Lowering the chin increases alertness, and raising the head leads to states of calm.

“Yeah, I love that you mentioned chin down because we all have a natural reflex when chin goes down, eyes goes up, and the opposite is true when head goes up, eyes go down. And there are two separate clusters of neurons in these cranial nerve nuclei that, as we call them, when eyes are up, it increases our level of alertness overall. This is not woo science, this is the function of these cranial nerve nuclei. When our eyes are down, we go into states of more calm and quiescence.”