Polyvagal Theory


The vagus nerve

  • The vagus it is a conduit cable that connects our body with our brain.
  • The vagus nerve is the 10th cranial nerve that exits from the brain-stem goes to many of our organs.
  • It is the largest nerve that travels throughout the body.
  • Think of the vagus as a thick electrical cable where 80% of its fibres are sensory sending information from the organs to the brain.

The vagus is the portal to the brain, face, eyes, ears, heart and lungs from the periphery of the body and is constantly sending us information about what feels safe.

It regulates organs above and below the diaphragm and communicates the status of these primary organs. When you feel good the vagus conveys that you are in a good state, when you feel bad (such as nausea) it conveys that too.

The definition of the word vagus is ‘wandering’ and it wanders through our body via two main branches.

  • The ventral branch above the diaphragm is myelinated (has a protective sheath of fat which means it sends messages quickly)
  • and the dorsal branch which is mainly below the diaphragm and is unmyelinated (works slowly)

We understand that mammals come from reptiles, but we now know that our neural circuits have adapted to create the mammalian ventral vagal pathway which is located above the diaphragm.

This is linked to the nerves that regulate the heart, lungs, face, neck and head (face, eyes & ears). This means that the breath, heart rate, face, eyes, ears and neck become a portal to help us view health AND emotional wellbeing.

A flat and unresponsive face often indicates a lack of emotional connection and wellbeing and might indicate that the dorsal vagal (freeze/shutdown) response is dominating the system. This is not the optimal zone for any kind treatment to work effectively.

Understanding Vagal Tone

Vagal tone is a clinical measurement that is calculated by tracking breathing rate alongside heart rate. The greater the difference between inhalation heart rate and exhalation heart rate the higher the vagal tone.

When vagal tone is high, this means the body can regulate quickly after experiencing a stressful incident. This means that blood glucose levels are more regulated which reduces the likelihood of stroke, cardiovascular disease and diabetes.

Low vagal tone has been connected to increased, chronic inflammation and serious disease.


Developed by Dr Stephen Porges, polyvagal theory explains the vital importance of the vagus nerve in our understanding of trauma, and how to effectively treat it.

Prior to his discovery we used to think that the nervous system had two main responses – activation and relaxation.

Porges discovered that we actually have three well defined neural circuits that follow our evolutionary history. These circuits support:

  • Social engagement ‘feeling safe and happy to connect’ (ventral vagal responses)
  • Mobilisation (fight/flight/excitement – taking action)
  • Immobilisation (dorsal vagal freeze & disconnection)

Mammals use the new ventral circuits contained in the face/heart connection convey to others we are safe to approach. This separates our circuits from those of reptiles.

When we are challenged (frightened/upset) we mobilise or shut down and it turns off this ventral vagal connection.


How does Polyvagal Theory help us?

Facial expressions, eye movements and hearing are a portal that tell us the status of our physical and mental condition.

Porges offers us a different doorway to help ourselves find wellness – via finding safety in the body.

He offers to us that often the feeling of safety IS the core treatment.

Sometimes words are not enough to help us feel better.

When we don’t feel safe we cannot engage with life or any kind of therapy.

With the ventral vagal circuits turned on a window of tolerance is created so that we can find the solutions to emotional and physical wellbeing.