An exciting scientific advancement in the last nine years has been the development of something called Polyvagal theory. Dr. Stephen Porges published his book titled Polyvagal Theory: Neurophysiological Foundations of Emotions, Attachment, Communication, and Self-regulation in 2011.
Polyvagal theory explores the function of the vagus nerve. In this article for Yogapedia, I will give a little bit of information about the vagus nerve and how it is relevant when we consider the benefits of a yoga practice.
The Autonomic Nervous and Its Two Divisions
The vagus nerve is important to talk about when we are considering the benefits of yoga because it controls an important part of the nervous system, the autonomic nervous system.
You’ve probably heard it referenced when people talk about “fight or flight” mode. That’s the sympathetic nervous system.
The parasympathetic nervous system is sometimes referred to as the "rest and digest" system.
If you reference my article on Soothing Anxiety With Restorative Yoga you can read all about how to calm the nervous system through restorative yoga. This style of yoga activates the parasympathetic branch of the autonomic nervous system which vital for reducing anxiety as well as supporting overall health.
So What Is the Vagus Nerve all About?
The vagus nerve is the tenth cranial nerve. It starts in our brain stem and goes all the way down to our colon. On this nerve's path, it connects to the face, ears, neck, throat, and the body's major organs.
It permits the brain to receive information about what is happening in the body and it's said to control several of the body's functions including its involuntary functions. Our nervous system is consistently on lookout for potential stressors, which is also a main function of the vagus nerve.
Understanding how the vagus nerve functions gives us a lot of insight into how our emotions, attachments, communication, and self-regulation are directly linked to the physiological functions of the body.
Vagal tone refers to the nervous system's ability to switch between the parasympathetic and sympathetic nervous system accurately and effectively.
We are living in a society that gives us a tendency towards being stressed and in states that cause overactive sympathetic nervous systems. As humans, we are not used to living in cities, processing endless information through technology and other sources of stimuli.
Historically, we lived more in tune with nature and could rise to threats when needed. We would then return to a resting or parasympathetic state when the threat passed.
For example, we are misinterpreting an overflowing inbox of emails as a threat causing our sympathetic nervous system to activate. A healthy vagal tone allows us to better discern threats and supports the body's overall health, resilience, and recovery from stress.
Yoga As a Tool
According to many mental health researchers and professionals, including The Holistic Psychologist, Dr. Nicole LePera (founder of the Mindful Healing Center in Philadelphia, PA), yoga is a tool to develop a healthy vagal tone.
Other practices support vagal tone as well - some that may fall under other limbs of yoga besides asana. These include: singing, chanting, and breathing.
Although I often encourage passive practices (like restorative yoga) to activate the parasympathetic division of the autonomic nervous system, simply incorporating intentional breathing and ensuring time for a restful final savasana after an invigorating asana practice would help to support vagal tone as well.
You may activate the sympathetic branch of the autonomic nervous system during an invigorating practice, but allowing enough time for rest in the end is a great way to develop vagal tone because it allows your nervous system to learn how to relax after a perceived threat has retreated.
It enhances your resilience and ability to recover from stress.
The benefits of yoga in relation to the vagus nerve extend beyond just the automatic and involuntary responses of the organs that this nerve interacts with.
The vagus nerve also helps to facilitate the mind-body connection, which is what allows yoga to be such an effective tool for interoception. Interoception is our ability to sense what is going on within our body.
This sense is mediated by the vagus nerve as it is constantly collecting information from our body. It is believed that our "gut feelings" are an effect of the vagus nerve, as it runs through our digestive organs and is always on the lookout for potential threats.
Polyvagal Theory and The Three Gunas
One study looked at the parallels between the emotional, attachment based, communicative and self-regulative aspects of polyvagal theory - and how those compare to the physical, mental and social aspects of the three gunas.
It helps to bridge the gaps between the two worlds of emerging science and ancient yogic philosophy in order to develop the field of yoga therapy.
When we compare these neurobiological functions to the qualities of the three gunas, we can consider that:
- Sattva is calmness and purity - closely paralleled to the parasympathetic nervous system.
- Rajas is a state of movement and activity, much like the sympathetic nervous system.
- Tamas is the quality of self-restraint or inactivity and inertia. This can be compared the dorsal ventral complex in Polyvagal theory, which is the function of the vagus nerve that is responsible for a "freeze" response.
Like the gunas, each has its function, but too much in excess can create an unhealthy balance or an unhealthy vagal tone.
Dr. Stephen Porges' book and decades of research goes much further into Polyvagal theory that I have here, and I encourage you to go further into it if this interests you.
Take your time! The science can be very confusing at times.
Bridges East and West
The application of ancient yogic practices measured by science through modern developing theories is some of the most exciting research for mind-body healthcare professionals like myself and so many others.
Creating more evidence allows for yoga based therapies to become a more widely accepted and used evidence-based tool for healing and treatment of some of the most commonly diagnosed mental health disorders.
Understanding the function of the vagus nerve also creates space for a shift from a pathological or pharmacological view of "disorders."
We shift to simultaneously incorporating science while creating new evidence-based healing paths that encourage connection to the body rather than treating or masking "maladaptive" symptoms.
In an approach that embraces western science and ancient eastern healing practices, we are better able to honor and utilize the miraculousness and sacredness of the intricate and perfectly designed human body.