The vagus nerve has been a subject of fascination and mystery throughout history. In ancient times, Greek and Roman physicians believed that it helped regulate breathing and control the voice. In the Middle Ages, the vagus nerve was thought to be a spiritual channel between the body and the soul.
The vagus nerve was also believed to play a role in the production of tears, with the term “vagus” being used to describe a wandering person.
It wasn’t until the 19th century that the true nature of the vagus nerve began to unfold.
“Scientific studies began to provide more detailed insights into the functions of the vagus nerve,” said Megan Donnelly, D.O., lead neurologist and women’s headache specialist at Novant Health.
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.
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:
DizzinessAbdominal painAcid refluxDifficulty swallowingSpeech difficulty or hoarsenessLoss of appetiteWeight lossChanges in blood pressureMigraine attacksEpilepsyAnxietyDepression
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.
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.”
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.
Although we understand more about the vagus nerve today, there’s an aspect to it that is still, well, vague. For example, we don’t know if abnormal vagal tone is more common in women than in men.
“Overall, the relationship between gender and vagal tone is complex, and more research is needed to fully understand how these factors are related,” Donnelly said.
In the meantime, it’s always a good idea to move more — especially as we age. And we should keep in mind, when in the grips of anxiety, that our mothers were right all along: A cold compress on your forehead actually can help make it all better.