Have you ever wondered why your body still reacts as though something bad is about to happen, even when you know you are safe?

Maybe a sound makes your heart race. A particular smell brings back a memory. You find yourself constantly scanning your surroundings or feeling tense without knowing why.

For some people, these reactions develop after experiencing a traumatic event.

Trauma can affect how we think, feel and respond to the world around us. Understanding why these reactions occur can be an important part of making sense of what is happening.

Consider John, a fictional example.

John was involved in a serious motor vehicle accident. Although he recovered physically, he noticed that driving became increasingly difficult.

When another vehicle approached an intersection quickly, his body reacted immediately. His heart raced, his muscles tightened and he felt an urge to brake or move away.

Intellectually, John knew he was not back at the original accident.

But his body was responding to cues that had become associated with danger.

What Do We Mean by Trauma?

The word “trauma” is used in different ways.

In everyday conversation, people may use it broadly to describe experiences that were extremely distressing, overwhelming or emotionally painful.

In clinical settings, however, conditions such as post-traumatic stress disorder (PTSD) have more specific criteria.

For PTSD, traumatic exposure involves death, threatened death, actual or threatened serious injury, or actual or threatened sexual violence through particular forms of exposure.

This distinction does not mean other painful experiences are unimportant. Experiences that do not meet formal PTSD trauma criteria can still have significant psychological effects and may warrant support.

It does mean that not every highly stressful or distressing experience should automatically be described as a traumatic event in the diagnostic sense.

Medical Trauma

Serious illness, injury and medical treatment can sometimes involve traumatic exposure.

Examples may include: a serious motor vehicle accident; life-threatening illness or injury; emergency medical treatment following severe injury; serious complications during childbirth; or witnessing severe injury or death.

Medical environments can also become associated with fear following a frightening experience.

For example, a person who underwent emergency treatment after a serious accident may later notice anxiety when returning to a hospital, hearing medical equipment or encountering other reminders of the event.

Whether an experience meets formal PTSD exposure criteria depends on the nature of what occurred rather than simply whether the experience happened in a medical setting.

Psychological and Interpersonal Experiences

People can experience significant psychological harm through interpersonal experiences such as abuse, coercion, violence, neglect, loss and relationship breakdown.

Some interpersonal experiences—such as physical violence or sexual violence—may meet PTSD trauma criteria.

Others may be deeply distressing without meeting those specific diagnostic criteria.

The psychological impact of an experience is still important regardless of whether a particular diagnosis applies.

Occupational and Emergency-Service Exposure

Some occupations involve a greater likelihood of repeated exposure to traumatic events.

This can include: paramedics; firefighters; police officers; defence personnel; emergency department staff; and other workers regularly exposed to serious injury, death or traumatic material.

Research has found elevated rates of trauma-related difficulties in rescue workers and other occupations with repeated exposure to traumatic events (Berger et al., 2012; Cieslak et al., 2014).

People can also experience moral injury when they perpetrate, fail to prevent, witness or learn about acts that transgress deeply held moral beliefs and expectations. Moral injury overlaps with trauma-related difficulties but is not itself a psychiatric diagnosis (Litz et al., 2009).

Cumulative Exposure

Not all trauma-related difficulties arise from a single event.

For some people, repeated exposure to traumatic events can accumulate over time. This may be particularly relevant in occupations where exposure to serious injury, death, violence or traumatic material is part of the work (Cieslak et al., 2014).

Someone may cope effectively with many incidents before noticing that particular events begin to replay in their mind, certain cues trigger strong reactions, or their general level of alertness has increased.

It is important to distinguish this from ordinary cumulative stress. Repeated stress and pressure can have significant effects on wellbeing, but they do not necessarily meet the exposure criteria for PTSD.

What Happens in the Brain and Body?

Trauma-related disorders involve more than conscious memory. They can affect systems involved in learning, memory, attention, emotion and physiological stress regulation (Dalvie & Daskalakis, 2021).

The amygdala, hippocampus and prefrontal regions are often discussed in trauma research because they form part of interacting networks involved in threat detection, memory and regulation (Dalvie & Daskalakis, 2021).

These regions should not be thought of as simple individual switches or as necessarily being permanently damaged by trauma.

Instead, trauma-related symptoms appear to involve changes across interacting neural and physiological systems.

This can help explain why someone may consciously know they are safe while still experiencing a rapid physical or emotional response to a reminder of what happened.

Trauma and post-traumatic stress symptoms have also been associated with physical health outcomes, although the relationships are complex and influenced by many factors (Schnurr & Green, 2004; Sumner et al., 2023).

Psychological and Social Effects

Trauma-related difficulties can affect more than fear.

People may experience: intrusive memories or nightmares; avoidance of reminders; feeling constantly alert or easily startled; irritability; sleep difficulties; difficulty concentrating; emotional numbness; changes in mood or beliefs; or feeling disconnected from others.

Trauma can also affect relationships and social functioning (Monson et al., 2009; Schnurr & Green, 2004).

Some people withdraw because they do not want to burden others. Others may find it difficult to explain why they are reacting differently.

Partners and family members may also struggle to understand why someone seems distant, irritable or constantly on guard.

A Nautical Way of Understanding Trauma

Imagine being caught in a severe storm at sea.

During the storm, you become highly alert to changes in the wind, the movement of the water and anything that might signal danger.

