Is the freeze response a form of hyperarousal or hypoarousal?

When faced with a threatening or overwhelming situation, humans and animals have evolved a set of survival responses. While the "fight or flight" reactions are widely recognized, there is another critical response often overlooked—the freeze response. This response, characterized by an inability to move or take action, is unique interplay between hyper-arousal and hypo-arousal, involving both the sympathetic and parasympathetic nervous systems.

The Freeze Response Explained

The freeze response is an involuntary reaction that occurs when an individual feels extremely threatened and perceives escape or defense as impossible. It is akin to an animal playing dead when caught by a predator; an instinctual attempt to avoid detection or harm. This state of immobility can be brief or prolonged and is often accompanied by a sense of numbness or disconnect from the environment.

The Neurological Mechanism: Sympathetic and Parasympathetic Involvement

To understand the interplay between hyper-arousal and hypo-arousal in the freeze response, we must understand the roles of the autonomic nervous system's two main branches: the sympathetic and parasympathetic nervous systems.

• Sympathetic Nervous System (SNS): Responsible for the "fight or flight" responses, the SNS prepares the body for rapid action by increasing heart rate, dilating pupils, and releasing adrenaline. This state is commonly referred to as hyper-arousal.

• Parasympathetic Nervous System (PNS): The PNS promotes rest and digestion, slowing down the heart rate and conserving energy. Activation of the PNS leads to a state of hypo-arousal, characterized by reduced physiological activity and a calming effect on the body.

Freeze Response: A Blend of Hyper- and Hypo-Arousal

Interestingly, the freeze response involves a simultaneous activation of both the SNS and PNS, making it a unique phenomenon that does not fit neatly into the categories of hyper-arousal or hypo-arousal. According to research published in the Journal of Neuropsychiatry and Clinical Neurosciences, the freeze response begins with a surge of SNS activity, akin to preparing for fight or flight. However, when escape seems impossible, the PNS kicks in, leading to a state of immobility and dissociation.

This dual activation creates a physiological paradox where the body is highly aroused internally (hyper-arousal) yet externally appears calm and still (hypo-arousal). Polyvagal Theory, developed by Dr. Stephen Porges, further elucidates this mechanism, suggesting that the freeze response is mediated by the vagus nerve which regulates both the SNS and PNS. This theory posits that the freeze response is an adaptive strategy to enhance survival by reducing metabolic demands and minimizing the likelihood of being detected by a predator.

Examples of the Freeze Response

1. Animal Behavior: A classic example is "tonic immobility" observed in animals like rabbits and deer. When caught by a predator, these animals often remain motionless, a survival tactic that can sometimes dissuade the predator from attacking.

2. Human Trauma Response: In humans, the freeze response can manifest during traumatic events such as assaults or accidents. Survivors often report feeling paralyzed or disconnected during the event, a state that can persist even when the danger has passed .

3. Social Situations: The freeze response is not limited to physical threats. In socially overwhelming situations, individuals might experience a "deer in the headlights" moment, where they feel unable to speak or move.

Research and Implications

Research by Ledoux and Gorman (2001) highlights the complexity of the freeze response, suggesting that it is a protective mechanism that helps individuals manage extreme stress. In therapeutic settings, understanding the freeze response is essential for treating conditions like post-traumatic stress disorder (PTSD), where individuals may experience chronic immobility and dissociation as lingering effects of trauma.

A study published in Journal of Neuropsychiatry and Clinical Neurosciences underscores the importance of recognizing the freeze response in clinical practice. The researchers argue that effective trauma therapy should address both the physiological and psychological aspects of this response, helping individuals to reintegrate and move beyond their immobilization (Schauer, M & Elbert, 2010).

Conclusion

The freeze response is a sophisticated survival mechanism that embodies elements of both hyper-arousal and hypo-arousal. By engaging both the sympathetic and parasympathetic nervous systems, it creates a state of high internal alertness while externally appearing still and immobile. Recognizing and understanding this response is essential for both clinicians and individuals, particularly in the context of trauma recovery, where addressing the freeze response plays an important role in trauma integration.

References

1. Ledoux, J. E., & Gorman, J. M. (2001). A Call to Action: Overcoming Anxiety Through Active Coping. Nature Reviews Neuroscience, 2(2), 121-130.

2. Porges, S. W. (2007). The Polyvagal Perspective. Biological Psychology, 74(2), 116-143.

3. Roelofs, K. (2017). Freeze for Action: Neurobiological Mechanisms in Animal and Human Freezing. Philosophical Transactions of the Royal Society B: Biological Sciences, 372(1718), 20160206.

4. Schauer, M., & Elbert, T. (2010). Dissociation Following Traumatic Stress: Etiology and Treatment. Journal of Neuropsychiatry and Clinical Neurosciences, 22(4), 408-412.

5. Wessel, I., & Merckelbach, H. (1997). The Impact of Tonic Immobility on Perceived Memory Quality. Psychological Research, 60(2-3), 185-190