WHAT IS TRAUMA?

Understanding Your Nervous System, PTSD, and Why Your Reactions Make Complete Sense

Part One of a Two-Part Series on Trauma & Complex PTSD|Nadia Samuelsson, Trauma-Specialised Psychologist

"I keep waiting for something bad to happen. Even when life is fine, I can't relax. I've always been like this — I just thought it was my personality."

If this feels familiar, keep reading. What you’re describing isn’t your personality. It’s not just a trait or being dramatic, and it’s not something you can simply change by thinking differently.

Your nervous system is doing exactly what it learned to do from experience, not by choice.

The word trauma is used a lot these days, but it’s still often misunderstood. Many people think of trauma as something dramatic and obvious, like war, disaster, or violent assault. But this view leaves out many people who live with the lasting effects of experiences they were never allowed to call trauma. This article is for them—and maybe for you too.

By the end of this article, you’ll know what trauma really is—biologically, psychologically, and physically. You’ll see what PTSD looks like in daily life and in the nervous system, why your reactions aren’t signs of weakness, and what can help your nervous system truly heal. Part Two will look at Complex PTSD, which develops over years in unsafe relationships. For now, let’s start with the basics.

What Trauma Actually Is

It Is Not the Event — It Is What the Event Did to Your Nervous

System

Here is the definition that changed trauma treatment for an entire generation of clinicians. It comes from Peter Levine, the founder of Somatic Experiencing:

"Trauma originates as a response in the nervous system, and does not originate in an event. Trauma is in the nervous system, not in the event." — Peter Levine.

Trauma isn’t about the event itself. It’s about how your body and mind responded to it. Two people can go through the same experience, but one might recover while the other has lasting symptoms. The diff erence isn’t about strength or character, or even the event itself. It’s about what the nervous system could handle at the time, based on its history, resources, and support.

Judith Herman, the psychiatrist who fi rst described Complex PTSD, explains that all traumatic experiences share a sense of intense fear, helplessness, loss of control, and feeling threatened. It might not look dramatic from the outside, but it feels crushing on the inside.

There’s evidence that biology, not just the event, shapes the impact. In 1946, David Levy’s research at New York Hospital showed that children’s reactions to routine hospital stays were as severe as the symptoms seen in combat veterans. Similar nervous systems and survival biology, but very diff erent triggers.

Trauma isn’t only about the worst-case scenarios. It’s any experience that overwhelms your nervous system’s ability to cope and recover. It’s also much more common than most people think.

Your Nervous System: The Architecture of Survival

The Two Branches and How They Work

Your Autonomic Nervous System (ANS) controls your survival responses and operates mostly unconsciously. You don’t choose to have a stress response. Your nervous system decides for you in a split second, using information it has gathered since before you were born.

The Sympathetic Nervous System (SNS)

is your accelerator. When it detects a threat, it mobilises the body for action: heart rate rises, breathing quickens, blood rushes to the muscles, and your digestive system goes into immediate stop. This is the fi ght-or-fl ight reaction. Its entire purpose is to get you ready to move fast.

The Parasympathetic Nervous System (PNS)

is your brake. When the threat has passed, it returns the body to equilibrium: heart rate slows, breath deepens, muscles relax, digestion resumes, and connection to others and to yourself becomes possible. This is the rest-and-digest, tend-and-befriend state.

In a healthy, well-supported nervous system, these two branches work in a natural cycle. There’s activation and recovery, stress and rest, charge and release. The system knows how to deal with challenges and return to normal. That’s what resilience really means: not avoiding stress, but being able to process it and recover.

When There Is No Way Out: The Freeze Response

When neither fi ghting nor running away can keep you safe—like when a child can’t leave a scary parent, or an adult is overpowered, or anyone is stuck in a situation where resistance isn´t possible—the nervous system uses its oldest survival strategy: freeze. This means becoming still, shutting down, or collapsing.

