People have been saying this for years, but we are daily gaining more scientific evidence to back it up. Here’s a University of Maryland School of Medicine study that shows—ta-da–laughter helps blood vessels function better.

Seems the endothelium (lining of the blood vessels that helps maintain their tone, regulates blood flow, controls thickening and helps heal wounds) expands when you laugh. Stress does the opposite. In fact, the study concluded that laughter has approximately the same effect on your system as aerobic activity!

So instead of worrying that your employees are wasting time, let ’em keep those email jokes comin’, folks.