Vagus Nerve

A very important nerve to know a little more about – especially for anyone suffering from stress, digestive issues and even some cardiovascular issues. We can help this nerve function better with breathing, humming or singing, as well as by massaging the ears.

Basically speaking the vagus nerve is involved in evoking a parasympathetic (generally speaking a calming) response in our organs. The vagus nerve is a modulator of the brain-gut axis and improving its function may help with some gastro-intestinal disorders. The vagus nerve also has an important role in increasing heart rate variability which is associated with reduced morbidity and mortality and improved psychological well-being and quality of life. The vagus nerve also enervates some of the muscles we need to engage socially (some parts of the ear, a small part of the tongue and the larynx).

Here’s a little more about this nerve and its importance in relation to stress for those who are interested:

The vagus nerve is one of our cranial nerves. It enervates many of our organs and affects our heart and breathing rate and our digestion. The vagus nerve is involved in a calming response.

Stephen Porges found that there are two parts to the vagus nerve, the dorsal and the ventral part and that both were involved in our reaction to stress. Stephen Porges called this the polyvagal theory.

Before the polyvagal theory, the action of the nervous system was generally described as a two-part antagonistic system: the sympathetic, more active (“fight-or-flight”) and the parasympathetic, more calming (“rest-and-digest”). It had also become understood that the parasympathetic system is not just the relaxing “rest-and-digest” response that we might be looking for in our breathing, meditation or mindfulness practices but is also part of our stress response as the “shut-down” or “freeze-or-faint” response. Have you or someone you know ever been so shocked that you could not move or react? Or maybe you have heard that some people faint with shock. That’s the freeze or faint response: it expresses as immobilisation or even dissociation.

So when we encounter a life-threatening situation, we can react via the sympathetic “fight-or-flight”, that is, we run away or punch our attacker, or via the parasympathetic shutdown, that is, we can’t react at all to what’s happening and freeze or even faint. Stephen Porges’ polyvagal theory identifies that we can also engage a third nervous system, the so called “social engagement system”. The social engagement system is a mixture of activation and calming. This mix is important when we face stress: after all, we do want to be able to still deal with the situation but we don’t want to be so active that we end up doing things we regret (say punch someone). We need to stay calm and collected whilst actively dealing with the situation.

Stephen Porges’ polyvagal theory shows that the different branches of the vagus nerve are involved in both the parasympathetic shut-down response as well as the social engagement system response. Shutdown is managed via the dorsal branch of the vagus nerve. The ventral branch of the vagal nerve serves the social engagement system.

The dorsal branch reaction to a stressful situation might feel like a bad flu with fatigued muscles and even some light-headedness. The dorsal branch also affects the heart and lungs and digestive system incidentally. The ventral vagal response to stress dampens the body’s active state, a bit like putting on the brakes gently to slow down a car. So the ventral vagal nerve allows stress activation but it moderates it. So it dampens any sympathetic activation and does so in milliseconds which means it can help us immediately.

Stephen Porges called this nervous system the social engagement system because the ventral vagal nerve affects the muscles involved in navigating relationships: he found that it was involved in some parts of the head; mainly the middle ear, that is the part that filters out background noises to make it easier to listen (have you ever been so stressed that you haven’t heard what is going on around you?), the palatoglossus muscle (a muscle of the tongue) and also the larynx, that is the area that controls our vocal tone and vocal patterning so that we can speak (ditto: have you ever been so shocked that your voice sounds hoarse?).

The good news from this: there are many practices that can help us to engage the social engagement system and help us moderate our stress response!