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The Vagus Nerve 101

“Vagus” is a Latin word that literally translates to “wandering.” The vagus nerve is a large nerve that wanders and surrounds many different organs in the body, thus its name. But don’t let its “wanderer” label lull you into thinking it doesn’t take its job seriously! “What happens in vagus stays in vagus” is not the case here. The vagus nerve is referred to as the “heart of the nervous system” because it’s the link between the body and the brain.


The vagus nerve (also called cranial nerve X) is two cranial nerves that is part of the parasympathetic nervous system. It has a left and right component. Both start at the medulla oblongata of the brain stem, which is the part of the brain that controls involuntary movements such as breathing, heartbeat, sneezing, and swallowing. From there, the vagus nerve heads down through the throat (larynx, esophagus), where it branches out to many of the organs of the viscera (heart, lungs, stomach, pancreas, spleen, liver, gallbladder, large and small intestines).


The two major functions of the vagus nerve play a critical role in maintaining overall wellbeing.

First, the vagus nerve is responsible for monitoring heart rate, peristalsis (contractions along the digestive tract that keep food moving), sweating, and several mouth movements, including speech, among others.

Second, it monitors what’s going on in the body and reports back to the brain. The brain interprets the information and sends signals back to respond to the information. About 80-90 percent of the vagus nerve fibers are solely dedicated to sending information to the brain on the state of the organs. If the brain receives information via the vagus nerve that something is out of the ordinary with one of the organs, the brain can send the appropriate signals to solve the problem and return the body to homeostasis (a relative state of equilibrium). If the vagus nerve is damaged or fails to function properly, crucial information about the health of the organs may not get to the brain. This means major issues for the functioning and health of the body as a whole.

Have you ever had a gut instinct or a visceral response to something? Recent studies suggest that the vagus nerve plays a major role in some of our emotional responses. The vagus nerve picks up on sensations or emotional intuitions in your gut and sends that information to the brain. For example, when you are nervous or excited, chemicals are released by the adrenal glands. The vagus nerve picks up on this change in the viscera and sends signals to the brain. The combination of the sensation in your gut and your brain processing that information direct your response to that nervous or excited state. Therefore, your reaction to a situation initiates from your gut rather than your brain. This is an interesting concept to consider. If your brain interprets the gut reaction, your response is determined by that interpretation. So, moral of the story: the gut is giving you the most pure reaction to a situation, while the brain is giving you a reasoned response.

Additionally, have you ever passed out from seeing blood? You’re not alone; that is also related to the vagus nerve. It is called a vasovagal response. If you see blood, it may cause emotional or physical stress. The physical stress may be relayed as pain, whereas the emotional stress may simply be related to the fear of what might happen because of the blood loss. Stress causes the sympathetic nervous system to turn on, causing a “fight or flight” response. In order to regain balance, the vagus nerve activates its vasovagal response to stimulate the parasympathetic nervous system. Unfortunately, in the case of a vasovagal response, the vagus nerve becomes overactivated to compensate for the sympathetic response, which in turn causes a dramatic drop in blood pressure and heart rate. The decreased blood flow leads to a lack of consciousness. A healthy nervous system is less likely to overdo this response, and vasovagal responses may become less frequent. In the meantime, don’t look while you’re getting your blood drawn!

How The Vagus Nerve Affects Me

If the vagus nerve is not working properly, the body’s ability to monitor and regulate the viscera and find balance between the sympathetic and parasympathetic nervous systems (the responses of fight and flight, and rest and digest) is compromised.

When the vagus nerve is unable to regulate the viscera, the body may experience a number of digestion-related issues. Because the vagus nerve is responsible for peristalsis, the muscle contractions that push food along the digestive tract, when the vagus nerve is damaged or not working properly, peristalsis is weakened and/or less frequent. Since the muscle contractions that push food along are not as strong, the food may become backed up as it travels along the digestive tract. This delayed gastric emptying (gastroparesis) causes abdominal pain after eating, nausea, loss of appetite, heartburn, and feeling full after eating very little, to name a few.

Further, an inability to balance the sympathetic and parasympathetic nervous responses of the autonomic nervous system can result in the body spending more time in the sympathetic nervous system. Living in this system means living in a constant state of fight or flight, otherwise know as living in a constant state of stress. This can lead to or exacerbate several conditions. Some conditions that arise from decreased vagus nerve activation and imbalance of the autonomic nervous system include GERD, various heart conditions, multiple sclerosis flareups, Alzheimer’s, migraines, epilepsy, depression, anxiety, and more.

Vagus Nerve Stimulation

Stimulating a weakened vagus nerve may help bring it back to optimal function. A new treatment called vagus nerve stimulation uses electrical impulses to activate the vagus nerve, thus stimulating a parasympathetic response in the body. It is currently being used to treat those who are not responding to traditional treatments for epilepsy and depression. Research suggests a link between overactivity of the sympathetic nervous system and temporal lobe epilepsy and depression. The rationale is, if stimulating the vagus nerve results in a parasympathetic response, then the autonomic nervous system can balance. This balance may decrease seizures and depressive moods/behaviors. The treatment is being studied for patients with other nervous system-related ailments, such as multiple sclerosis, Alzheimer’s and migraines.

How Breathing Can Help

Outside of medical vagus nerve stimulation, it is believed that the vagus nerve can be stimulated through controlled breathing. In yogic traditions, the Ujjayi breath (a breathing technique where you partially close your glottis in the throat to produce a sounded breath, sometimes likened to Darth Vader) is practiced specifically to stimulate the vagus nerve and trigger a parasympathetic response in the body. Other ways to stimulate the vagus nerve include diaphragmatic breathing (belly breathing), chanting, and various yoga asanas or shapes.

The great thing about breathing is that you do it all the time! The average person takes about 12 breaths per minute when at rest. That means that you easily take between 17,000 and 20,000 breaths per day. That’s a whole lot of opportunities to practice stimulating the vagus nerve!

My favorite breath technique is called “Back Breathing.” The ribs form a 360-degree cage around the lungs and the heart. They have the capacity to expand in all directions, side to side, front and back, up and down. Often, we don’t utilize our full range of motion in the ribs. By practicing expanding and contracting the ribs, we can increase our breath capacity and stimulate the vagus nerve.

Back Breathing

Start by placing one hand on either side of your ribcage. When you inhale, expand the ribs east/west (side to side) toward the hands. When you exhale, contract the front of the rib cage. Now, move your hands toward the back of your ribs, or if that’s not possible, stand or sit with your back against a wall. Now inhale and expand into the back of the ribs. Try to keep your shoulders out of the equation (don’t let them rise and fall as you breathe). This one may be more challenging! Again, exhale and contract the front of the ribs together. If possible, let each inhale take up the same amount of time as each exhale. But don’t sweat it! Remember, this is designed to help calm your nervous system.

Challenge yourself to practice expanding and contracting the ribs for 3-5 breath cycles at least three times throughout your day, whether it be when you first wake up, during your commute to work, sitting at your desk, or just before you fall asleep at night. Let us know how it makes you feel!

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