vagus nerve
The vagus nerve is a bundle of nerve fibres in your body. It runs from the brainstem down through the neck and into the chest and abdomen. It branches out to the heart, lungs, airways, stomach, liver, intestines, and most of the digestive tract. It is the longest cranial nerve in the body.
Roughly 80% of what it carries is sensory information travelling upward. The vagus nerve reports to your brain about what is happening in your organs.
In recent years, the vagus nerve has become a fixture of wellness content. Many techniques, including cold showers, humming, and gargling, are promoted as ways to “stimulate” or “tone” it. Some of this is supported by research, but many of the easy-fix claims are exaggerated. And for neurodivergent people in particular, some of the advice is actively unhelpful.