How many times have you heard the expression, “What’s eating you?” or asked yourself whether you’d be able to “stomach” the sight of something horrific? When you’re anxious do you feel nauseous, experience butterflies in your stomach, or have a sudden urge to evacuate the remainder of your lunch? These digestive metaphors remind us that so much of what and how we feel doesn’t come from our logical brain; it comes directly from our gut. Turns out there’s a reason for that: Our gut, which begins in the esophagus and extends all the way to the anus, is lined with millions of neurons, which make up, quite literally, a second brain. Called the enteric (or intestinal) brain, it communicates with our bigger, upstairs brain, relaying those “gut” feelings and providing clues to our mental and emotional states, according to Columbia University neurogastroenterologist Michael Gershon, MD, author of The Second Brain. It does that through the vagus nerve, the longest cranial nerve in the body, which is considered mission control for the parasympathetic (rest-and-digest) nervous system. The ancients might say that the vijnanamaya kosha (our intuitive, wisdom mind) is the vagus nerve of the subtle body.
The vagus nerve roams throughout the body, communicating with every internal organ, searching for signs of imbalance. But its connection to the enteric brain is what helps us receive and digest our emotions without too much interference from our logical mind. Yoga teaches us that by accessing the wisdom mind, we can learn to listen deeply and bear witness to what’s going on inside. When vagus nerve activity increases (researchers call that high vagal tone), the nervous system comes into balance more readily, allowing us to meet the challenges in our day-to-day with more ease and to return to calm a lot quicker.
On the other hand, persistent anxiety, unrelenting stress, depression, unprocessed emotions, and PTSD, as well as poor digestion, chronic fatigue, and inflammatory diseases are all signs that the nervous system is stuck on a fight-flight-freeze, deer-in-the-headlights response and the vagus nerve activity decreases. The good news? Yoga for anxiety and other mind-body practices can increase vagal tone, thereby dampening that frantic response of the sympathetic nervous system and reestablishing connection with the rest-and-digest response of the parasympathetic.There’s so much more to learn about the vagus nerve than what we’ve discussed here, of course. If you’re interested, I recommend Stephen Porges’s book, The Pocket Guide to the Polyvagal Theory: The Transformative Power of Feeling Safe or Dr. Arielle Schwartz’s articles online.