Vagus nerve is responsible to sending signals from the body to the brain.
This means your whole entire body is mapped in the brain.
Skin and organs - need to be mapped.
Accupuncture - stimulates the skin. - this will send a signal.
When certain signals are sent - endorphins might be released in the brain.
I am guessing - these endorphins flush the brain in the specific area. Sort of like a reset.
http://www.healthline.com/human-body-maps/vagus-nerve
http://circ.ahajournals.org/content/118/8/863.long
http://drsircus.com/medicine/vagus-nerve-inflammation-heart-rate-variability
http://www.huffingtonpost.com/paul-spector-md/a-lot-of-nerve-the-antido_b_11302272.html
http://www.huffingtonpost.com/2015/05/29/hacking-the-nervous-syste_n_7469526.html
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4322601/
f Trigeminal Nerve Stimulation