What Is the Vagus Nerve?

What is the vagus nerve and what does it do? 

The vagus nerve is divided into two main branches — the left and right vagus nerves — and it travels all the way down from your brain through your neck into your chest and abdomen. This nerve is a critical element of our parasympathetic nervous system, the part of our brain that, to put it simply, calms things down.

“Think of the vagus nerve as the main nerve for rest and digestion,” Donnelly said. “It turns down the heart rate and blood pressure and causes digestion.”

The vagus nerve also regulates respiratory rate and some reflex actions like coughing, sneezing, swallowing and vomiting.

What happens when the vagus nerve isn’t working right?

When the vagus nerve isn’t functioning normally — also known as abnormal vagal tone — your health can suffer in many ways.

A vagus nerve that’s overactive, or too responsive, can cause fainting, decreased heart rate and nausea. An underactive vagus nerve can lead to rapid heart rate, decreased digestion and gastroparesis, a condition that keeps your stomach from emptying all the way.

Additionally, abnormal vagal tone, which is what it’s called when your vagus nerve isn’t working correctly, can cause:

• Dizziness
• Abdominal pain
• Acid reflux
• Difficulty swallowing
• Speech difficulty or hoarseness
• Loss of appetite
• Weight loss
• Changes in blood pressure
• Migraine attacks
• Epilepsy
• Anxiety
• Depression

An underactive vagus nerve is also linked to anxiety and depression. That’s why stimulation of the vagus nerve is sometimes used as treatment for these mental health conditions.

“There are multiple handheld devices [on the market],” Donnelly said. “They are held to the neck area and emit gentle electrical pulses.”

Autoimmune conditions may also be tied to a vagus nerve that isn’t working properly, although they might be the cause rather than the result of the malfunctioning vagus nerve.

“If anything, autoimmune disease can affect nerves throughout our body and the vagus nerve is the biggest and the longest,” Donnelly said.

Long Covid, for example, may trigger an autoimmune reaction, which can affect the vagus nerve.

Does icing the vagus nerve help anxiety?

Activating the vagus nerve has been shown to help reduce anxiety — at least in the moment of an anxiety flare-up. So, stimulating the vagus nerve during say, a panic attack, can help calm the body down.

The best way to stimulate the vagus nerve, which you can’t physically touch, is by exposing yourself to ice-cold temperatures.

“Cold water immersion has been shown, with some mixed results, to enhance vagal tone and improve HRV (heart rate variability),” said Sarah-Nicole Bostan, Ph.D., a clinical health psychologist who is board-certified in biofeedback. “The parasympathetic nervous system quickly kicks in, which results in slowed heart rate. This can feel grounding for a person experiencing the physical symptoms of anxiety, like racing heart and difficulty breathing.”

Ice is a great tool to make the vagus nerve kick in. Jennifer Surak-Zammitti, LCSW, a psychotherapist, recommends “icing” as an anxiety coping mechanism to her patients.

“When they’re feeling anxious, I will tell them to hold and squeeze ice cubes in their hand,” Surak-Zammitti said.

She also recommends icing to people at risk of self-harm.

“I tell them to hold an ice cube to their wrists,” Surak-Zammitti said. “It gives them the feeling of something on their wrists that they’re craving. It also buys them time to get to another coping skill to get out of the situation [that is] causing them to want to self-harm.”

If you’re feeling anxious, something as simple as super-cold air can help as well.

“If it’s winter, open a window and let the cold air hit your face,” said Surak-Zammitti. “It’s extremely calming.”

How can you improve your vagal nerve tone?

Vagal tone decreases with age (which you can’t help), but you can increase your physical activity. Research shows that exercise leads to a higher and healthier tone.

“This includes not just focusing on frequency of exercise, but gradually increasing intensity and length of time spent, and varying the type of exercises performed,” Bostan said.

Another way to get vagal toned: deep breathing. One recent study found that just five minutes of slow, deep breaths reduces anxiety and increases vagal tone.