What Is… Polyvagal Theory

Diagram of polyvagal states safe, mobilized, and immobilized
Diagram of polyvagal theory by -luffyboy-, CC BY-SA 4.0 , via Wikimedia Commons

In this series, I dig a little deeper into the meaning of psychology-related terms. This week’s term is polyvagal theory.

Polyvagal theory was developed by Dr. Stephen Porges in 1994 to describe how the nervous system relates to the environment.

The vagus nerve

The name polyvagal theory comes from the multiple circuits that involve the vagus nerve, which is the tenth cranial nerve. Cranial nerves leave the brain directly rather than going through the spinal cord, and I remember having to memorize them in anatomy class in university. The vagus nerve gets around, and branches of it connect to the heart, lungs, and GI tract. It’s part of the parasympathetic nervous system, which is responsible for resting and digesting types of bodily functions.

Polyvagal theory

Polyvagal theory says that there are three circuits by which the vagus nerve communicates between distinct parts of the brain and the heart. These are influenced by environmental factors and are associated with different physiological and behavioural responses. Vagal withdrawal is linked to the mobilization of the fight or flight response, while safe environments promote increased vagal influence and spontaneous social engagement behaviours. The third circuit triggers shutdown mode when faced with danger.

The theory also says there’s a link between the vagal regulation of the heart and the muscles of the face. Heart rate variability fits into all of this somewhere, as does mammalian evolution.

The Stephen Porges show?

It appears to be somewhat of a one-man show; searching for polyvagal theory on Google Scholar doesn’t show much diversity in people building on Porges’ work, and in his papers that I looked at, he does a lot of referencing his own work. While it’s normal for a theory to have a founder, typically, other researchers will get involved in testing and applying the theory, so the lack of outside validation is somewhat concerning.

However, Porges does appear to have support from people who know what they’re talking about; his Polyvagal Institute advisors include Bessel van der Kolk (The Body Keeps the Score) and Gabor Maté (In the Realm of Hungry Ghosts). There’s been some criticism that the theory isn’t based in evidence, but I didn’t come across a source that articulated that well.

I may be totally mistaken in this impression, but Porges seems to be a fan of using a lot of words, particularly big words, without actually saying all that much. I found it difficult to get much meaningful substance out of his papers that I looked at.

Vagal tone

So, that was kinda sorta maybe what polyvagal theory is about, but what do you about it? If you Google “improve vagal tone,” various people will tell you that you can increase vagal tone by humming, deep breathing, putting your face in water to stimulate the diving reflex, or doing the Valsalva manoeuvre (as in straining to have a bowel movement). On a semi-related note, vagus nerve stimulation via an implanted device is approved for use in treatment-resistant depression.

Porges has also developed a Safe and Sound Protocol, which is a 5-hour auditory program delivered through headphones. His website claims that it helps with emotional control, behavioural organization, and hearing sensitivity and listening in various conditions, including autism.

I’d heard of polyvagal theory before in the context of the fight/flight/freeze response and window of tolerance and that kind of thing. I’ve got to say that looking it up didn’t leave me feeling any more enlightened. If you’re interested in getting more info from the horse’s mouth, you can watch this Youtube video by Dr. Porges.

Had you heard of polyvagal theory before? Does it make any more sense to you than it does to me?


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The Psychology Corner has an overview of terms covered in the What Is… series, along with a collection of scientifically validated psychological tests.

Ashley L. Peterson headshot

Ashley L. Peterson


Ashley is a former mental health nurse and pharmacist and the author of four books.

18 thoughts on “What Is… Polyvagal Theory”

  1. Good post. I’ve never heard of the theory before, but I have seen many books and articles about the Vagus Nerve. Sometimes when I search for books about depression on Amazon Kindle, there are like dozens of weird, self-published books about the Vagus Nerve. And many of them are very New Age-y type stuff, like “The Secret to Curing Depression.”

  2. I am a fan of polyvagal theory Ashley but agree it is very wordy and complex and I don’t fully understand it! For me the take home is in understanding the impact of trauma on our default reactivity – how easily triggered into fight/flight/freeze or flop and where we want to be is social engagement, playful etc. It helps explain why sometimes talking alone doesn’t help people overcome trauma – the body holds the score stuff and why how we breathe can really help our mental health and subjective state. Infection of the vagus nerve has been implicated in chronic fatigue syndrome recently which is interesting given that depression is a big part of CFS xx

    1. I’m glad you made more sense of it than I did! I think I agree with where he was going, but was a bit mystified as to his way of getting there.

  3. I took an online training on polyvagal theory and was left feeling it was more a theory base that did not offer much in the way of treatment modalities. Im glad to learn about the safe sound protocol you reference here. It sounds like an interesting resource. As always, thank you for your informative posts.

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