Freezing isn’t a failure. It’s the body’s last way to protect itself when nothing else works. This response saves energy, dulls pain, and sometimes even saves lives by making the person seem harmless or even lifeless. It’s a powerful way to survive when things feel impossible.

The challenge is what comes after. Animals in the wild discharge stored survival energy physically — they tremble, shake, run in bursts after escape. Watch a gazelle that has narrowly escaped a predator: it collapses for a moment, trembles, and then walks away. The body has completed its cycle. The survival energy is released. The gazelle does not develop PTSD.

People live in social contexts where shaking, trembling, or fi nishing a fi ght response isn’t safe, isn’t allowed, or just doesn’t happen. The survival energy that was activated stays trapped in the nervous system, cycling without release. Over time and with repeated experiences, the trapped energy becomes the root of trauma symptoms.

Trauma symptoms aren’t character fl aws or signs of weakness. They happen because a survival response was never fi nished. Your body did exactly what it was supposed to do—it just never got the message that the danger had passed.

◆CLIENT STORY — James, 29

James came to therapy because of what he called "anger issues." He went from calm to explosive in seconds, then crashed into shame and exhaustion. His partner said she had been walking on eggshells. He'd been told his whole life that he had a short fuse — that he needed to learn to control himself.

What nobody had ever named was this: James had grown up with a father who was physically unpredictable. Home had meant constant threat scanning from the time he was small. The fi ght response that was never appropriate to express as a child — because expressing it would have escalated the danger — had no outlet. Decades later, it was still fi ring. Still primed. Triggered by anything that carried even the slightest signature of the fi rst threat.

James didn’t have an anger problem. He had a nervous system that never got the chance to complete a full phase of stress and recovery. That’s what trauma is. When he started to see that—when the shame of "I just can't control myself" turned into "my body has been trying to protect me for 29 years"—something important changed in how he saw himself. That change was the real starting point for healing.

Key Takeaways — What Is Trauma?

✦Trauma is in the nervous system, not in the event — two people can experience the same thing with very diff erent outcomes.

✦Trauma is any experience that overwhelms the nervous system's capacity to process and recover.

✦The freeze response is a survival mechanism, not a sign of weakness or failure.

✦Trauma symptoms arise when survival energy gets locked in the body with nowhere to go.

✦Understanding the biology transforms shame into self-compassion — and opens the

door to healing.

PTSD — When the Nervous System Gets Stuck

What Post-Traumatic Stress Actually Looks Like

Post-Traumatic Stress Disorder (PTSD), as defi ned by the World Health Organisation (ICD-11, Code 6B40), develops after someone goes through a very threatening or terrifying event. It’s not about weakness or inability to cope. It’s about a nervous system that responded to real danger and then couldn’t turn off again.

The three core features are:

1. Re-experiencing: This means having vivid, unwanted memories, fl ashbacks, or nightmares, often with the same physical feelings as during the original event. The body can’t tell the diff erence between a memory and real danger. During a fl ashback, the nervous system reacts as if the threat is happening right now.

2. Avoidance: This is when you avoid thoughts, feelings, people, places, sounds, or situations linked to what happened—sometimes without even realising it. Avoidance can be exhausting because it works in the short term by reducing distress. But it also stops your nervous system from learning that the danger is over.

3. Persistent sense of current threat: This includes being jumpy, always on alert, having trouble sleeping, or feeling like something bad is about to happen—even when you’re actually safe. The body’s threat system stays switched on.

   
   

None of these reactions is irrational. They all come from a nervous system that learned, in context, that the world can be dangerous and that staying alert is the safest choice. The problem is, the nervous system doesn’t automatically update when the danger is gone. The old program keeps running, even though it’s no longer needed.

The Hidden Cost: Living With PTSD Day to Day

Many people with PTSD live a double life. On the outside, they seem capable and sometimes even high-achieving. On the inside, they’re exhausted, have trouble sleeping, react strongly to sudden noises, and struggle through situations that feel unsafe for reasons they can’t explain. It takes a huge amount of energy to maintain this appearance, and eventually that energy runs out.

