Why Is the Vagus Nerve Important To Your Health?

by Last updated Jan 18, 2023 | Published on Jan 18, 2023

Why is the Vagus Nerve function so crucial for your health? I’m going to answer that question in this article.

Are you or someone you know suffering from conditions like anxiety, depression, PTSD, autoimmune disease, and chronic pain issues like fibromyalgia? If so, understanding the Vagus Nerve can be a game changer. First, let’s start with the basics: where does the word vagus come from? It’s from the Latin “vagal,” which means wandering and is also the root of words like vagrant or vagabond.

vagabond artwork

Vagrant or Vagabond

And just so there’s no confusion. I want to make sure you know which Vagus we’re talking about. We’re not talking about the Las Vegas nerve, which is associated with wild partying behavior, and a desire for no one to know what you did after the fact. That subject would be for a different article.

vegas party

The Las Vegas Nerve

The following image shows the Vagus Nerve in yellow. You can see that two branches of the Vagus Nerve come down the front of the throat from the brainstem, into the chest cavity, and to the abdominal cavity. There are also facial nerves that are yellow as well.

diagram showing the vagus nerve

The Vagus Nerve is colored yellow

What does the Vagus Nerve do?

The Vagus Nerve function is to adjust your physiology so you can adapt to your environment successfully. Adapting successfully includes adjusting the heart and lung rate, hormone levels, blood flow, digestion, etc. For example, imagine the difference in your physiology when you run for your life from a tiger compared to going to sleep at night when you’re safe. Your physiology would be quite different in these two scenarios.

Essentially, the Vagus Nerve connects the brain in your internal organs to your heart and lungs and to the brain in your head. The messages sent through the Vagus Nerve are what we call vagal tone, like a musical tone. The tone changes depending on the challenges or opportunities you face from moment to moment. Therefore, the Vagus Nerve acts as an information superhighway that connects our three brains. Ultimately, the tone sent through the Vagus Nerve determines how you respond to your environmental sights, sounds, people, and the news story you just watched on your smartphone.

We have three brains that influence our behavior

What are the three brains? I’ll explain what they are before the end of this article, and we’re going to start with two of them right now. The first brain is the Old Vagus, or the ancient brain, located in your gut.

The Old Vagus is associated with what I call shutdown energy. The right branch of the vagus nerve is linked with the Old Vagus. The right vagal branch wanders from the right side of the neck into the heart and lungs, then through the gut/internal organs.

Old vagus shutdown brain diagram

The right branch of the vagus nerve

Then we have what’s referred to as the New Vagus, or the Civilized Brain. The New Vagus starts from the brainstem/left side of the neck and wraps around the heart and lungs. In his research, Dr. Porge’s discovered that the left branch of the Vagus Nerve connects to the nerves and other structures associated with head-turning and facial muscles. The facial muscles control the eyes, ears, mouth, and all the organs used for singing, talking, eating, and hearing. Dr. Porges calls this combination of structures the Social Engagement System.

new vagus -  civilized/calm down brain

The left branch of the vagus nerve

The Social Engagement System and the left branch of the Vagus are associated with calm, centered, safe places in our nervous system. The New Vagus is the key to understanding how the Social Engagement System either shuts off or turns on. Consequently, when this New Vagus becomes dysfunctional, we get stuck in chronic conditions like chronic pain, autoimmune disease, and depression.

Now we’re going to go into more detail about the three different brains. In the next illustration, I’ve color-coded the nerves associated with each of those brains. Red is the Old Vagus, yellow on the spine area is the Sympathetic Nervous System/Action Brain, and the New Vagus is green.

color coded nerve diagram

Color coded nerve chart

Our body controls our thoughts, feelings, and behaviors most of the time, not our conscious mind.

The traditional scientific view of the Vagus Nerve suggests that most of the control over our decisions is from the brain to the body. For many years scientists have believed that the brain controls the body. But Dr. Porges’s research and many other scientists have discovered that most control comes from the internal organs (from the gut to the cranial brain). Most of the time, the gut-brain controls our thoughts, feelings, and behavior. It decides for us how we respond to our world.

This concept might be hard to grasp for many readers because it contradicts what we have been told for many years. However, current neuroscience says that most of your decisions are made unconsciously by your body.

The gut-brain tells the cranial brain what to do most of the time. Typically, 80% of the influence goes from the gut to the cranial brain. Alternatively, 20% of the influence goes from the cranial brain to the gut. This means that we have some conscious control over our physiology, but not nearly as much as we thought.

How our three brains developed through evolution

Let’s start with our Old Vagus, developed when we were reptiles hundreds of millions of years ago. The primary survival strategy of the Old Vagus in the face of overwhelming threat is to play dead, which is why I call it the Shutdown Brain. Remember that this ancient system controls most of our emotional responses to the world.

color coded nerve diagram

The Old Vagus developed when we were reptiles

Then hundreds of millions of years later, the Sympathetic Nervous System developed as we evolved into tree-dwelling primates. The Sympathetic Nervous System helps us survive by allowing for aggressive and defensive actions in response to threats which is why I call it the Action Brain. And as you can see in the photo, this primate is assertive, showing teeth, possibly in response to another mammal.

primate in the jungle

We developed the Sympathetic Nervous System (Action Brain) as primates

With the addition of the Sympathetic Nervous System allowing us to fight & flight, we had more options for survival. When facing challenges, we could fight off threats or run away from them. If we ran away and the danger caught up with us, we could still play dead by activating the Old Vagus (Shut Down Brain).

