Trauma and the Body: How Your Nervous System Responds to Overwhelm

Your Body Is Not Betraying You

If you live with the effects of trauma, you may have noticed that the past does not only live in your memory. It lives in the tightness across your shoulders. In the way your breath shortens when someone raises their voice. In the exhaustion that arrives without warning, or the numbness that descends when you need to feel most alive. You are not imagining this. You are not weak, and you are not broken.

Trauma is a whole-body experience. Long before we had the language to describe it, our nervous systems were quietly encoding every overwhelming moment as a survival lesson. The trembling hands, the frozen stillness, the heart that hammers at a smell or a sound — these are not overreactions. They are the body doing precisely what it learned to do to keep you safe.¹

This article explores what happens in the body and nervous system during and after trauma. We will look at the science behind the stress response, why trauma can become “stuck” in the body, the physical symptoms that often go unrecognised, and the body-based approaches that are helping people heal. Understanding why your body responds the way it does is often the first step towards befriending it again.

Please note: this article is intended as educational information. It does not replace assessment or treatment by a qualified mental health professional. If you are currently experiencing significant distress, please reach out to a therapist or your GP.

What Is the Nervous System, and Why Does It Matter?

The nervous system is the body’s communication network. It runs from your brain down your spinal cord and branches into every organ, muscle, and blood vessel. For our purposes, the most important part is the autonomic nervous system (ANS) — the part that operates below conscious awareness, regulating your heartbeat, digestion, breathing, and threat responses without you having to think about it.²

The ANS has two branches you have probably heard of. The sympathetic nervous system is the accelerator: it mobilises energy, speeds up the heart, and prepares you to act in response to threat. The parasympathetic nervous system is the brake: it promotes rest, digestion, connection, and recovery. In a healthy, regulated nervous system, these two systems work together in a fluid rhythm.

Trauma disrupts this rhythm. When the nervous system experiences something overwhelming, it can become stuck in a state of chronic activation — always scanning for danger, never fully settling into safety. Understanding this disruption is central to understanding why trauma affects the body so profoundly.

The Polyvagal Theory: A Ladder of Safety

One of the most significant developments in understanding trauma and the body comes from the work of neuroscientist Dr Stephen Porges, whose polyvagal theory describes three distinct states in the nervous system — each representing a different level of perceived safety.³

Imagine these states as rungs on a ladder. At the top rung, when we feel safe and connected, the ventral vagal system is engaged. We can think clearly, connect with others, be curious, laugh, and feel present. This is the state of social engagement, and it is where healing happens.

When threat is perceived, we descend the ladder. The sympathetic system activates, and we move into fight or flight — a state of mobilised, urgent energy. Heart rate increases, muscles tense, focus narrows. This state evolved to help us escape or confront danger, and it is brilliantly effective for that purpose.

When fight or flight fails — when escape is impossible, as it often is in situations of abuse, neglect, or overwhelming events — the nervous system descends to the third rung: the dorsal vagal state. This is the shutdown or freeze response. The body conserves energy, emotions flatten, sensation dims, and a person may feel numb, disconnected, or absent. This is what many people experiencing dissociation describe: a kind of stepping away from themselves or from the world.³

The polyvagal theory helps explain why people experiencing trauma do not always “snap out of it.” These are not choices. They are ancient, automatic survival responses. The nervous system is doing its best to protect you.

The Stress Response: Fight, Flight, and Freeze

When the brain perceives a threat — whether physical, emotional, or psychological — it triggers the hypothalamic-pituitary-adrenal (HPA) axis, a hormonal cascade that releases cortisol and adrenaline into the bloodstream.⁴ These stress hormones prepare the body for emergency action: pupils dilate, breathing quickens, digestion pauses, pain perception decreases, and blood is redirected away from non-essential functions towards the muscles.

In a short-lived threat, this is helpful. Once the danger passes, cortisol levels drop, the parasympathetic system reengages, and the body returns to equilibrium. You may feel shaky, tired, or tearful after the adrenaline fades — this is normal nervous system recovery.

In trauma, this completion does not happen. When a threat is inescapable, prolonged, or overwhelming, the stress response can become dysregulated. The body may stay in a state of high alert long after the danger has passed, or may swing between activation and shutdown. Research suggests that people who have experienced trauma show measurable differences in HPA axis functioning, cortisol regulation, and inflammatory markers — indicating that the physiological effects of trauma are real and lasting.⁴

The freeze response deserves particular attention. Often confused with calmness, freezing is an active survival state — the system is not relaxed, it is immobilised under extreme threat. Animals in the wild often shake or tremble after a freeze response, which appears to discharge the held energy from the nervous system. In humans, this natural completion is frequently suppressed — by social conditioning, shame, or the absence of safety.⁵ This suppression is thought to be one reason why trauma can become stored in the body rather than processed and released.

