedures, anaesthesia, burns, and poisoning. Fetal distress and traumatic birth. Accidents including falls, high-impact collisions, head injury, and electrocution. Suffocation, drowning, and strangulation. Attack — including rape, war, bombings, physical abuse, mugging, molestation, stabbing, gunshot wounds, and animal attacks. Natural and man-made disasters such as earthquakes, fires, tornadoes, floods, terrorism, and dislocation from community. Horror — seeing an accident, watching someone else being abused or killed, being responsible for hurting someone. Torture and systematic abuse. Prolonged periods of stress. And narcissistic abuse — which includes ongoing emotional, psychological, and verbal abuse, gaslighting, coercion, and manipulation.

This list is not exhaustive. Stalking, kidnapping, being held captive, moral injury, homelessness, and secondary exposure — the kind that affects first responders, healthcare workers, and those living with someone who is traumatised — can all produce the same nervous system overwhelm.

Why the "Small" Causes Matter Most

The causes that are easiest to miss are often the ones that do the most lasting damage. A single car accident is visible, concrete, time-stamped. Childhood neglect is none of those things. It is the absence of something — safety, attunement, emotional presence — spread across years. There is no single moment to point to. There is only the accumulation of what was missing.

This is why so many people who carry deep trauma do not believe they have it. Their experience does not match the cultural image of trauma as a dramatic event. They think "nothing happened to me" — when in fact what happened was that nothing happened when something should have. No one came. No one noticed. No one made it safe. And the nervous system adapted to that absence in ways that are still running decades later.

It Is Not the Event — It Is What Was Left Unresolved

Two people can go through the same event and come out differently. One shakes it off. The other carries it for life. The difference is not toughness or weakness. It is the state of the nervous system at the time of the event, the support that was available afterward, and whether the survival energy that was mobilised was ever discharged.

When the nervous system mounts a fight-or-flight response and that response is completed — through movement, through shaking, through being held — the energy dissipates and the system returns to baseline. When that response is interrupted or suppressed — because you were too young, too alone, too ashamed, or the threat was ongoing — the energy stays locked in the body. That is what trauma is. Not the event. The unfinished business of the nervous system.

Understanding this changes everything about how we approach recovery. You do not need to relive the event. You need to help the nervous system complete what it started. That is what somatic work makes possible — meeting the body where the residue lives, and giving it the conditions to finally let go.