Polyvagal Theory: how our nervous system really works

I have just finished The Pocket Guide to the Polyvagal Theory by Dr Stephen Porges. I found it a really tough, technical read. That said, I persevered because I found its messages to be incredibly important. This book has profoundly changed the way I understand my nervous system (admittedly off a very low base!!).

My previous understanding of my nervous system:

  1. I need to spend less time in my sympathetic nervous system (fight or flight) and more time in my parasympathetic nervous system (rest and digest)
  2. Sometimes my body has weird, very physical reactions to things in a way unrelated to how my conscious mind reacts (vertigo, claustrophobia, fainting when I chopped the skin off the top of my finger)

Polyvagal Theory:

There are 3 parts to our autonomic nervous system and we can think of them as a hierarchy

  1. Parasympathetic nervous system. Newest mammalian system. Allows us to socialize with fellow humans from a place of safety. Controlled by the vagus nerve
  2. Sympathetic nervous system. Older mammalian system. Allows us to mobilize in a stress / fear scenario. Very useful! But not healthy if we find ourselves chronically in this state because our body cannot thrive when in a protected state
  3. Shutdown / immobilization. Ancient, reptilian system, also controlled by the vagus nerve. Protects our body in a ‘fear of death or extreme pain’ scenario. This is the least understood of the systems and explains reactions like vertigo / fainting. Many animals can play dead when in fear of death, by slowing their heart-rate right down. The problem for humans is that because of our need for oxygenated blood, this can trigger unconsciousness!

The theory’s main conclusion is that to thrive in life, our nervous system needs to feel safe.


On a general level, it’s really useful for us all to know why and how our immobilization response works.

I have noticed my vertigo getting worse in recent years and have been frustrated because I cannot ‘control’ it or talk myself out of it. Dr Porges makes the really important point that this is a decision the body makes for us. Eg: He was very excited to be undergoing an MRI because he and his colleagues were sure to see some very helpful findings from it for their research. Once he went into the machine however, he had a full-on panic attack. He calls this neuroception – it’s our nervous system’s perception of threat, not our conscious mind’s logical analysis of threat. We can’t help it!!! Moreover – it can save our lives. He says: “feeling safe is dependent on unique cues in the environment and in our relationships that have an active inhibition on defense circuits and promote health and feelings of love and trust.”

For any sufferers of trauma, especially rape / assault / imprisonment etc, it may UNLOCK the key to their behaviour at the time and after the event.

Dr Porges explains that many trauma / attack victims report feelings of disassociation and often memory loss during their traumatic event. Afterwards they feel guilty for having been ‘passive’ and blame themselves for not having fought back harder against their attacker. Therapists using Dr Porges’ theory have explained to their patients that this ‘immobilization’ may have saved their lives, in the same way that a mouse can in fact avoid death by feigning death in the jaws of a cat. Sometimes just the knowledge that their body did a wonderful, possibly live-saving thing for them and did not ‘let them down’ can enable trauma victims to start to move on. (It also provides an explanation for why trauma suffers are unable to move on as this state can be very difficult to unlock).

Polyvagal Theory has seriously interesting potential consequences for AUTISM:

Dr Porges has done a lot of work with autistic children and in particular, those with auditory problems. His theory is as follows:

  • People with autism find it harder to regulate their state in part because their nervous system is receiving many more signs of danger than other people
  • Many of these danger signals are auditory. As a species we are engineered to respond well to prosody (melodic sounds like a mother’s voice, lullabies, folk music) – this gives us the necessary safety cues.
  • However, we perceive lower frequency sounds as more predatory, and people with autism can be far more sensitive to these sounds on an unconscious level. Ironically, institutions like schools and hospitals, which should be perceived as safe, are often full of danger cues. Hospitals are the worst offender with noisy machines (MRI anyone?), strip-lighting and invasive behaviour.
  • Dr Porges has done a great deal of work with autistic children, providing listening therapy which features highly melodic music to feed the patient safety cues. He notes that many of the so-called auditory ‘problems’ which people with autism face result from a higher awareness of predatory sounds (any low-frequency background noise) which prevents them from tuning into the human voice within this melange. He has had great success in rebalancing nervous systems to turn off defensive strategies.
  • He feels strongly that many places of learning for people with autism do not sufficiently understand the importance of safety cues and are not set up to make their students’ nervous systems feel safe. Many of these places can focus on autism as a ‘learning difficulty’ when in fact it’s a difficulty in regulating one’s state: “Basically, I am questioning the goals of our institutions. Are the goals of our institutions to educate people with more information, or are our goals to make people better able to reciprocally interact and to regulate each other to feel good?”


