The vagus nerve has been getting a lot of attention for its ability to combat anxiety, prevent seizures and long COVID, reduce inflammation, prevent digestive problems such as irritable bowel syndrome, and put the body into a healing state. But what is the vagus nerve? This “wandering” nerve extends from the brain through the neck and chest into the colon, controlling the “rest and digest” side of the nervous system that calms the body back down after a “fight or flight” stress reaction. Chronic stress from an infection, an inflammatory condition (such as an autoimmune disease), or a difficult time in life can lead to its dysfunction.

There's a lot of new research investigating how vagus nerve stimulation can be used to reduce the severity of autoimmune diseases by shutting off pro-inflammatory cytokine production and ending haywire immune responses. A recent study of individuals with rheumatoid arthritis (RA) showed promising results, with participants having clinically significant improvements in their RA symptoms and inflammatory cytokine levels after a few weeks of vagus nerve stimulation. (Source)

This article digs deep into the science of what the vagus nerve does, how it can be dysregulated by stressors, and stimulation techniques you can use that may activate it to support your health.

The Vagus Nerve: What It Is & What It Does

The vagus nerve is the master nerve of the parasympathetic nervous system. It extends from the brain to the large intestine, branching into the throat, lungs, heart, and digestive system. This nerve controls essential, involuntary functions — the thousands of movements, secretions, and contractions occurring in your body without your conscious control. Some of its most important jobs are to help you swallow, move food through your intestines, make glands secrete substances such as bile and insulin, mediate immune responses to entering pathogens, and regulate heart rate. (Source)

At the root of the vagus nerve's healing powers is its control over the gut–brain axis. On this axis, the brain is constantly sending your gut information about your environment, safety, and emotional state, while your gut is sending back to the brain information about your microbiome, inflammation levels, and diet. The gut is a sensory organ similar to the eyes — it’s responsible for telling your brain what is going on. But unlike the eyes, which communicate information about the external world, the gut tells the brain about your internal world. (Source)

It's the job of the vagus nerve to transmit these important signals back and forth between the brain and body. The vagus nerve is covered in receptors for molecules such as nutrients, glucose, peptides, hormones, and chemicals. These molecules trigger the vagus nerve to conduct a specific neural signal. (Source)

For example, if you eat a bagel, the glucose molecules bind to vagus nerve receptors in your stomach, which triggers the vagus nerve to slow stomach emptying so your blood sugar doesn’t spike too high. It also tells the brain when you are full. (Source)

The vagus nerve also has receptors for cytokines, signaling molecules made by our immune cells to alert the body to danger and stimulate an inflammatory response. The vagus nerve can change cytokine levels depending on the needs of your body, reducing the inflammation that is often elevated in people with autoimmune disease. (Source)

Before jumping into what causes vagus nerve dysfunction and how you can fix it, let’s do a quick recap on your autonomic nervous system.

The Lowdown on the Autonomic Nervous System

The autonomic nervous system is responsible for almost all of the body’s involuntary functions. Within this system are three parts.

• First is the sympathetic nervous system, which controls fight or flight functions. This includes increasing heart rate, constricting veins to raise blood pressure, and moving blood into the muscles and lungs for physical activity.
• Next is the parasympathetic nervous system, mainly controlled by the vagus nerve, which does the opposite. It lowers blood pressure, calms heart rate, moves blood from the extremities into the gastrointestinal tract, and increases bowel motility.
• The third part of this system is called the enteric nervous system. This is a web of nerves throughout the gastrointestinal tract, often called the second brain of the body. Both the sympathetic and parasympathetic nervous systems interact with the enteric nervous system, impacting immunity, mood, hunger, and inflammation.

Your body switches between sympathetic and parasympathetic modes throughout the day, depending on the situation. Whereas while reading a novel you will hopefully be in parasympathetic mode, giving a work presentation might activate your sympathetic nervous system. This is how environmental circumstances, especially stress, change vagus nerve activity. (Source)

What Causes Problems With the Vagus Nerve

Vagus nerve activity varies from person to person, which is why some people can bounce back from stressful events faster than others. There are two main ways that vagus nerve dysregulation occurs. The first is when the nerve is constantly being shut off from stress, and the second is when an inflammatory condition either damages or alters its function.

Chronic stress, anxiety, trauma, or post-traumatic stress disorder all convey danger to the brain, activating the sympathetic nervous system’s fight or flight mode. When your body is constantly receiving information that it’s unsafe, it slows digestion and healing to focus on survival. This deactivates the vagus nerve, leading to symptoms such as indigestion, constipation, poor immunity, and low mood. (Source, Source, Source)

A handful of illnesses such as gastroparesis, in which stomach muscles malfunction and keep the stomach from emptying properly, and vasovagal syncope, in which various triggers cause reflexive fainting, have been noted to damage the vagus nerve. Autoimmune conditions such as lupus and multiple sclerosis, which occur when the immune system attacks healthy tissue and nerves, can also cause damage. (Source, Source)

Surprisingly, illnesses such as chronic fatigue syndrome, chronic inflammatory response syndrome, depression, myalgia, and long COVID may be connected to vagus nerve dysfunction. When immune cells face a pathogen, they produce cytokines. The vagus nerve is covered in receptors for many of these cytokines, so it can signal the brain and body that there is an infection.

In response, the brain initiates “sickness behavior” — a series of physical and physiological changes such as lethargy, malaise, fatigue, social withdrawal, and even depression, to keep you inactive so you can recover from the illness.

