The Vagus Nerve

Lesson Overview

In this lesson, we introduce the vagus nerve and describe practices that raise vagal tone.

Objective

Become familiar with the significance of vagal tone in the experience of stress and the effectiveness of yoga techniques.

Description

Describe the vagus nerve and its location. Explain what is meant by the term, “vagal tone” and what is associated with high vagal tone and low vagal tone. Explain vagus nerve stimulation (VNS) and describe practices that raise vagal tone, boost the immune system, reduce inflammation and contribute to feelings of contentment.

Form

  • An element of the parasympathetic nervous system, the vagus nerve is one of 12 pairs of cranial nerves that originate in the brain.
  • It is the largest and most complex nerve in the body.
  • From the brain, it passes through the neck, spreading nerve fibers through the body.
  • “Vagus” means “wandering” in Latin and the vagus nerve is also known as the “wandering nerve” because from its two origination points in the brain, it branches out to the “lowest viscera of the abdomen, touching your heart and most major organs along the way.” (Christopher Bergland)

Function

  • The vagus nerve has been called the “air traffic controller” because it helps, among other things, to regulate major bodily functions, influencing the lungs, heart, stomach and intestines.
  • The vagus nerve both sends and receives signals between the brain and visceral organs.
  • It sends sensory information about the state of the body’s organs to the brain. And, in a mind-body feedback loop, messages also travel to the organs, signaling if there is an inner-calm or if there is danger.  (Christopher Bergland)
  • In the case of chronic stress, “the SNS becomes consistently dominant and the vagal brake is less frequently applied.” (B. Grace Bullock)

In the YogaUOnline article The Vagus Nerve, Olga Kabel describes all of these functions for the vagus nerve:

  1. Involved in managing the Autonomic Nervous System
  2. Communicates between gut and brain
  3. Regulates muscle movement for breathing
  4. Helps to decrease inflammation
  5. Impacts heart rate and blood pressure
  6. Helps improve mood
  7. Essential in fear management
  8. Impacts learning and memory
  9. Can help relieve cluster headaches

Information / “Gut Instincts” from Organs to Brain

The vagus nerve is constantly sending updated sensory information about the state of the body’s organs “upstream” to your brain via afferent nerves. In fact, 80-90% of the nerve fibers in the vagus nerve are dedicated to communicating the state of your viscera up to your brain… Visceral feelings and gut instincts are literally emotional intuitions transferred up to your brain via the vagus nerve. In previous studies, signals from the vagus nerve traveling from the gut to the brain have been linked to modulating mood and distinctive types of fear and anxiety. – Christopher Bergland

Linked to Emotion, Cognition and Behavior

It is inherently linked to social behavior through its activation of the muscles of the face and neck including those that influence facial expression and vocal resonance. Higher states of vagal tone and the capacity to effectively use the vagal brake are linked to greater emotional stability, cognitive flexibility, behavioral regulation, prosody of speech, and appropriate facial expression – all key capacities of socially skilled behavior. Conversely, poor vagal brake regulation is linked to dysfunctional behavior. – B Grace Bullock PhD

Research Shows Mind-Body Communication/Connection

In 2011, [researchers]… conducted a breakthrough experiment where they stimulated the vagus nerve in rheumatoid arthritis patients by implanting an electronic device, similar to a pacemaker. Patients on the trial showed significant improvement and around one-third are in remission – off medication and effectively cured. Measures of inflammation in their blood also went down, and even those who had not experienced clinically significant improvements insisted it helped them; nobody wanted it removed… [Researchers reported that] vagal nerve stimulation appears to restore the body’s natural balance. It reduces the over-production of inflammatory proteins that cause chronic inflammation but does not affect healthy immune function… [As a result of this research,] the Western medical world’s understanding of how the body manages disease has changed forever. Tak says, “It’s become increasingly clear that we can’t see organ systems in isolation, like we did in the past. It’s very clear that the human is one entity: mind and body are one… We didn’t have the science to agree with what may seem intuitive. Now we have new data and new insights.” At last, science is catching up with what yogis and other mystic and healing traditions around the world have known for thousands of years. – Edwina Shaw

About Vagal Tone

Vagal Tone

“Healthy vagus nerve communication between your gut and your brain helps to slow you down like the brakes on your car.” (Christopher Bergland) “Vagal tone is a general term for the responsiveness of our braking system.” (Craig Marker)

High Vagal Tone

  • High vagal tone is linked to physical and psychological well-being.
  • It relates to self-regulation: the ability to move from more active and stressful states to more relaxed ones “without getting unduly perturbed.”
  • High vagal tone is associated with better health, resilience, and sustained attention.

