“Grin and bear it” usually signals discomfort. Grin so the world doesn’t know how bad the pain is.

But grinning can do more than that. Researchers now believe that smiling during brief periods of stress may help reduce the body’s stress response. Feeling happy has nothing to do with it.

For the study at the University of Kansas, 169 volunteers were invited to perform some multi-tasking activities, during which they held their faces in the manner instructed.

They found the participants who were instructed to smile, had lower heart rates after the stress activities than the ones who held their faces in neutral expressions.

That might explain why, when you smile, “the world smiles with you.” Maybe you’re simply feeling better about how much better you feel.