The vagus is a huge nerve with 2 main branches, starting in the brain stem and finishing in the abdomen where it branches out.

The reason it’s so critical is that it sends two-way feedback to and from the brain to both the visceral organs, and to the muscles regulating the face and head (so it’s both a motor nerve and sensory nerve)

Therefore, the vagus nerve regulates so much of our bodies and our nervous systems and is critical to our ability to flourish, grow and create. For example, the neural pathway for healing overlaps with the vagal pathway for social engagement – if humans are isolated, we will not thrive (as an aside, often human and cellular behaviours mirror each other – cancer takes root as a result of cells being isolated)

We know that having a strong vagal tone is critical for being in a state conducive to health and wellbeing, and a strong vagal tone allows us to access our parasympathetic nervous system much more quickly and easily after stress. Ways to strengthen our vagal tone include:

  • Exercises that increase the length of our exhalations – talking, singing, wind instruments, yogic breathing (pranayama), 2x breathing (exhalation is 2x the length of the inhalation), humming and chanting
  • Heart Rate Variability (HRV) training, which is a way to both measure and improve your vagal tone (high HRV is correlated with good vagal tone). There will be another post on HRV soon
  • Cold exposure – finish your shower on cold or stick your face in a cold basin of water
  • Meditation
  • Dietary supplements: Omega 3 and probiotics
  • Socialising
  • Laughing

To finish, some quotes from Dr Porges’ book that I thought were meaningful (bolding is mine):

“This ability to feel another’s feelings is based on our neurophysiology. We can detect and interpret how another person feels, because the nerves that control the striated muscles of the face and head are linked in the brainstem to the myelinated smart vagus. We functionally wear our heart on our face.”

“The ability to regulate state, when context and demands dynamically change, is frequently used to operationalize resilience.” [I like this. If we take what resilience looks like physiologically, it’s our ability to move between states effectively]

To me, when we use the word “stress,” what we’re really talking about is mobilization—and mobilization isn’t always bad. Mobilization is part of being a mammal, part of being a human. So the issue is when mobilization doesn’t have a functional outcome; then maybe that could be called “maladaptive mobilization,” and maybe that’s what “stress” is.

“An interest in our own bodily feelings has been neglected and often disrespected in our contemporary society. Often we have been taught, as part of a strategy to manage our behavior, to reject the feedback that our body is telling us.

when our body goes into certain states related to being traumatized, it is acting heroically. The body is helping us, it is saving us, and our body is not failing us—it’s attempting to help us survive.”

those who are bold and seek novelty may also be those who have or who have had the most efficient pathways back to safety. It’s not that we seek novelty just for the sake of “seeking novelty.” In life, the people who are bold thinkers are willing to take gambles. They’re not insecure in novel situations. They’re also people who have strong social support networks”

“We live in a medically oriented world that treats organs as if each organ can be treated independently and is not part of an integrative and interactive autonomic nervous system.”

On coaching a colleague with stage-fright right before she got on stage, by using speech as a way to drive longer exhalations and stimulate her vagus nerve:

“I said to her, “Extend the duration of your phrases. Add more words to your phrases before you take a breath.” Initially, she couldn’t do it; she couldn’t get another word in. Finally, she got another word in, and then she got another, and then she was able to use a single breath for longer phrases. She started talking in a more engaging way. She then gave a wonderful and engaging introduction.”

You can learn more about Dr Porges’ work on his website.

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