How Trauma Gets Stored in the Body

Psychiatrist Dr Bessel van der Kolk has spent decades studying how traumatic experience is encoded not just in memory, but in the body itself. His research — and his landmark book The Body Keeps the Score — describes how trauma can alter the way the brain processes sensation, emotion, and time, often leaving survivors feeling as though the past is perpetually present.¹

One key mechanism is the role of the amygdala, the brain’s threat-detection centre. In people who have experienced trauma, the amygdala can become hyperreactive, firing alarm signals in response to sensory cues that resemble the original threat — a raised voice, a particular smell, a specific time of year. These triggers can activate the body’s stress response before the thinking brain has had time to assess the situation.⁶

At the same time, the prefrontal cortex — responsible for rational thought, perspective, and calming the amygdala — becomes less active under extreme stress. This is why, in moments of overwhelm, it can feel impossible to “think your way through it.” The part of the brain that does the thinking is temporarily offline.⁶

Trauma may also affect the body at a cellular level. The Adverse Childhood Experiences (ACE) study, one of the largest investigations into the long-term effects of childhood trauma, found strong dose-response relationships between traumatic experiences in childhood and a wide range of physical health conditions in adulthood, including cardiovascular disease, autoimmune conditions, and chronic pain.⁷ The body, it seems, keeps the account.

Physical Symptoms of Trauma: What to Look For

Trauma manifests in the body in many ways, and these symptoms are often misunderstood or attributed to other causes. Recognising them as trauma responses can be an important step in getting the right support.

Common physical symptoms associated with trauma include:

• Chronic tension and pain: particularly in the jaw, neck, shoulders, back, or pelvis — areas where the body tends to hold protective tension
• Fatigue and exhaustion: the nervous system can be profoundly depleting when running in a state of chronic alert
• Hyperarousal: difficulty sleeping, exaggerated startle response, feeling constantly “on edge” or unable to relax
• Hypoarousal: feeling numb, flat, heavy, disconnected, or unable to feel emotions or physical sensations clearly
• Gastrointestinal symptoms: nausea, irritable bowel, loss of appetite, or digestive difficulty — the gut and the nervous system are deeply connected
• Dissociative symptoms: feeling detached from one’s body, environment, or sense of self (see below)
• Headaches and migraines
• Immune dysregulation: increased susceptibility to illness, or the development of autoimmune conditions
• Difficulty with physical touch: either hypersensitivity or a sense of numbness

It is important to have physical symptoms assessed medically to rule out other causes. However, if medical investigations return without explanation, or if symptoms cluster alongside a history of traumatic experience, it may be worth exploring a trauma-informed approach to treatment.⁸

Trauma, the Body, and Dissociation

One of the most significant body-level responses to overwhelming experience is dissociation: a disruption in the normally integrated functions of consciousness, memory, identity, and perception. When the body cannot escape a threat, the mind may create distance from the experience as a protective measure. This is why trauma and dissociation are so closely linked.⁹

From a polyvagal perspective, dissociation corresponds to the dorsal vagal shutdown state: the system has gone beyond fight or flight into a kind of protective disconnection. People may describe feeling “not in their body,” watching themselves from a distance, losing time, or finding that the world feels unreal or dreamlike.

These dissociative episodes are not a sign of psychological fragility — they are the nervous system deploying its deepest protective mechanism. Understanding this can help reduce the shame and confusion that often accompany dissociative experiences. The science behind how the brain produces these responses is explored in detail in our article on the neuroscience behind dissociation.

Body-based work — including somatic therapies, sensorimotor approaches, and nervous system regulation techniques — has shown particular promise in addressing the dissociative and physical symptoms of trauma, precisely because it works at the level where the trauma is held.⁵

Body-Based Approaches to Healing

If trauma is held in the body, then healing must involve the body. This is a growing consensus in trauma research and clinical practice. Below are some of the most evidence-informed body-based approaches, along with practical starting points you can explore with professional support.

Somatic Experiencing

Developed by Dr Peter Levine, Somatic Experiencing (SE) is a body-centred approach to trauma that focuses on tracking and completing the interrupted stress response. Rather than requiring the person to retell traumatic events in detail, SE works with the physical sensations associated with trauma — gradually titrating (introducing in small doses) the activation in the nervous system to allow it to discharge safely.⁵

In practice, an SE session might involve the therapist helping you notice where you feel tension or constriction in your body, and gently attending to those sensations without becoming overwhelmed. Over time, this can help the nervous system complete responses it was unable to finish during the original overwhelming event.

Sensorimotor Psychotherapy

Developed by Pat Ogden, sensorimotor psychotherapy integrates body awareness with psychological processing. It addresses the postures, movements, and physical impulses that become frozen in trauma, and works with the body to complete interrupted actions and restore a sense of agency.⁸

Trauma-Informed Yoga and Movement

Trauma-sensitive yoga practices — which emphasise choice, consent, and attention to internal sensation rather than performance — have been found in research to reduce symptoms of post-traumatic stress disorder (PTSD) and improve body awareness in trauma survivors.¹⁰ The emphasis on breath and present-moment sensation can help reconnect the person with their body in a gentle, manageable way.

