When Triggers Take Over: How Unprocessed Trauma Hijacks the Nervous System

We often hear that “the body knows” or that our nervous system never lies. That’s only half the truth. The nervous system is an extraordinary guide but only when our traumatic imprints have been processed enough so the body can tell the difference between “then” and “now.” When trauma remains unhealed, the nervous system becomes confused. It detects threat where there is none, amplifies minor signals, and treats everyday conflict or stress as if survival is at stake.

This is not intuition.

This is dysregulation.

And it explains why triggers can feel so overwhelming, so fast, and so irrational even to the person experiencing them.

What a Trigger Really Is - Beyond the Buzzword

A trigger is not a “bad mood”, not sensitivity, not weakness, and not overreacting.

A trigger is a neurobiological replay. It happens when current sensory information (a tone of voice, a movement, a look, a silence, a smell, a phrase) activates neural networks formed during earlier overwhelming experiences. This activation usually occurs in under 1/10 of a second before conscious awareness or reasoning comes online. The brain is not deciding; it is remembering through the body. Research on implicit memory (Brewin, van der Kolk, Siegel) shows that trauma stores itself not only as narrative memory but as:

• sensations,

• emotions,

• tension patterns,

• autonomic responses,

• and threat perceptions.

So when a trigger appears, the body reacts as though the original event is happening again. This is why nothing about the reaction feels “in the present.”

The Neurobiology of a Triggered State

When trauma is unresolved, the nervous system leans toward two chronic modes:

• hyperarousal (fight/flight),

• hypoarousal (freeze/shut down).

Below is what happens inside the brain and body.

1. The Amygdala Becomes Overactive

Research demonstrates that trauma produces lasting changes in the amygdala the brain’s alarm system. It fires too quickly and too intensely.

This leads to:

• misinterpreting neutral signals as dangerous,

• heightened emotional responses,

• difficulty calming down,

• sensitivity to tone, posture, or conflict.

The amygdala’s job is to protect; unhealed trauma makes it overprotective.

2. The Prefrontal Cortex Temporarily Shuts Down

The prefrontal cortex (PFC) is responsible for:

• emotional regulation,

• impulse control,

• reasoning,

• perspective-taking,

• choosing behaviours aligned with values.

During triggers, the PFC goes “offline. ”Functional MRI studies show dramatic decreases in PFC activity during trauma reminders.

This is why a triggered person:

• “can’t think,”

• becomes irrational,

• can’t explain their feelings,

• acts impulsively,

• or loses access to long-term perspective.

They are not choosing; their brain is choosing for them.

3. The Hippocampus Struggles With Time Perception

Trauma impacts the hippocampus the structure that organizes memory in time and space.

When it becomes dysregulated:

• the past feels present,

• memory fragments intrude into current experience,

• context becomes distorted,

• emotions lose proportion.

People say things like:

• “I know it’s not the same, but it feels the same.”

• “My body reacts before I even understand why.”

• “This came out of nowhere.”

This is neurobiology, not drama.

4. The Autonomic Nervous System Goes Into Survival Mode

The Polyvagal Theory explains how trauma reshapes the autonomic nervous system (ANS).Unhealed trauma leads to false alarms the body reacts as if danger is real even when the environment is safe.

Common physiological responses:

Hyperarousal (fight/flight):

• fast heart rate

• shallow breathing

• tension in chest or stomach

• anger, panic, agitation

• urge to escape or explain

• overthinking

• emotional intensity

Hypoarousal (freeze/shutdown):

• emotional numbing

• dissociation

• exhaustion

• disconnection

• collapsing inward

• feeling “not here”

• lack of words

Both are evolutionary survival states, not conscious decisions.

Why Trauma Leads to “Inadequate” Reactions

If trauma is unprocessed, the body cannot distinguish:

• discomfort from danger,

• disagreement from threat,

• boundaries from rejection,

• conflict from violence,

• emotional intimacy from losing control.

So the reaction becomes bigger than the situation. This is not immaturity. It is a nervous system reacting to old pain with old strategies in new contexts.

The Cost of Unprocessed Triggers

Unhealed trauma can quietly shape:

Relationships

Partners walk on eggshells. Arguments escalate quickly. Emotional closeness becomes unsafe.

Self-worth

You may interpret neutral behaviour as criticism or abandonment.

Decision-making

Triggers lead to impulsive choices or avoidance.

Identity

You may believe you are “too much,” “too sensitive,” or “broken.”

Daily functioning

Chronic hypervigilance drains cognitive and emotional energy.

Triggers are not the problem. The unresolved trauma behind them is.

What Healing Actually Changes

Healing doesn’t mean eliminating all triggers that’s not realistic. It means building differentiation between the past and the present. Through therapies like EMDR, somatic approaches, internal family systems, and memory reconsolidation techniques, healing allows:

• trauma memory to integrate,

• the amygdala to calm,

• the prefrontal cortex to stay online longer,

• the hippocampus to organize memory correctly,

• the autonomic nervous system to return to safety faster.

The trigger becomes:

“Something inside me is activated… but I am here, and I am safe.”

This is the beginning of nervous system accuracy and the return of emotional freedom.

Final Thought

Your nervous system is not your enemy. It's doing exactly what it learned long ago. But it doesn’t have to stay stuck in the past. When trauma is healed, the body stops repeating old stories and starts responding to the life that is actually happening.

Sources (Research-Based)

• van der Kolk, B. A. (2014). The Body Keeps the Score.

• LeDoux, J. (2000). “Emotion circuits in the brain.” Annual Review of Neuroscience.

• Lanius, R., Bluhm, R., & Frewen, P. (2010). “The neurobiology of PTSD.” Brain Research.

• Porges, S. W. (2011). The Polyvagal Theory.

• Siegel, D. J. (2012). The Developing Mind.

• Brewin, C. R. (2014). “Memory reconsolidation and intrusive memories.” Psychological Bulletin.

• Thayer, J., & Lane, R. (2000). “A model of neurovisceral integration.” Biological Psychology.

• Shvil, E. et al. (2014). “PTSD and amygdala hyperactivity.” Biological Psychiatry.

• Hayes, J. P. et al. (2012). “Hippocampal dysfunction in trauma.” Neuroscience & Biobehavioral Reviews.

• Maren, S. (2001). “Neurobiology of fear conditioning.” Annual Review of Neuroscience.