Then hundreds of millions of years later, we developed into humans, which included the addition of a new part of our nervous system the New Vagus (Calm Down Brain) responsible for civilized behavior. Essentially the primates that cooperated socially more effectively were the ones that survived and reproduced more often. A special wiring developed from this highly cooperative behavior, including deep learning, deep spiritual states, play, social cooperation, and many other positive aspects of being a safe, healthy human.

mother co-regulating with her baby

The New Vagus facilitates safe social bonding

Our brain in the gut must feel safe for us to thrive

For civilized behavior to work, we must experience feelings of safety, especially a safe connection with other people. Activating civilized behavior requires taming the more primitive responses of fight & flight and shutdown, which is why I call The New Vagus: the Calm Down/Civilized Brain. Consequently, if we’re not socially successful, meaning that we are not desirable to connect with, we lose access to other people. We need social safety to turn on the New Vagus, without it we lose access to traits like curiosity, play and deep rest for healing.

Dr. Porges explains that when the New Vagus (or the part of the New Vagus called the Social Engagement System) is activated, it allows us to tame and utilize the ancient brains. Those ancient brains are oriented toward behaviors designed to handle dangerous and life-threatening situations. However, when the Social Engagement System is turned on, the primitive behavior gets transformed into behavior that supports social bonding, healing, creativity, higher brain states, etc.

Therefore, when we are in our New Vagus: 

1. The Sympathetic Nervous System (the Action Brain – which is usually used for fear-based responses) becomes used for play, exploration, deep learning, and cooperative work. When the New Vagus (Calm Down Brain) is dominant, it allows you to be close and vulnerable with other people without getting aggressive and defensive and hurting each other.

2. The Old Vegas (Shutdown Brain) gets recruited; instead of shutting down and playing dead, it transforms into feelings of calm, safety, feeling grounded, and stillness. When the New Vagus (Calm Down Brain) is dominant, it allows us to access deep spiritual states, including a connection to the Divine.

Do we develop chronic conditions if the New Vagus can’t turn on?

Now we’ll look at how you can help the New Vagus be more dominant. When the New Vagus is on more often, you can effectively digest the world around you, allowing you to thrive.

If there is no access to the New Vagus/Calm Down Brain, the only responses available to you would be aggressive/defensive (Sympathetic Nervous System/Action Brain) or collapsed/depressed (Old Vagus/Shutdown Brain). Therefore, if you are stuck in a nervous system dynamic that only allows for attack, defense, and playing dead, and this pattern goes on for weeks, months, or years your body wears out. Your body is designed to be in these two survival states only occasionally (in emergencies); otherwise, it wears out, the immune system goes into overdrive, you become more susceptible to disease, and age faster.

You need to have the New Vegas active to repair and heal.

How can I access the New Vagus/Calm Down Brain more often?

This magnified image from the colored coded nerve chart (earlier in this article) shows you the heart and the nerves associated with the three different brains. You can see all three of them are connected to the heart.

heart nerves

Close up of the heart nerves

The heart, lungs, and facial nerves are vital for switching ON or OFF different states/survival strategies. Therefore, the key to turning on the New Vagus and keeping it on is to engage in reciprocal interactions with other people and through personal practices that exercise the nerves of the heart, lungs, and face. Exercising the components of the Social Engagement System (The Calm Down Brain) regularly, makes it more dominate more often. These exercises must engage the facial muscles, including hearing, eyesight, voice, and breath.

social engagement system nerves

Social engagement system nerves (green)

If we’re talking, singing, or playing games with others, we use breath, voice, and face to stay connected. If you’re practicing breath work like pranayama, you’re exercising your face, heart, and lungs. Pranayama and other breath practices are effective because they vary how you use your face and breath challenging your subconscious nervous system to change your vagal tone to adapt. Therefore, personal practice and highly reciprocal social interactions stimulate your New Vagus and make it easier for it to turn on and stay on.

Now that you’ve learned some current neuroscience, you may ask: “How do I apply this knowledge in my life?” I created a guide for you as a tool for applying these new scientific principles in your life. I call it The Polyvagal Practice Self-Awareness Guide.

polyvagal practice self-awareness guide


You can see in the graphic of The Self-Awareness Guide that the colors coincide with the science I just covered. Red is the ancient Old Vagus/Shutdown Brain. The Sympathetic Nervous System/Action Brain is yellow, and the New Vagus/Calm Down Brain is green. I’m working on articles, videos and a course that explains in more detail how to use this chart, so stay tuned for more knowledge and tips.

The Polyvagal Practice Self-Awareness Guide aims to help you identify which of the survival states you’re in at any given moment. When you recognize which of your three brains is dominant, you can better determine whether your response to a person or situation is functional and whether it makes your life better or worse. And then, you may be motivated to do practices that help shift your subconscious reaction to a specific event, person, or situation. 

For examples of practices that support the activation of the New Vagus for greater stress resilience and health check out these videos and articles:

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