The vagus nerve is the most important element of the parasympathetic nervous system (the one that calms you down by controlling your relaxation response).
It originates from the brainstem and it is “wandering” all the way down, into the belly, spreading fibers to the tongue, pharynx, vocal chords, lungs, heart, stomach, intestines and glands that produce anti-stress enzymes and hormones (like Acetylcholine, Prolactin, Vasopressin, Oxytocin), influencing digestion, metabolism and of course the relaxation response.
Vagus nerve acts as the mind-body connection, and it is the cabling behind your heart’s emotions and gut instincts. The key to manage your mind state and your anxiety levels lies on being able to activate the calming nervous pathways of your parasympathetic system.
The vagus nerve can be stimulated many ways but one of the easiest ways is through "belly breathing".
On the other side it creates pressure, pushing the viscera down and out, expanding your belly. That’s why good breathing practice is described as abdominal breathing or belly breathing.
To take vagus nerve stimulation a step further, breathe with the glottis partially closed. Glottis is at the back of your tongue and it is closed when you are holding your breath. Here we want have it partially closed. It is that feeling you have in your throat while you exhale and make a “Hhhhh” sound in order to clean your glasses.
Eventually, when your newly acquired breathing skill is established and abdominal breathing becomes a habit, you’ll find your body constantly operating at a much lower stress level.
You will also notice (or sometimes you will not even notice it) how your breath responses to stressful situations; your body will be conditioned to automatically control your breath and by this, your stress and anxiety.