A happy vagus is a happy human; a happy human is a happy world.
The vagus nerve is the primary communicator of the brain to the parasympathetic nervous system, responsible for the relaxation response, and to the sympathetic nervous system, the fight, flight, or freeze response. It's the largest cranial nerve in the body, beginning at the base of the skull and extending throughout the body.
We take the vagus nerve for granted when we’re feeling balanced; it’s when it’s not functioning that we notice the effects: feelings of depletion, sluggish digestion, increased heart rate, erratic moods. A poorly functioning vagus nerve can be part of depression, PTSD, chronic pain, and epilepsy.
New studies are suggesting that the vagus nerve might work with oxytocin receptors, the neutotransmitter of bonding feelings. People with higher levels of oxytocin are prone to feeling emotions that promote altruism – compassion, gratitude, love, and happiness.
The great news is that its easy to stimulate the vagus nerve. Just breathe! When you take a deep, conscious breath and expand your diaphragm, it stimulates your vagus system. You instantly turn on your parasympathetic nervous system, cortisol (the stress hormone) levels drop, and your body relaxes.
Breathe slowly in and out through the nose. Gradually slow the pace down, then begin make the exhale longer than the inhale.
Chanting OM out loud increased vagal tone, according to one study.
A sensation of vibration is experienced during audible 'OM' chanting. This has the potential for vagus nerve stimulation.
Sources:
http://spirittrail.wordpress.com/2012/12/15/its-10pm-do-you-know-where-your-vagus-nerve-is/
http://genes2brains2mind2me.com/2011/01/03/whyi-ujjayi/
http://www.swamij.com/diaphragmatic-breathing.htm