Freeze is nature’s Plan C. It’s the program that initiates when there is no hope of escaping or fighting off a predator. If a prey animal is totally overwhelmed by a large predator, freeze makes a huge amount of sense. Predators tend to bite down a lot harder when they feel their prey struggle, and the freeze reflex overrides the instinct to fight or escape. If the predator believes the prey is dead, there is a reasonable chance that it will release its bite and open the possibility of escape. 

From one split second to the next, the limbic system weighs up all of the sensory inputs at fibreoptic shaming speeds and signals the body. Based on these signals sent down the spinal column and vagus nerve, the heart, lungs, muscles and glands either make good an escape, fight back, or freeze up.  

There are so many possible ways to escape if you freeze up in a predator interaction. Firstly freezing might mean the predator doesn’t manage to locate you. Then if you are caught, and you freeze, it amounts to playing dead. Playing dead means you don’t trigger the predator’s instincts to anything like the same level. Predators bite harder when there is a struggle. And the cat tends to lose a bit of interest in a mouse once it is dead. 

For many large predators, there is a time lapse between the instinct to kill and the instinct to eat. Big cats, for example, choose to wait until their body temperature and breathing have reduced before they start to eat. Social mammalian predators usually coordinate the pride, pack or offspring before they begin to eat their kill. Another time lag between kill and eat can arise when there are other predators competing for the kill.

All these potential time-lapses mean that if you had frozen up and ‘played possum’, thus avoiding the full neck bite, there is every chance a moment would arise when you could ‘unfreeze’ and make your escape. 

It is the failure of this freezing and ‘unfreezing’ mechanism that essentially causes trauma to get stuck in the human nervous system.

If you have ever felt an extreme shock that made your body go weak, then you know what the freeze feels like. The freeze reflex does not feel good. It sends the feeling of a horrible, cold, weak wave down your legs. It feels like wanting to escape but being totally weak and incapacitated. Countless victims of physical abuse have experienced the heartbreaking trauma of this. Many others among us have had far smaller tasters when we experience lesser sudden shocks to the system. 

There are two physical processes that must work to successfully unfreeze the freeze reflex and enable escape.

Firstly the muscles must unlock themselves; this involves shaking and trembling. When you see a person ‘in shock’ and they are shaking, what you are really seeing is them coming out of shock—the mechanism by which the freeze reflex releases involves shaking.

The second part of the process is the logical one. It’s going back to plan b and RUN.

In order for the nervous system to return to normal function after freezing, there needs to be plenty of shaking and running. Ideally followed by a nice, warm, appropriate feeling of safety back in the safety of the den or the herd. This is how the antelope returns to having a nice time after experiences the average human would take years to recover from.

Without the shaking and running, the freeze reflex is incomplete and remains unprocessed in the nervous system. Thus, it continues to behave as if there is still a threat. This is how we get traumatised and move forward ‘with trauma’ as opposed to ‘shaking off’ what happened and moving forward freely.

Having a large prefrontal cortex can be a real nuisance. The prefrontal cortex tends to take the paralysing and powerless shock of the freeze reflex very personally. Instead of surrendering and accepting it the way an antelope does, we have a tendency to both resist and personalise freeze. 

The freeze reflex is no more personal than the tendon hammer reflex in the knee. Yet through resistance and personalisation, we tend to incorporate the freeze experience into our sense of self. This is a big part of the reason why so many of us land in adulthood with a nagging feeling of powerlessness or vulnerability—having imprinted the identity that comes with being at our weakest when we most needed to be strong. 

The stress of a physical assault or simply being around an irritable, unpredictable adult for years on end are very difficult experiences. But they take on very different weight and meaning when there is a concurrent feeling of disempowerment.

The way our prefrontal faculties respond to adverse life events has left us extremely prone to ‘biting down’ on our nervous system’s freeze responses instead of releasing them in natural ways. Thus we are highly prone to the accumulation of unprocessed freeze reactions. This is what we refer to as trauma. And there are those who believe it is the single most destructive force we face as a species today.

There is some excellent news, however. The therapies that actually work for trauma, like EMDR and TRE,  easily tap into the limbic system and help release the unenacted shaking and ‘running’ reflexes over time. This has been shown to enable us to move on without the highly charged memories, hyper-vigilance and litany of other physical and mental impacts of unprocessed prey reflex.