Many people don’t seek help right after trauma, but years later, when their coping strategies stop working. Burnout sets in. The body starts to show what the mind has been holding back—chronic pain, ongoing tiredness, digestive issues, or anxiety that doesn’t seem to have a clear cause. The body always speaks up in the end.

◆CLIENT STORY — Sofi a, 34

Sofi a came to therapy for "anxiety" and persistent sleep diffi culties. In our fi rst session, she mentioned, almost in passing, that she'd been in a serious car accident three years earlier. She'd walked away physically unhurt — and she was obviously proud of that. "I dealt with it," she said. "I'm fine."

She wasn’t fi ne. Sofi a couldn’t drive on highways. She jumped at sudden sounds, such as a dropped book or a car horn, and needed time to calm down. She had stopped going to evening events because she didn’t feel safe unless she knew how to leave quickly. In restaurants, she always sat with her back to the wall, watching the door. She was exhausted and had told herself for three years that this was just who she was now.

Sofi a’s nervous system was stuck in high alert. The energy from that accident—the survival response that was never released—was still active in her body three years later. Her threat response never fi nished its cycle. This is PTSD: a trauma from one event that keeps the system locked in constant alert, always looking for danger that’s already over.

Helping Sofi a wasn’t about changing how she thought about the accident. It was about helping her nervous system learn, through physical experience, that the emergency had passed. It took time and the right approach, but it worked.

Key Takeaways — PTSD

✦PTSD develops when the nervous system cannot complete its recovery after a traumatic event.

✦The three core features — re-experiencing, avoidance, persistent threat — are survival responses, not character fl aws.

✦Living with PTSD means enormous energy spent managing the gap between appearing fi ne and feeling unsafe.

✦The body always keeps the score — physical symptoms are often trauma speaking.

✦With the right support, the nervous system can learn what the mind already knows: it is over.

Why Healing Requires More Than Talking

Where Traumatic Memory Actually Lives

Bessel van der Kolk’s important research confi rmed what trauma experts had noticed for years: traumatic memories aren’t stored like regular memories. They aren’t a clear story you can recall and look at. Instead, they’re held in the body—as sensations, posture, breathing, muscle tension, and nervous system states.

This is why you can fully understand that the accident was three years ago and that you’re safe now, but still feel your heart beating when you get near a highway. Or why you know your partner isn’t your father, but still react to a raised voice as if you’re in danger. The body’s memory doesn’t respond to logic—it responds to feeling safe. And safety has to be felt in the body, not just understood in your mind.

This is also why just understanding your trauma doesn’t always lead to change. You might learn why you react a certain way, but the reactions stay. The wound isn’t just in the story you tell—it’s in your nervous system.

Somatic Experiencing: Completing What Was Interrupted

Somatic Experiencing (SE), created by Peter Levine, helps people notice body sensations and slowly guide the body to complete survival responses that were interrupted during trauma. The goal isn’t to relive the event, but to gently release the survival energy that was never let go. This gives the nervous system the message it’s been waiting for: it’s over. You’re safe now.

This process happens in small steps, which Levine calls titration. There’s a little activation, then a return to safety, then another small step. Each cycle teaches the nervous system through experience: I can face what was overwhelming and come back. I can feel this and survive. Over time, the body’s ability to handle stress grows, hypervigilance lessens, and the body starts to trust that it can manage challenges without disaster.

Body-based trauma work often looks calm from the outside. It might mean noticing a feeling in your chest, following a small urge in your hands, or paying attention as tension turns into relaxation. But these changes happen where the wound really is—which is why this approach can create change that talking alone can’t.

The Relational Dimension: Why Safety Comes From Connection

There’s one more important part—covered more in Part Two—that belongs in any honest discussion of trauma: the nervous system doesn’t regulate itself alone. It needs relationships to help it.

