The vagus nerve is a cranial nerve that activates the parasympathetic nervous system and increases levels of oxytocin and the calming neurotransmitter acetylcholine. Supporting the vagus nerve and thereby improving parasympathetic tone promotes relaxation, sleep, digestion, and healing.
Activating the parasympathetic nervous system dials down the sympathetic nervous system or fight-or-flight response. In that way, the vagus nerve acts as a built-in “stress-reset button.”
Heart rate variability (HRV)
An easy way to assess parasympathetic tone is to measure heart rate variability (HRV), which is the degree to which the intervals between heartbeats vary from heartbeat to heartbeat. You can measure HRV with a Bluetooth heart rate monitor combined with an app for your smartphone.
Higher heart rate variability (i.e. a less regular heartbeat) is associated with better digestion, reduced inflammation, increased emotional resilience, and a longer lifespan. High HRV means your parasympathetic nervous system is responding and adapting to your breath and other stimuli, and is a sign that your nervous system is in a state of resilience.
Lower heart rate variability (reduced vagal tone), on the other hand, is associated with negative mood and inflammation.
👉 Tip: The cervix is innervated by the vagus nerve, which is why the cervix is involved in achieving orgasm and possibly why some women experience anxiety from an IUD. (The statement about IUDs is only my theory at this stage. I welcome your comments.)
Link with altruism
Because higher vagal tone boosts oxytocin and feelings of altruism, some researchers refer to the vagus nerve as the love nerve or compassion nerve. According to Dr. Dacher Keltner, vagus activation is the source of the warm, expansive feeling in our chests when we experience (or even think about) human kindness.
7 ways to stimulate the vagus nerve and improve heart rate variability
You can calm your vagus nerve and parasympathetic nervous system by sending it signals of calm and safety.