Mental Floss

Why Do We Freeze When We’re Scared?

Freezing in dangerous situations may seem counterproductive, but your brain is just trying to help you.

If you ever freeze after hearing something go ‘bump’ in the night, you’re not alone.
If you ever freeze after hearing something go ‘bump’ in the night, you’re not alone. | Williams+Hirakawa/GettyImages

Picture how you might react if a stranger started harassing you on public transportation. Most people would, in theory, imagine telling them off, calling for help, or even physically defending themselves. However, in real life, finding that you can’t speak or even move to protect yourself is common. You might look away, make yourself smaller, or start to shake. After a few minutes, you may be able to think rationally again, but you’ll be plagued with the question: Why did I just stand there?

Coined in 1915 by physiologist Walter Bradford Cannon, the phrase fight or flight describes two core instincts that animals (including humans) can have when perceiving a threat: to fight or to run away. Fight and flight are now well-known, but a third reaction— to freeze—is still misunderstood by many.

The freeze response affects people of all kinds, but it only started getting significant attention in the 1970s, when psychologist Gordon G. Gallup Jr. equated tonic immobility—the freezing of animals in response to a predator—with a response to fear.

  1. What makes us freeze?
  2. Can we stop freezing?

What makes us freeze?

When you feel threatened, a chain reaction begins in your brain. The amygdala, which is responsible for perceiving fear, sends a signal to the hypothalamus, which regulates your body and brain chemistry. The hypothalamus then stimulates the adrenal glands to release stress hormones like adrenaline. This triggers two parts of your autonomic (involuntary) nervous system: the sympathetic and parasympathetic nervous systems. One overpowers the other, and this dictates your response.

The sympathetic nervous system controls action. When this system is dominant, it can feel like a burst of energy directing you either toward the threat or away from it a.k.a. fight or flight. The parasympathetic nervous system does the opposite. Its role is to help you to calm down and recover once the threat has passed—so when this system is dominant, it keeps you still. In other words: You freeze.

In a freeze response, your brain and body are working to evaluate the threat. This is the instinctual equivalent of pressing pause or taking a deep breath before you act. Your hearing gets sharper so that you can perceive your surroundings more clearly; your heart rate and breathing slow down to conserve energy; pain is distracting, so your perception of pain often decreases.

All this happens in a split second, before your “thinking brain” gets involved and starts to analyze the situation more rationally. You’re not thinking clearly in this moment because fight, flight, and freeze are reflexes governed by a part of the brain that evolved to protect you from predators. Freezing is a response you cannot control—not a deliberate choice to do nothing.

Can we stop freezing?

Anyone can experience a freeze response, but people with a history of childhood trauma or anxiety are more prone to it. In 2024, researchers at Tulane University reported a new chemical pathway in the brains of mice that may govern the shift from the freeze response to the flight response. The finding could help scientists understand this shift in the more complex human brain, which could further the research into treating and understanding trauma-induced conditions, like PTSD. If it is possible to change our fear response, this could lead to breakthroughs in mental health therapy.

We may not (yet) be able to consciously stop freezing, but we can work on keeping our brains from going into any reflexive fear response when one isn’t needed. Fight, flight, and freeze are not always triggered by real danger; sometimes just thinking about a stressful situation can be enough, as the amygdala perceives this as life-threatening.

If you think—as many do—that freezing up is a personal failing, the resulting guilt and frustration can make you more stressed. Just understanding the science of the freeze response can help us to process what is going on in our bodies, and understanding the reaction is the first step to recognizing and coming out of “freeze mode.”

Freezing might not seem logical to your thinking brain, but your amygdala is not logical—and it really is trying to help you.

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