From the very beginning of life, a baby’s nervous system learns to settle by connecting with a caregiver’s nervous system. Warmth, attention, and steady care help the nervous system learn how to calm down and recover from stress. But if a child grows up with caregivers who are scary, absent, or unpredictable, the nervous system learns that safety isn’t reliable, that threats can come from loved ones, and that it’s safer to stay alert than to relax with anyone.

For many people who have experienced trauma, a steady, caring, and non-judgmental relationship with a therapist is one of the fi rst times their nervous system seems truly safe. Having this experience repeatedly actually changes the nervous system—not just in theory, but in the brain itself.

You are not broken. Your nervous system learned what it needed to survive. Given the right support, those patterns can change.

Key Takeaways — Why Healing Requires the Body

✦Traumatic memory is stored in the body as sensation and nervous system state, not primarily as narrative.

✦Insight alone rarely produces lasting change — the wound must be reached where it lives.

✦Somatic Experiencing works by completing interrupted survival responses, not by re-living trauma.

✦The nervous system heals through relationship — safe connection is the mechanism, not just the context.

✦Change is possible. The body that learned to protect you can learn that it is safe to rest.

A Note Before You Go

If you’ve read this far and see yourself in James’s exhaustion, Sofi a’s constant alertness, or the idea of a nervous system that never gets to rest, I want you to know: there is nothing wrong with you. Something happened to you, and your body has been responding ever since. Those are two very diff erent things.

This is Part One of a two-part series. Part Two, "Complex PTSD: When the Wound Is the Relationship," looks at what happens when trauma isn’t just one event, but a way of living. It’s about when the danger came from inside the home, and the nervous system was formed by years of not feeling safe, not being seen, or not being allowed to have needs. If this article spoke to you, Part Two might feel even more relevant.

If any of this causes you to wonder if trauma-focused therapy could help you, that question is worth exploring. There are approaches that work. Your nervous system wants to heal—it just needs the right support.

About the Author

Nadia Samuelsson|Trauma-Specialised Psychologist

Nadia Samuelsson is a trauma-specialised psychologist with expertise in Complex PTSD, attachment-based trauma, nervous system regulation, and relationship dynamics. She uses Somatic Experiencing, Emotion-Focused Therapy for Trauma (EFTT), EMDR, and Acceptance and Commitment Therapy, all with a trauma-informed, body-focused approach.

She works with adults dealing with the long-term eff ects of developmental trauma, childhood emotional neglect, complex PTSD, and the relationship patterns that follow. Her main focus is the nervous system—helping people understand their reactions and creating the right conditions for real, body-based healing.

Nadia regularly writes about trauma, Complex PTSD, attachment wounds, nervous system regulation, and relational healing. Her work is for people seeking to understand their own experiences of complex trauma.

Areas of Specialisation

• Trauma, PTSD, and Complex PTSD (C-PTSD)

• Attachment-based trauma and relational dynamics

• Childhood emotional neglect and developmental trauma

• Nervous system regulation and somatic approaches to trauma

• Emotion-Focused Therapy for Trauma (EFTT) and EMDR

• Burnout and chronic exhaustion rooted in trauma history

• People-pleasing, fawn response, and self-abandonment patterns

Continue reading: Part Two — "Complex PTSD: When the Wound Is the Relationship" — exploring relational trauma, emotional neglect, the 4F survival responses (fi ght, fl ight, freeze, fawn), and how healing works when the wound is not a single

episode but a way of being shaped.

Sources & Scientific Grounding

• Levine, P.A. — Somatic Experiencing: A New Paradigm; Waking the Tiger

• Herman, J.L. (1992) — Trauma and Recovery

• Van der Kolk, B. — The Body Keeps the Score

• Porges, S. — Polyvagal Theory

• World Health Organization ICD-11 — Code 6B40 (PTSD)

• Levy, D. (1946) — New York Hospital research on children's trauma responses