Rubbing behind or inside the ears can activate vagus nerve branches to promote relaxation and parasympathetic activity.

“So, if you want to relax, you can rub behind your ears. You can rub inside your ears.”

“This branch of the vagus nerve that is carrying sensory information, doesn't come from the viscera or the neck. It comes from the head, and it's the branch of the vagus nerve that essentially goes behind the ear and in some of the deeper components of the ear.”