Many people who have experienced an accident or an assault tell me the same thing, with palpable shame: "I didn't react. I just froze. Why didn't I run, or fight back?"
This question deserves a clear scientific answer — not judgment.
Three strategies in the face of threat, not two
The fight-or-flight reflex is widely known. But Peter Levine, biophysicist and founder of Somatic Experiencing, identified a third defensive strategy, older on an evolutionary level: freeze, or tonic immobility.
In the face of extreme threat, when neither fighting nor fleeing is possible — because the attacker is stronger, because one is physically restrained, because the situation is too fast or too overwhelming — the nervous system activates this third option: complete immobilisation. The body literally "plays dead."
This mechanism has been extensively studied in the animal kingdom by psychologist Gordon Gallup, whose foundational 1977 research established tonic immobility as an innate defensive response to fear and predation. Researchers later studied its direct application to survivors of sexual assault: their study highlights that this type of trauma often involves the elements necessary to trigger tonic immobility in animals — fear and perceived physical restraint. In other words: freezing during an assault is not an absence of reaction. It is the activation of a defence mechanism millions of years old, shared with many animal species.
It is not a choice. It is a reflex.
As Levine himself explains: during fight-or-flight, all the muscles prepare for action, the heart rate accelerates, adrenaline floods the body. But if neither option is effective or possible, the nervous system automatically shifts into immobility. This is not a conscious decision. It is a survival reflex as old as the first vertebrates.
Why the body remains stuck afterwards
Here is the essential point for understanding the symptoms that persist after a shock: this freeze response is biologically designed to be time-limited. In wild animals, once the threat has passed, the massive energy mobilised for fighting or fleeing discharges — through trembling, shaking, a gradual return to movement. The animal "completes" its response.
But if this discharge phase cannot be fully accomplished, this charge remains trapped. And from the nervous system's perspective, the threat has never truly passed.
Stephen Porges, neuroscientist and creator of polyvagal theory, brought neuroanatomical precision to what Levine had been observing clinically for decades. The two researchers met in 1978, sharing a common interest in bodily processes. Porges demonstrated that this freeze response corresponds to the activation of a specific branch of the parasympathetic nervous system — the so-called "dorsal vagal" branch — which triggers a complete shutdown when the perceived threat is inescapable.
Why some animals don't develop trauma — and why humans do
A striking fact highlighted by Peter Levine in his clinical observations: wild animals living in natural conditions rarely develop chronic trauma, even though they regularly face threats. But humans — like some mammals in captivity — are often prevented from completing this defensive movement, and remain stuck either in hyperarousal or in immobility.
This is precisely what Somatic Experiencing works to resolve: not by reliving the event, but by allowing the body to finally and safely complete what the nervous system was unable to finish at the moment of the shock.
What this means for you
If you froze during an accident, an assault, or any other traumatic event, it was not a lack of courage. It was your nervous system activating, in a fraction of a second, the oldest and most powerful survival strategy it has available. This response likely protected you.
The problem is not that you froze. The problem is that this energy may never have had the chance to fully discharge. And this is precisely the work that Somatic Experiencing makes possible.
Do you recognise yourself in what you have just read? Book a first consultation.
Sources
- Levine, P.A. Interview — "Peter Levine on Trauma Healing: A Somatic Approach", Psychotherapy.net. Read the interview
- Somatic Experiencing International. SE 101. traumahealing.org/se-101
- Levine, P.A. Waking the Tiger: Healing Trauma. North Atlantic Books, 1997.
- Gallup Jr., G.G. (1977). Tonic immobility: The role of fear and predation. Psychological Record, 27, 41–61.
- Marx, B., Forsyth, J., Gallup Jr., G.G., Heidt, J.M., & Fuse, T. (2008). Tonic immobility as an evolved predator defense: Implications for sexual assault survivors. Clinical Psychology: Science and Practice, 15, 74–90.