A specific category of pathogens including the COVID-19 and Epstein–Barr viruses, the Lyme disease bacterium, and some molds and mycotoxins are able to enter the brain and infect the glial cells that surround the vagus nerve there. Inflamed glial cells secrete a lot of pro-inflammatory molecules, which may over-stimulate the vagus nerve’s sickness behavior signaling. Some scientists hypothesize that when this sickness behavior signaling loop gets stuck “on,” it contributes to the chronic inflammation and fatigue associated with these conditions. (Source)

The Vagus Nerve and Autoimmune Disease

The nervous system is responsible for coordinating immune responses, so it needs to be functioning properly to keep inflammation in check. The vagus nerve is connected to autoimmune disease via its direct role in balancing cytokines and turning on and off immune responses. (Source)

Normally, inflammatory cytokines are stopped by immune molecules made in the liver, spleen, and gut in response to vagus nerve signaling. If this healthy immune balance is disrupted, inflammation increases and autoimmunity may be the result. It's not surprising that vagus nerve dysfunction is frequently found in people with autoimmune diseases. One study found that 60% of people in a clinical trial with rheumatoid arthritis had vagus nerve dysfunction. Daily vagus nerve stimulation with an electronic device significantly reduced participants’ levels of inflammatory cytokines, helping with pain. (Source)

How To Stimulate The Vagus Nerve

Vagus nerve stimulation increases vagal nerve tone. Vagal nerve tone simply means your vagus nerve is good at turning on and off at the right times, which makes you more resilient to stress. Vagus nerve stimulation devices are small, wearable or implantable devices that use electric signals to stimulate the vagus nerve and may be used to treat conditions such as depression, epilepsy, and chronic headaches. (Source, Source)

That being said, the idea of vagus nerve stimulation is not new. Some techniques that have been recommended by functional medicine practitioners for decades can be done at home at home without medical devices. Century-old religious and cultural practices such as gargling and humming, for example, are purported to activate the vagus nerve.

Vagus nerve stimulation is meant to activate your “rest and digest” mode, which communicates a message of safety to your body that is conducive to healing. The following are some popularly recommended, traditional stimulation techniques.

Sing, Hum, Gargle

The vagus nerve extends through the throat and lungs, which is why singing, humming, and gargling are thought by some to stimulate it. Humming is an ancient meditative tradition, and it’s possible that it’s physiologically relaxing the nervous system via vagus nerve stimulation. The gag reflex is also controlled by throat muscles attached to the vagus nerve. Gargling water uses these muscles, and some believe it may stimulate the vagus nerve. Try gargling water or mouthwash for at least 20 to 30 seconds daily. (Source)

Take a Cold Plunge

Cold plunging has many incredible benefits for the body, including vagus nerve stimulation. Abrupt exposure to cold turns on a biological process called the diving reflex, which is a series of nervous system adaptations to cold temperatures that maintain homeostasis. The vagus nerve is part of this reflex – it has temperature sensors and some areas are directly activated by temperature change. The easiest way to do a cold plunge is by taking a freezing shower or bath. A dip in a chilly ocean or lake also works. The more regularly you can do cold plunges or expose yourself to cold water, the more often your vagus nerve will be stimulated. (Source)

Practice Breathwork

Simply relaxing can stimulate the vagus nerve, and breathing has a remarkable effect on your body’s sense of safety versus danger. Research has found that deep and slow  breathing turns on the parasympathetic nervous system, consequently stimulating the vagus nerve. You can do breathing exercises at a dedicated time everyday, or just when you feel stressed, though it's better to cultivate a regular practice that keeps you grounded.

Simply take 5 minutes to unplug and focus on your breath. Inhale through your nose for 4 seconds, trying to fill your lungs with as much air as you comfortably can. Hold this breath for a moment or two (you can build up as you go) then exhale for 6 seconds through your mouth as though blowing out candles. Squeezing your core muscles during your exhale is a great way to extend the time of your exhale. (Source)

Try a Polyvagal Exercise

Stanley Rosenberg is a cranial sacral therapist who wrote a book called The Healing Power of the Vagus Nerve. Part of his method includes using simple exercises that activate the vagus nerve and communicate messages of safety to the body. In doing so, the nervous system is redirected into a relaxed state. Try lying down with your hands laced at the base of your head. Take a few moments to relax and focus your attention to the presence of your hands behind your head, before moving your eyes to the right. Remain in this position until you either sigh, yawn, or swallow — this may take a few seconds or a few minutes depending on your stress levels.  

Spend Time in Nature

Many people feel calm and centered after going on a hike or even just lounging in a park, and there's science to back up why. Spending time in natural greenery has been shown to calm and regulate the autonomic nervous system, taking us out of fight or flight mode and into the vagus nerve-dominated healing state. Dedicating time to go for a walk in the woods, or even just sit and enjoy some greenery outside, are easy ways to calm your nervous system. (Source)

The Bottom Line on the Vagus Nerve

The vagus nerve travels down the body from the brain all the way to the digestive tract, making it one of the largest nerves in your body. It's a key player in the parasympathetic nervous system, and communicates messages of safety to your organs, changing how they function. This includes involuntary processes such as gut motility, blood pressure, immune responses, blood sugar, and mood. Stimulating the vagus nerve puts the body in a relaxed state, which promotes healing and can alleviate symptoms associated with chronic inflammatory conditions such as autoimmune disease. Incorporating at-home stimulation techniques into your daily routine is a great start to optimizing all the healing abilities of your vagus nerve. If you’re struggling with an autoimmune condition and looking for expert support to manage your stress and increase healthy habits, WellTheory’s Care Team creates personalized nutrition and lifestyle care plans that can help you reach your health goals.