Breathwork

The breath is one of the few bodily functions we can consciously regulate, and it has a direct influence on the autonomic nervous system. Slow, diaphragmatic breathing activates the parasympathetic system, reducing cortisol and heart rate. Even a few minutes of slow, extended exhales — longer than the inhale — can begin to shift the nervous system state.² This makes breathwork one of the most accessible self-regulation tools available, though it is worth noting that some trauma survivors find breath-focused practices activating rather than calming. If this is the case for you, movement-based approaches may be more accessible initially.

Grounding Practices

Grounding techniques work by bringing awareness back to the present-moment body and physical environment, which can interrupt states of hyperarousal or disconnection. Pressing your feet firmly into the floor, holding something cold or textured, noticing five things you can see — these simple practices work because they provide real-time sensory information to the nervous system, signalling that the present moment is not the threat.² These are explored in much greater depth in our article on grounding techniques for dissociation.

When to Seek Professional Support

Understanding trauma and the nervous system is valuable, but there are times when professional support is essential. Consider reaching out to your GP or a trauma-informed therapist if:

• Physical symptoms are significantly affecting your daily life, sleep, or functioning
• You experience frequent dissociative episodes, prolonged numbness, or depersonalisation/derealisation
• You are experiencing flashbacks, nightmares, or intrusive memories
• Emotional dysregulation — intense, sudden shifts in mood or feeling — is making relationships or work difficult
• You are using substances, self-harm, or other behaviours to manage overwhelming states
• You feel chronically exhausted in a way that rest does not resolve

Trauma-informed therapies with good evidence include Eye Movement Desensitisation and Reprocessing (EMDR), Trauma-Focused Cognitive Behavioural Therapy (TF-CBT), Somatic Experiencing, and sensorimotor psychotherapy. Your GP can provide a referral via NHS talking therapies, or you can explore private practitioners through directories such as the BACP or UKCP.

Further Reading

Books (Accessible to Beginners)

• van der Kolk, B. A. (2014). The Body Keeps the Score: Mind, Brain and Body in the Transformation of Trauma. Penguin. A foundational text, written for general readers, on how trauma reshapes the body and brain.
• Levine, P. A. (2010). In an Unspoken Voice: How the Body Releases Trauma and Restores Goodness. North Atlantic Books. Introduces Somatic Experiencing and the instinctual basis of trauma healing.
• Dana, D. (2018). The Polyvagal Theory in Therapy. W. W. Norton. An accessible guide to understanding nervous system states and using them in healing.

For More Advanced Reading

• Ogden, P., & Fisher, J. (2015). Sensorimotor Psychotherapy: Interventions for Trauma and Attachment. W. W. Norton.
• Porges, S. W. (2011). The Polyvagal Theory: Neurophysiological Foundations of Emotions, Attachment, Communication, and Self-Regulation. W. W. Norton.

Support Resources

• Mind UK: Trauma
• PODS (Positive Outcomes for Dissociative Survivors)

References

1. van der Kolk, B. A. (2014). The body keeps the score: Mind, brain and body in the transformation of trauma. Penguin.
2. Porges, S. W. (2007). The polyvagal perspective. Biological Psychology, 74(2), 116–143. https://doi.org/10.1016/j.biopsycho.2006.06.009
3. Porges, S. W. (2011). The polyvagal theory: Neurophysiological foundations of emotions, attachment, communication, and self-regulation. W. W. Norton.
4. McEwen, B. S. (2007). Physiology and neurobiology of stress and adaptation: Central role of the brain. Physiological Reviews, 87(3), 873–904. https://doi.org/10.1152/physrev.00041.2006
5. Levine, P. A. (2010). In an unspoken voice: How the body releases trauma and restores goodness. North Atlantic Books.
6. Yehuda, R., & LeDoux, J. (2007). Response variation following trauma: A translational neuroscience approach to understanding PTSD. Neuron, 56(1), 19–32. https://doi.org/10.1016/j.neuron.2007.09.006
7. Felitti, V. J., Anda, R. F., Nordenberg, D., Williamson, D. F., Spitz, A. M., Edwards, V., Koss, M. P., & Marks, J. S. (1998). Relationship of childhood abuse and household dysfunction to many of the leading causes of death in adults: The Adverse Childhood Experiences (ACE) study. American Journal of Preventive Medicine, 14(4), 245–258. https://doi.org/10.1016/s0749-3797(98)00017-8
8. Ogden, P., & Fisher, J. (2015). Sensorimotor psychotherapy: Interventions for trauma and attachment. W. W. Norton.
9. Brand, B. L., Lanius, R., Vermetten, E., Loewenstein, R. J., & Spiegel, D. (2012). Where are we going? An update on assessment, treatment, and neurobiological research in dissociative disorders as we move toward the DSM-5. Journal of Trauma & Dissociation, 13(1), 9–31. https://doi.org/10.1080/15299732.2011.620687
10. van der Kolk, B., Stone, L., West, J., Rhodes, A., Emerson, D., Suvak, M., & Spinazzola, J. (2014). Yoga as an adjunctive treatment for posttraumatic stress disorder: A randomised controlled trial. Journal of Clinical Psychiatry, 75(6), e559–e565. https://doi.org/10.4088/JCP.13m08561

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