The Vagus Nerve and Its Role in Our Body

The vagus nerve is the main conduit for the parasympathetic nervous system. 

This is the side of our autonomic nervous system that keeps the “fight or flight,” or sympathetic nervous system, in check. The vagus nerve originates in the lower brain and sends branches to our eyes, mouth, heart, lungs, digestive system, and other organs. When fired, it causes slowing of our heart rate, lowering of our blood pressure and blood sugar, and increased digestion, for example. Vagal activation also increases heart rate variability, a sign of a healthy cardiovascular system. It neutralizes the stress response associated with the sympathetic nervous system.

When we feel unecessarily stressed, we can activate the vagus nerve and assume a more restful, healthy state. Three ways we can activate the vagus nerve without using a special device involve ice, pressure, and the breath.

First, we can use ice to activate the vagus nerve. Perhaps the simplest way is to apply an icepack or bag of ice to our face. We can put the icepack over our eyes and upper cheeks. This works within a minute or two. Alternatively, we can submerge ourselves in an ice bath or cold water. The initial response to this might be sympathetic activation and the acute stress response, as the cold is rather shocking at first. Once we get over the initial shock, though, the cold water elicits the “diving reflex.” The cold water also represents a form of hormesis or “cold shock.”

We can also activate the vagus nerve by applying pressure over one side of our neck. The main artery in the neck, the carotid artery, has within its walls a structure called the carotid sinus. When the carotid sinus detects an increase in pressure, usually due to an elevation in blood pressure, it sends signals to the heart to slow down. This is a compensatory mechanism designed to lower the blood pressure. When we apply pressure over the carotid sinus we are tricking it into activating the vagus nerve to slow the heart rate. We can use an object, such as a softball, or we can simply use our fingers or palm to apply pressure. The pressure should be gentle and steady for several minutes.

Finally, we can activate the vagus nerve just by taking slow, deep breaths. This method is the simplest, most accessible, and perhaps safest of the three techniques. One way is to inhale to a slow count of 3 through our nose, then pause to a slow count of 3, then exhale very slowly to a count of 4 through the nose or mouth. Closing our eyes and repeating for at least 30 seconds is helpful. We can engage slow, deep breathing whenever we feel stressed.

Note: Although I am a physician, the content in this article is not meant to diagnose, treat, cure or prevent illness or disease in the reader – it is for educational purposes only.

References

• Good CB. Use of ice-water to obtain dive reflex. Am J Med 1992l;93(1):116.
• Goldberger JJ, Kadish AH, Johnson D, Qi X. New technique for vagal nerve stimulation. J Neurosci Methods 1999;91(1-2):109-14.
• Vanderhasselt MA, Ottaviani C. Combining top-down and bottom-up interventions targeting the vagus nerve to increase resilience. Neurosci Biobehav Rev 2022;132:725-29.