<aside> <img src="/icons/light-bulb_blue.svg" alt="/icons/light-bulb_blue.svg" width="40px" /> The word "vagus" is Latin, and translates to "wandering"…
The vagus nerve is the 10th cranial nerve that connects the gut to the brain - branching (or wandering) into every major organ that falls between the two, making it the longest nerve in our body.
This summary will be detailed, but also simplified to only what is is necessary - so come with a fresh pair of eyes! It must just blow your mind...
Your body has two modes it likes to be in: "Fight or flight", and "rest and digest".
The sympathetic nervous system (SNS) is in charge of winding you up into fight or flight mode.
This includes the release of cortisol and adrenaline, all the while your body directs it's resources (like blood flow) away from what's not "essential" to what is.
I.e. What's not needed when running away from a lion, if you think about it evolutionarily - like the digestive system
So to repeat that, when your body is winding up or stressed, your digestive system doesn't work well because it's not an essential function in that state.
The parasympathetic nervous system (PNS) is in charge of winding us down into rest and digest mode - the vagus nerve makes up 75% of its fibres.
This includes the release of acetylcholine that regulates heart rate and blood pressure, intestinal peristalsis [what moves food through your intestines], glandular secretion, etc. (source).
In this state, the following also occur:
And more...
Both are part of the autonomic nervous system (ANS) that regulates our organs and helps us to stay in the right mode (fight or flight/rest and digest).
Now, to zoom in on the vagus nerve. In simple terms it's a communication line between the gut, the brain, and many of the organs in between.
The function of your vagus nerve is described as "vagal tone".
Well functioning vagus nerve = high vagal tone.
And a simple indication of your vagal tone is your heart rate/breathing.
Short-shallow breathes = low vagal tone.
Another indication is your ability to be calm. If you struggle to wind down, you may have low vagal tone.
Other signs of damage (low vagal tone) are difficulty swallowing, hoarseness of voice, poor gag reflex, and of course... gut issues!
A healthy vagus nerve can increase blood sugar regulation, reduced risk of stroke/cardiovascular disease, lower blood pressure, improve digestion, better mood, less anxiety, increase stress resilience, and more. (source / source)
What can you do to change your vagal tone?
Firstly, and the way I like to visualise it, train yourself to be calm in stressful situations (see this as flexing the muscle of winding down into "rest and digest" mode).
This includes cold water therapy - which also actives the Mammalian Drive Reflex that is designed slow our body down when diving into water - yoga (staying calm and controlling breathing in tough positions), as well as the following:
In addition, your body cannot sustain sympathetic activation - i.e. activation of the sympathetic nervous system, SNS (the release of adrenaline, cortisol, etc., putting you into fight or flight) - and in a world of relentless stimulation and stress, this can so often happen.
So the final point to take away with you, reduce and manage your day-to-day stress, and allow yourself time to wind down - especially in the hour surrounding eating.
A mantra that I ask all my clients to embody: When you're eating, only be eating. (No external stress of stimulation)
Books to continue building your knowledge: