Polyvagal Theory: What It Claims and Where Scientists Disagree

What Is Polyvagal Theory in Simple Terms?

In simple terms, polyvagal theory is about safety and danger. According to the theory, when you sense danger, your nervous system switches to fight or flight. You become on edge and prepare for attack. This state is tiring and can only be sustained for so long. When the body stays there too long, or is pushed even further, a freeze response can follow as everything starts to shut down. When you perceive safety, a part of the nervous system linked with enjoying life with friends and family becomes active. The theory calls this the social engagement system. Trauma and PTSD can make it harder to reach, especially for people with complex trauma (C-PTSD) who grew up used to nervous system dysregulation.

It is natural to think that progress comes from pushing yourself, but progress often comes from staying within your window of tolerance. Pairing a sense of safety with experiences that used to be triggering, and keeping that sense of safety, can help healing, even though it can feel counterintuitive.

Not all stress is bad. Problems such as trauma and dissociation can arise when stress is chronic and overwhelming, again and again.

The States of the Nervous System

Polyvagal theory describes three parts of the nervous system, rather than only the sympathetic and parasympathetic systems often taught in school:

• Ventral vagal system (social engagement). In situations perceived as safe, the ventral vagal system promotes social engagement, connection and feelings of wellbeing.
• Sympathetic nervous system (fight or flight). When faced with a threat, the sympathetic nervous system activates, preparing the body for fight or flight by increasing heart rate, mobilising energy and heightening awareness.
• Dorsal vagal system (freeze). If a situation is perceived as overwhelming or inescapable, the dorsal vagal system may activate, leading to a “freeze” response marked by shutdown, dissociation or disconnection.

What Is the Controversy over Polyvagal Theory?

Polyvagal theory is a model, not settled science. In a 2023 review, the psychophysiologist Paul Grossman argued that the theory’s five basic premises are untenable or highly implausible (Grossman, 2023). A 2026 paper by 39 experts on the vagus nerve and its evolution concluded that the theory’s main premises are not supported by current evidence (Grossman and colleagues, 2026). The ideas on this page are offered as a way of describing nervous system states, not as established fact.

How These Ideas Are Used in Sessions

Sessions draw on ideas about the nervous system, including polyvagal theory, in how therapy is paced and structured. Emotional reactions, anxiety, shutdown or dissociation are not treated as problems to be eliminated. They are understood as signals of a nervous system that has learned to protect you.

Many people experiencing C-PTSD, trauma-related depression or chronic anxiety believe something is fundamentally wrong with them. These symptoms can instead be understood as the nervous system doing what it learned to do in response to earlier conditions. The task of therapy is not to override these responses, but to help the nervous system gradually update, so it can respond to the present rather than remain organised around the past.

Rather than pushing insight or emotional exposure faster than your nervous system can tolerate, therapy is paced to support regulation and stability. This may include grounding practices, attention to bodily responses, and body-based or somatic approaches that help restore a sense of safety and orientation. Working this way aims to reduce the risk of overwhelm, collapse and retraumatisation.

In sessions, the focus may be on noticing how your body responds, not only what you think. You learn to track when the nervous system shifts into fight, flight or shutdown, and how to restore a sense of grounded presence before engaging with difficult material. Over time, this can build the capacity to stay emotionally engaged without becoming flooded or numb. As regulation improves, thoughts may become clearer, emotions more accessible and relationships less reactive.

Who This Approach Is For

This approach can be particularly helpful for people who understand their difficulties intellectually but still feel stuck. It can also suit people who experience anxiety, emotional overwhelm or chronic tension, or who feel emotionally numb, detached or shut down. The same goes for people with a history of complex trauma, developmental stress or relational injury.

It may also suit people who find that traditional talk therapy alone has felt limited or ineffective, especially with C-PTSD, trauma-related depression or nervous system-based symptoms that do not respond to insight alone.

How This Integrates with Other Therapeutic Approaches

Awareness of the nervous system is not a standalone technique. It is used alongside other approaches, including somatic work, parts work (IFS), cognitive behavioural therapy (CBT) and narrative therapy.

When the nervous system is more regulated, trauma processing may feel safer, cognitive work may land more deeply and emotional insight may lead to real change rather than repetition. Therapy can then move forward without relying on force or urgency.