The vagus nerve may not be a topic that comes during casual conversation at brunch, but its role in our bodies is nothing short of extraordinary. This nerve -- which is actually a bundle of nerves -- stretches from the brainstem to the abdomen, and acts as a key regulator of vital bodily functions such as heart rate, digestion, and breathing. Functionally it’s like the body's built-in chill pill, helping us relax and restore balance when activated.