Trauma and the Nervous System: Why the Body Remembers

By Ann Sullivan, RTC, SEP, ASAT Registered Therapeutic Counsellor | Somatic Experiencing Practitioner | Vancouver Island, BC

There is a moment I have witnessed many times in my office. Someone is telling me about something that happened years ago, sometimes decades ago. They are using calm language. They are being articulate and thoughtful. And then something shifts. Their breath changes. Their eyes go somewhere else. Their hands grip the arm of the chair without them noticing. The story they are telling with their words and the story their body is telling are two completely different things.

This is trauma. Not the event itself, but what the nervous system did with it. And what the nervous system did with it is still happening, right now, in the room, in the body of the person sitting across from me.

Understanding why this happens is not just academically interesting. It is the beginning of compassion. For yourself, and for the parts of you that have been trying, in the only ways they knew how, to keep you safe.

What Trauma Actually Is

Trauma is not what happened to you. Trauma is what happened inside you as a result of what happened to you.

This distinction matters enormously. Two people can experience the same event and be affected very differently. One walks away shaken but intact. The other carries it in their body for years. This is not about strength or weakness. It is about the state of the nervous system at the moment of the experience, the resources available, the relationships that were or were not present afterward, and the history the nervous system brought into that moment.

Your autonomic nervous system is constantly assessing the environment for safety, danger, and life threat through a process called neuroception. I wrote about this in detail in Your Body Is Not Broken, and it is worth returning to here, because it is the foundation for understanding what trauma does to the system.

When neuroception detects something overwhelming, something the system does not have the resources to meet, it responds. The sympathetic system mobilises for fight or flight. If that is not possible or not enough, the dorsal vagal system pulls the brakes. Shutdown. Freeze. Collapse.

Trauma occurs when the nervous system activates a survival response and then cannot complete it. The energy that was mobilised for fight or flight has nowhere to go. The freeze that protected you in an impossible moment does not fully release when the moment passes. The system gets stuck somewhere on the spectrum, and it stays there, sometimes for years, sometimes for a lifetime, unless something intervenes.

That something is what we do in therapy.

Why Trauma Lives in the Body

The phrase "the body keeps the score" has entered the cultural conversation in recent years, and for good reason. It describes something I see every day in my practice. Trauma is not stored in the thinking mind. It is stored in the nervous system, in the muscles, in the breath, in the posture, in the patterns of activation and shutdown that become the baseline of a person's daily experience.

This is why people can talk about traumatic experiences for years without those experiences losing their charge. Talking about something engages the prefrontal cortex, the thinking brain. But trauma lives deeper than that. It lives in the parts of the brain and body that predate language, that operate below conscious thought, that are still running the survival calculations of a moment that is long past.

I have worked with people who intellectually know that they are safe. They can tell me this clearly and believe it completely. And yet their nervous system is living as though the threat is still present. The hypervigilance. The startle response. The inability to rest. The relationships that never quite feel secure enough. The body that will not let down its guard.

This is not irrationality. This is a nervous system doing its job, based on the information it has. It learned, at some point, that the world was not safe. And until it has new experiences that teach it otherwise, it will keep operating from that learning.

What Trauma Looks Like in Daily Life

Trauma does not always announce itself. It does not always come with a clear memory attached. Many of the people I work with do not think of themselves as traumatised. They think of themselves as anxious, or difficult, or broken, or stuck.

They describe not being able to sleep even when they are exhausted. Being easily overwhelmed by things that seem manageable to others. Feeling disconnected from their own emotions, or flooded by them without warning. Struggling to stay present in relationships even with people they love. A persistent low-level sense that something bad is about to happen, even when everything looks fine.

They describe shutting down in moments when they most want to be open. Saying yes when they mean no, because the alternative feels dangerous even when it is not. Reaching for things that numb, food, alcohol, screens, busyness, because the internal noise is too loud to sit with.

None of this is a character flaw. All of it makes sense when you understand what the nervous system has been through, and what it has been trying to do.

Trauma and Relationship

Of all the contexts in which trauma expresses itself, relationship is perhaps the most common and the most painful. This is not a coincidence. Most trauma, even trauma that looks situational, has a relational dimension. It happened in the presence of another person, or in the absence of one. It involved a rupture in safety that was also a rupture in connection.

The nervous system learns about safety primarily through relationship. From the very beginning of life, the co-regulation of another person, the soothing presence of someone who is calm and attuned, is what teaches the developing nervous system that it is safe to settle. When that co-regulation is absent, or inconsistent, or actively harmful, the system learns something different. It learns that connection is dangerous. Or that it must be earned. Or that it will always eventually disappear.

This early learning does not stay in childhood. It travels forward. It shapes the nervous system's response to every relationship that follows. The person who shuts down when a partner raises their voice. The person who cannot tolerate silence in a relationship because silence was never safe. The person who keeps choosing partners who recreate a familiar kind of pain, not because they want to suffer, but because the nervous system is drawn toward what it knows.

I see this pattern constantly. And what I want people to understand is that this is not fate. The nervous system learned these patterns. It can learn new ones. But that learning requires more than insight. It requires experience. Repeated, safe, relational experience that teaches the system something different.

What Healing Actually Requires

There is a reason that simply understanding your trauma is not enough to heal it. Knowledge is valuable. It is often the beginning of compassion. But the nervous system was not shaped by ideas. It was shaped by experience. And it must be reshaped by experience.

This is what therapy offers, at its best. Not just a place to tell your story, though that matters enormously. Not just a place to gain insight, though that matters too. But a relational experience that is different. An experience of being heard without judgment. Of having your responses understood rather than pathologised. Of finding that it is safe to feel, and safe to say what is true, and safe to not know.

In my practice, this happens primarily through conversation. The relationship we build in the room is not incidental to the work. It is the work. The nervous system of the person across from me is in relationship with mine, constantly, reading for safety or threat, deciding how much it is willing to let down its guard. When that relationship feels safe enough, things begin to move that have been stuck for a very long time.

Sometimes what is held in the body needs something more than words to reach it. When that is true, we work more directly with breath, with sensation, with what the body is doing in the moment. But this is always in service of the conversation, always at the pace the person can tolerate, always with the understanding that slow is fast. The nervous system cannot be pushed. It can only be invited.

A Note on Time

Healing from trauma is not linear. It does not follow a schedule. There are sessions that feel like breakthroughs and weeks that feel like nothing has changed. There are moments of genuine settledness and moments when the old activation comes roaring back as though nothing has shifted at all.

This is normal. It is part of the process. The nervous system does not reorganise itself all at once. It does so gradually, in small increments, building new pathways alongside the old ones until the new ones become more available, more familiar, more like home.

I tell my clients that healing is not the absence of the old responses. It is having more choice about them. More space between the trigger and the reaction. More capacity to notice what is happening and to meet it with something other than the survival response that has always been the only available option.

That space is everything.

If you recognise yourself in any of this, if the hypervigilance or the shutdown or the relational patterns feel familiar, you do not have to keep carrying this alone. What happened to you made sense. What your nervous system did with it made sense. And the fact that it is still happening, still shaping your days and your relationships and your sense of yourself, also makes sense.

You are not broken. You are a nervous system that learned to survive something. And survival, as I wrote in Your Body Is Not Broken, is something to be honoured.

Even as we make room for something more.

This is where the work begins.