The Almighty Vagus Nerve

The vagus nerve is the embodiment of the phrase “mind-body connection.” Why is that? Because thats what it literally does. Its a cranial nerve that runs through the entire body, and through some smart manipulation, we can use this nerve to actually change what is happening in the brain. The vagus nerve demonstrates that sometimes the brain follows what the body experiences, and this is another angle through which we can boost our brain.

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You may have seen mention of the vagus nerve here and there, but what exactly is it, and what does it mean for your cognitive well-being? Rather than being a single nerve, the vagus nerve is more like a network of nerves that runs from the back of the neck down to the abdomen. The “vagus” is from the Latin (and it’s the same root as with words like vagrant and vagabond), and implies the nerve “wanders” throughout the body. It’s really a pair of nerves, one left and right, and each very long. In fact, this network of nerves is the longest cranial nerve in our body and connects most of the major visceral organs and the brain.

The vagus nerve coordinates an incredible array of functions—and it may be even more important than we first thought.

Stimulating the vagus nerve is associated with rest and relaxation, moderating our fight-or-flight response. Many now believe the mind-body connection has a lot to do with this nerve and how it can mediate between your thoughts and your feelings, your emotional state and your physical one.

It’s what makes people “trust their gut.” In essence, it links our brains to our bodies in a significant way, and we should pay attention to something that holds such a connective power.

The fascinating thing about the vagus nerve is its relationship with the breath; it responds primarily to one’s breathing rate.

When we breathe slowly and deeply, we don’t need our heart to pump as fast in order to supply oxygen to the rest of the body. When our breathing rate slows, it’s the vagus nerve that “tells” the heart to slow down to match. Stimulating the vagus nerve directly will have this effect on the heart, which in turn calms down and relaxes our entire body, dropping our heart rate.

The opposite of the “fight-or-flight” response (the sympathetic nervous system) is the less-discussed “rest-and-digest” mode, or more technically the operation of the parasympathetic nervous system. The stress response is mediated by stress hormones like cortisol and adrenaline; the relaxation response is mediated by the breath. Suddenly, the insistence of all those Zen masters to focus on the breath begins to make sense! This is an extremely useful piece of understanding: the relaxation response in your body can be activated directly by you, by modulating your breath. The vagus nerve will always adjust your heart rate to match your breathing. While you’re not in control ordinarily of your heart rate outside of doing cardio, you can impact your heart rate and many more internal processes, by directing your breath. Of course, this trends all the way up through the brain, reducing the cortisol and other stress hormones we experience, and clearing our minds for better and more energetic thought processes.

It’s a game changer. Instead of thinking your breath is shallow and rapid because you’re stressed, it may be more accurate to say that your body is stressing because it’s obeying the message of your breath. More specifically, it’s a longer exhale that triggers associated nerves that activate the relaxation response, and it’s during the exhale that your vagus nerve is most “active” (i.e. when you’re the most relaxed).

Professor of neurology Dr. Lucy Norcliffe- Kaufmann has been studying the vagus nerve and its effects on health since 2002.

Other researchers have determined in a 2001 study that we should all be ideally breathing around six times a minute, taking five seconds in and five seconds out for each breath. Their work focuses on yoga mantras or rosary prayer—not exactly activities that you associate with brain health, but the results are there! Rosary prayer, it turns out, encourages you to breathe at about this rate, as do certain mantras. Could the secret to deep relaxation and stress relief be as simple as daily prayer and mantras? Perhaps. The idea is to enhance what’s called vagal tone. Though we don’t often think about the health and well-being of our nerves, they can in fact show variation in tone, size and function, and we can “train” or tone our vagus nerve much like we can tone other parts of our bodies. Again, by this point of the book, you know that we can’t meaningfully compartmentalize our health and it all trends together, so your vagal tone is a huge contributor to mental well-being and the ability to boost your brain. When we have stronger vagal tone, it means a quicker return to calm and rest and digest, versus being flung all over the place and unable to regain balance.

Healthy vagus nerves are also crucial, for example, for the management of inflammation in the body. Some inflammation is normal and healthy, but too much is associated with diseases of all kinds, such as sepsis or a host of autoimmune conditions. In a 2007 review by Kevin Tracey, we see that when the body is inflamed, cells produce a protein called TNF, or tumor necrosis factor. This is a chemical message that the vagus nerve receives, and it responds by signaling the brain to produce anti-inflammatory chemicals that downregulate the immune response. In other words, the vagus nerve is like the thermostat dialing up or down the amount of inflammation in our tissues, warding off inflammatory disease while keeping our inflammatory response in a healthy range.

But this is just one of the many wonderful roles the vagus nerve plays. It turns out that it can also literally help you make memories. Researchers from the University of Virginia have found that vagus nerve stimulation actively improves memory. The vagus nerve is responsible for modulating the release of norepinephrine, which is known to consolidate memories in the amygdala. This has interesting implications for those trying to boost their brain power: relaxation improves memory, while stress impairs it.

The vagus nerve also stimulates the release of another important neurotransmitter, acetylcholine, which is involved in telling your lungs to breathe. A detailed review by Piccioto and colleagues outlines acetylcholine’s complicated relationship with the rest of the body—and with the vagus nerve. This is why some people recommend toning your vagus nerve by practicing holding your breath for up to eight counts, making shallow breaths a thing of the past.

The vagus nerve doesn’t only communicate via neurotransmitter, but can “talk” to the heart by sending electrical impulses to its own inbuilt “pacemaker.” Acetylcholine plays a crucial role in interacting with this region in the heart, thereby slowing its rate, according to a 2010 paper by Huston and Tracey. In fact, doctors can get an idea of your vagus nerve health (and your heart health!) by measuring your heart rate variability, or HRV.

It’s clear to most neuroscientists that the humble vagus nerve has widespread and vital functions throughout the body.

Boosting vagal tone is not just great for encouraging relaxation and cutting stress, it has measurable benefits on heart health, breathing and your memory function, to name just a few.

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Peter Hollins is a bestselling author, human psychology researcher, and a dedicated student of the human condition.

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