What is Polyvagal Theory
Written by: THE BALANCE
Medically reviewed by Dr. Sarah Boss, MD
Last updated: January 19, 2026
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Quick Summary
  • These advancements bring new theories and approaches to how we understand our brain and body.
  • Stephen Porges, a Psychologist and Neuroscientist who coined The Polyvagal Theory.
  • At the heart of his theory is the relationship between our nervous system and emotional regulation.

The past few decades have seen huge advancements in mental health treatment. These advancements bring new theories and approaches to how we understand our brain and body. One of the more recent advancements comes from Dr. Stephen Porges, a Psychologist and Neuroscientist who coined The Polyvagal Theory. At the heart of his theory is the relationship between our nervous system and emotional regulation. It is his belief that it is our nervous system that affects our emotions, not the mind. Dr. Porges has been one of the many people in the mental health field who has inspired our clinical director, Dr. Sarah Boss, in her own work. To understand this theory more, we sat down with Dr. Boss to discuss what it is, why it matters, and how it informs her work as a psychiatrist and psychologist.

At its core, the Polyvagal Theory explores the complexities of our nervous system and how it relates to our emotional regulation. In our body, autonomic nervous system (ANS), which controls bodily functions like heart rate, digestion, and respiratory rate. The polyvagal theory suggests that there is more to the ANS that just our our binary response of ‘fight or flight’ (sympathetic nervous system) and ‘rest and digest’ (parasympathetic nervous system). Instead, it introduces a third, critical component: the social engagement system. This is a hybrid form of the nervous system that is alive when we engage with people. In his understanding, the ANS is constantly scanning surroundings for sign of safety or threat. He called this neuroception.

Dr. Porges’ theory focuses on the vagus nerve, also known as the tenth cranial nerve, is the longest and most complex of the cranial nerves. It extends from the brainstem, down through the neck and into the chest and abdomen. The name “vagus” comes from the Latin word for “wandering,” reflecting the nerve’s extensive path through the body. The Polyvagal Theory emphasises the role of the vagus nerve on the nervous system and looks at how it affects the heart, lungs, and digestive tract. The vagus nerve has two branches:

  1. Dorsal Vagal Complex (DVC): This is the more primitive part of the vagus nerve, responsible for the ‘freeze’ response in the face of extreme stress. When overactivated, it can lead to shutdown, dissociation, and a sense of helplessness.
  2. Ventral Vagal Complex (VVC): This is the more evolved part of the vagus nerve, involved in social communication and emotional regulation. It supports calming and self-soothing behaviors, enabling social interactions and emotional connections.

The evolution of mental health treatment has shifted from a focus on the brain, to a a more holistic look at the whole Being. With the Polyvagal Theory, this couldn’t be more true. PVT emphasises using somatic experiencing, things that can calm and ground us. It focuses on the body, the breathing, the vibrations. It can’t just be talking that heals us. Dr. Boss explains: “This is inherent to animals and mothers. A baby cannot regulate itself. We co-regulate with rocking, humming, and the vibration of the chest. We see the issue, and we instinctively know what to do. That’s vagus nerve stimulation. This is what being a good therapist should be about: co-regulated a patient. And that regulation can only happen if we are regulated ourselves.”

At The Balance, the nervous system is incorporated into everything we do. We don’t separate the brain and body as if they were not one. Dr. Boss notes: “At least 80% of the vagus nerve is bottom-up, it gives information from the body to the brain. Only 20% goes down, maybe even less. That means that our body, our physiology is so important.” She goes on: “Everything is so cognitive today. People are disassociated. They don’t notice their own body anymore. They feel pain, hunger, and thirst.” This is why at The Balance, we don’t isolate treatments. The care you receive is always inter-connected. Therapy treatments include nervous system regulation; they include the body in the work and vice versa. Somatic experiences don’t factor out the mind. That is why our treatment Program include a wide variety of techniques that account for this unique interplay. We aim to bring the body to safety so that a client can finally begin to heal.

The Polyvagal Theory is one of the most recent frameworks in mental health treatment that focuses on the relationship between our nervous system and our ability to regulate emotionally. Dr. Porges’ theory focuses on the vagus nerve, also known as the tenth cranial nerve, the longest and most complex of the cranial nerves. Porges proposes a third part of our autonomic nervous system that involves how we feel in our social engagement. We are constantly scanning our surroundings for signs of threat or safety, and this can be perceived in the most simple of facial expressions or body language. We as humans have the ability to connect: nervous system to the nervous system. This ability is vital to how we should approach mental health treatment. Safety is not just something that can spoken into, but rather an instinctual process that we are all born with. We can ground each other in the present as people and as therapists working with patients. This theory is at the core of what we do here at The Balance.

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