" The ability to calmly speak with one’s spouse as to the whereabouts of the espresso tamper means asking the autonomic nervous system to perform two contradictory goals at the same time—and the key to that, says Porges, is the vagal brake. The vagus nerve links up all the tools we need to respond to an existential threat, and so the vagal brake is a signal sent through the system for everything to stand down and engage—at ease. And it turns out there is a simple measure "

― John J. Ratey , Go Wild: Free Your Body and Mind from the Afflictions of Civilization