That alertness is useful while the storm is occurring.

Eventually, the storm passes.

But afterwards, you may find yourself reacting strongly whenever the wind begins to rise or the water becomes rough.

The conditions are not necessarily the same as the original storm, but your mind and body have learned that particular cues can signal danger.

Trauma-related responses can work in a similar way.

Sounds, smells, places, sensations or situations associated with a traumatic event can later trigger a strong response even when the person consciously understands that the original danger is no longer present.

The aim of recovery is not to forget that the storm happened.

It is to help the mind and body learn that reminders of the storm do not always mean another storm is occurring now.

Signs That Additional Support May Be Helpful

It may be worth seeking professional support if trauma-related reactions are: persisting over time; interfering with sleep; affecting work or relationships; leading you to avoid important parts of your life; causing significant distress; contributing to alcohol or other substance use; or making it difficult to feel safe even in relatively safe situations.

Not everyone who experiences a traumatic event develops PTSD, and people can recover in different ways.

Looking at the Whole Person

Trauma does not occur in isolation from the rest of someone’s life.

A biopsychosocial approach considers biological, psychological and social factors together.

This can include physical health, sleep, previous experiences, coping strategies, relationships, workplace demands, social support and the meaning someone makes of what happened.

Understanding these factors can help guide treatment and recovery.

What Can Treatment Involve?

For adults with PTSD, current clinical guidelines place the strongest emphasis on trauma-focused psychological treatments, including cognitive behavioural therapy approaches, Cognitive Processing Therapy and Prolonged Exposure (American Psychological Association, 2025).

EMDR is also supported as a treatment for PTSD, although the strength of recommendations differs across guidelines.

Other strategies may be used alongside trauma-focused treatment depending on the person’s needs.

These may include: psychoeducation about trauma responses; skills for managing strong emotional or physiological reactions; grounding strategies; sleep interventions; addressing avoidance; rebuilding routines and social connection; and treatment for co-occurring anxiety, depression or substance use when relevant.

Other approaches sometimes described as somatic, body-based, schema-focused or biofeedback-based may be useful for some people or particular difficulties, but they should not automatically be presented as having the same evidence base as established first-line PTSD treatments.

Treatment should be tailored to the individual, their symptoms, preferences and circumstances.

When Should I Seek Help?

If memories, nightmares, avoidance, hypervigilance or other trauma-related reactions are continuing to interfere with everyday life, professional support may be helpful.

Seeking support does not require waiting until symptoms become severe.

A mental health professional can help assess what is happening, determine whether symptoms are consistent with PTSD or another difficulty, and discuss appropriate treatment options.

For people working in emergency services, healthcare, defence or other high-exposure occupations, it can also be useful to recognise that repeated exposure to traumatic events can have an impact even when responding to these situations is part of the job.

Final Thoughts

The danger may have passed, but the brain and body can continue responding to reminders of what happened.

These reactions can make sense when understood as part of learning, memory and the body’s systems for responding to threat.

Recovery is not about pretending the experience did not happen.

It is about helping the person respond differently to memories and reminders so that past danger does not continue to dominate the present.

References

American Psychological Association. (2025). Clinical practice guideline for the treatment of posttraumatic stress disorder (PTSD) in adults.

Berger, W., Coutinho, E. S. F., Figueira, I., Marques-Portella, C., Luz, M. P., Neylan, T. C., Marmar, C. R., & Mendlowicz, M. V. (2012). Rescuers at risk: A systematic review and meta-regression analysis of the worldwide current prevalence and correlates of PTSD in rescue workers. Social Psychiatry and Psychiatric Epidemiology, 47(6), 1001–1011. DOI: 10.1007/s00127-011-0408-2

Cieslak, R., Anderson, V., Bock, J., Moore, B. A., Peterson, A. L., & Benight, C. C. (2014). Secondary traumatic stress among mental health providers working with the military: Prevalence and its work- and exposure-related correlates. Journal of Nervous and Mental Disease, 201(11), 917–925. DOI: 10.1097/NMD.0000000000000034

Dalvie, S., & Daskalakis, N. P. (2021). The biological effects of trauma. Complex Psychiatry, 7(1–2), 10–20. DOI: 10.1159/000517236

Litz, B. T., Stein, N., Delaney, E., Lebowitz, L., Nash, W. P., Silva, C., & Maguen, S. (2009). Moral injury and moral repair in war veterans: A preliminary model and intervention strategy. Clinical Psychology Review, 29(8), 695–706. DOI: 10.1016/j.cpr.2009.07.003

Monson, C. M., Taft, C. T., & Fredman, S. J. (2009). Military-related PTSD and intimate relationships: From description to theory-driven research and intervention development. Clinical Psychology Review, 29(8), 707–714. DOI: 10.1016/j.cpr.2009.09.002

Schnurr, P. P., & Green, B. L. (2004). Understanding relationships among trauma, post-traumatic stress disorder, and health outcomes. Advances in Mind-Body Medicine, 20(1), 18–29.

Sumner, J. A., Kubzansky, L. D., Roberts, A. L., Gilsanz, P., Chen, Q., Winning, A., Rimm, E. B., & Koenen, K. C. (2023). Posttraumatic stress disorder symptoms and cardiovascular disease risk: A longitudinal investigation. Translational Psychiatry, 13, 51. DOI: 10.1038/s41398-023-02330-8