While trauma is a word used to describe a range of dysfunctional individual or collective experiences, it is normally defined in two distinct categories – single-shock trauma, whereby an individual experiences a sudden and immense threat to survival; or developmental trauma, whereby the physiological development of the child is impaired by a distorted perception of self and other.

To more fully understand trauma and its physiological causes, we must understand something of the human nervous system. In human beings the Autonomic Nervous System, part of the Peripheral Nervous System that operates in addition to the Central Nervous System, is responsible for regulating physiological response to the environment. The ANS is split into two parts as are our emotional selves – the sympathetic nervous system (sym pathos meaning literally ‘with feeling’) manages ‘going up’ expressive energies such as anger, fear, joy and excitement that involve movement towards or away from an object; while the parasympathetic system manages ‘going down’ emotions of yielding and collapse such as shame, guilt, despair, contentment and satisfaction that saturate the subjective physiological state of the body system. What is important to note is that these two systems work in tandem – the ‘going up’ SNS expresses and releases intense affect while the ‘going down’ PrNS permeates the body with it and there is a cohabitation and often a conflict between the two.

Crucially in regards to trauma and dissociation, the ANS is also responsible for triggering the body’s physiological response to threat and danger. Both sides of the ANS are able to respond and depending on the individual conditioning and the extremity of the situation depends on what side gets activated. In tolerable situations, where the individual can internally manage the immense fear and anxiety, the sympathetic system will trigger and utilize a fight or flight response as adrenaline is released and the body becomes charged for action. This allows for immediate expression.

The PrNS, however, operates by immobilization, which can manifest as freezing or fainting. This is when the system completely shuts down as a behavioural response to threats that are perceived to be inescapable. This immobilization happens when the right cortex of the brain becomes overwhelmed as a result of stimulus that cannot be contained or effectively processed, and the left dampens regulatory processing by preventing it from accessing conscious awareness. These would be because more powerful affects, such as terror, horror or rage are coursing through the physiological system. Peter Levine uses the example of an impala being chased by a cheetah to demonstrate the freeze reflex. As the cheetah pounces, through instinct the impala has entered an altered state of consciousness and surrendered to its impending death. The system has effectively ‘inhibited’ or blocked the extreme affect it is experiencing because it is too intense. This is an ‘interrupted impulse’, whereby the vaso-motoric cycle towards expression, discharge and relaxation has not been completed and the re-balancing of the SNS and PrNS systems cannot take place.

What happens with conditions such as Post Traumatic Stress Disorder, is that because the powerful emotional affect has been dampened down and not brought into awareness for conscious association, the affect subconsciously remains within the physiological system. The individual is chronically stuck in an event because the physiological fight-flight and freeze responses are consistently triggered by the body’s neurotransmitters long after the original threat has passed and been survived. This is normally because the physiological regulation mechanism has been previously damaged – clients presenting PTSD from single-shock traumatic events almost always to some extent display evidence of developmental trauma.

Working with the effects of trauma in the therapy room can often require a two-fold approach, one focusing on the sensory motor triggers, utilising techniques such as Eye Movement Desensitisation Reprocessing, with the other focusing on the issues surrounding the developmental deficits that have left the affect regulatory system compromised in its ability to deal with and process traumatic experience.


Some useful resources and articles surrounding PTSD and provided by Mental Wellness Center are as follows:

Taking Control of Your Trauma: A Guide to PTSD Treatment – ‘this not only has great general information about this mental health disorder, but it also sheds light on the many treatment options available for those struggling with it.’

Why Women Have Higher Rates of PTSD Than Men – ‘a lot of people picture men when envisioning someone with PTSD, but the truth is more women struggle with it. Thankfully, there are many ways for them to seek help.’

PTSD in Children — Does Your Child Have Symptoms? – ‘sadly, many children are affected by PTSD (this article notes that an estimated “60 percent of children who survive disasters” develop it, among others). This resource will help concerned parents find help for their children.’

Promoting Mental Health at Home: How to Design the Perfect Meditation Room – ‘many people with PTSD have told me that along with therapy, meditation and yoga are both wonderful ways to ease their symptoms. It’s really easy to create a calming space for practicing both at home.’

So, You Want a PTSD Service Dog? – ‘man’s best friend is quickly becoming a renowned source of support for those with PTSD (as well as many other mental health issues). This great article has answers for anyone with questions about getting one of these special creatures for themselves or a loved one.’

Maryville University also provides an interesting breakdown of PTSD in a military context here.

SingleCare also provide a useful overview of PTSD here.

Web Resources

Trauma Healing

Trauma Pages


European Society for Trauma and Dissociation