What is the Vagus Nerve?
First of all, the vagus nerve is the longest nerve in the body which originates in the brain as cranial nerve ten, travels down the from go the neck and then passes around the digestive system, liver, spleen, pancreas, heart and lungs. This nerve is a major player in the parasympathetic nervous system, which is the ‘rest and digest’ part (opposite to the sympathetic nervous system which is ‘fight of flight’).
The tone of the vagus nerve is key to activating the parasympathetic nervous system. Vagal tone is measured by tracking your heart-rate alongside your breathing rate. Your heart-rate speeds up a little when your breathe in, and slows down a little when you breathe out. The bigger the difference between your inhalation heart-rate and your exhalation heart-rate, the higher your vagal tone. Higher vagal tone means that your body can relax faster after stress.