Associated with Compassion

People with high vagal tone have higher levels of oxytocin and are more prone to feelings of altruism. So the vagus has also been called the love nerve, or the compassion nerve. According to researcher Dr Dacher Keltner, it is vagus activation that gives us the warm, expansive feeling in our chests when we experience — or even think about — human kindness. We used to think that some people were just born with high vagal tone. We now know that vagal tone can be improved. – Dr. Lara Briden

The Self-Sustaining Upward Spiral

[Researchers…] discovered that a high vagal tone index was part of a feedback loop between positive emotions, physical health, and positive social connections. Their research suggests that positive emotions, robust social connections, and physical health influence one another in a self-sustaining upward spiral dynamic and feedback loop that scientists are just beginning to understand. – Christopher Bergland

Low Vagal Tone

  • Low vagal tone is linked with inflammation, negative moods, loneliness, heart attacks and stroke. (Christopher Bergland)
  • It is associated with a “sense of depletion,” digestion issues, depressionpost-traumatic stress disorder, chronic pain and epilepsy. (Angela Wilson)

Conditions Significantly Impacted by Yoga

Not surprisingly, low vagal tone is correlated with such health conditions as depression, post-traumatic stress disorder, chronic pain, and epilepsy—not coincidentally, the same conditions that show significant improvement with yoga practice. – Angela Wilson

Yogic Practices to Affect Vagal Tone

Introduction

  • While there are implanted medical devices for vagus nerve stimulation (VNS), Olga Kabel explains that we “cannot directly and consciously stimulate [the] vagus nerve like you would with an electrical device.” Rather, the vagus nerve is stimulated indirectly by activities that induce the Relaxation Response.
  • Kabel goes on to explain that because the vagus nerve passes through the throat and lungs, that breathing, and chanting are sensible approaches to induce the Relaxation Response and a related stimulation of the vagus nerve.
  • And in fact, research (see below) has shown that lovingkindness meditation, chanting and pranayama positively affect the vagus nerve.
  • Dr. Ram Rao notes that yoga practices sustain vagal tone, encouraging a healthy shift from the Fight or Flight Response to the Relaxation Response.

Vagal Toning Techniques

In this excellent article, the author observes how we activate the vagus nerve by stimulating the vocal cords through such instinctive actions as groaning when in pain and moaning during childbirth. The author goes on to advise that regular practice of the following techniques “will raise your vagal tone, boosting your immune system, reducing any inflammation and contributing to feelings of well-being and contentment.”

  1. Brahmari Pranayama
  2. Ujjayi Pranayama
  3. Nadi Shodhana Pranayama
  4. Chanting
  5. Singing
  6. Talking
  7. Lovingkindness Meditation
  8. Washing your face with icy water

Research & Readings

In Scientific Research: How Yoga Works, Angela Wilson highlighted these study results:

  • Results from a study conducted by the Boston University School of Medicine led researchers to hypothesize that yoga works to increase the body’s ability to successfully respond to stress by increasing vagal tone and thereby regulating the nervous system.
  • Ujjayi Pranayama was shown to increase the relaxation response and heart rate variability (a function of stress resilience).
  • Chanting Om out loud increased vagal tone and the relaxation response more than chanting it silently.

More Research Results

In 2010… psychologists… conducted an experiment to see if the relationship between vagal tone and well-being could be harnessed without the need for implants… Half of the participants were taught a meditation technique to promote feelings of goodwill towards themselves and others. Those who meditated showed a significant rise in vagal tone, which was associated with reported increases in positive emotions… “That was the first experimental evidence that if you increased positive emotions and that led to increased social closeness, then vagal tone changed.” Similarly, in 2010… researchers… demonstrated the immediate beneficial effect of… Bhramari pranayama on blood pressure and heart rate, both linked to the functioning of the vagus nerve. The study proved that… even when done for only five minutes, [it] stimulated the vagus nerve, activating the parasympathetic system which calmed the heart rate and lowered blood pressure. – Edwina Shaw

Breathing and Sounding

You can indirectly stimulate your vagus nerve by getting yourself into the rest-and-digest mode because this nerve gets activated during the parasympathetic response. How do we do that? Remember which parts of your body the vagus nerve branches out to? It goes to your throat, lungs, heart and abdominal organs… You cannot consciously control your heart, your kidneys or your small intestine, but you can control the depth of your breathing (to a certain degree) and the muscles of your larynx (that open and close the vocal cords and control the pitch of sound), which the branches of the vagus nerve also happen to innervate. So then it would make sense that to facilitate the parasympathetic response in the body (and stimulate the vagus nerve), we would need to exert influence over those two main areas. – Olga Kabel

Yoga Asanas Coupled with Breath Stimulate Activity

Better prognosis of the health status can be predicted by the strength of the vagal tone especially in people who are recovering from chronic diseases. However, vagal tone is not static; it keeps fluctuating based on our activities, lifestyle, and moods. We all need to strive to increase the activity of the vagal nerve to optimal levels and sustain that optimal tone… Since the vagus nerve innervates the chest, any kind of practices or activities that influence the energy flow through the vagus nerve will have a profound effect on the respiration and circulation. Yoga asanas coupled with the breath stimulate electrical and mechanical activities in the body. The electric activity is reflected in the vagus nerve stimulus that initiates in the brain and travels deep down to the organs for mechanical actions to be initiated… Furthermore, yoga practices sustain the vagal tone and encourage a shift from Fight or Flight Response to Relaxation mode. – Dr. Ram Rao