Open your mouth wide, stretch the muscles of your jaw and upper body, take a slow breath in, and then exhale quickly. What have you done? You have yawned. Many animals, including humans, yawn. They do ...

DEAR READER: We all yawn frequently, more often in the early morning and late evening. Does it mean we’re tired? Bored? Short on oxygen? As common as it is, we know little for certain about yawning.

It’s not obviously just mechanical, like a burp to release gas pressure, or just psychological, like a yelp to express fear or excitement. A yawn is more like a sneeze or a hiccup, an involuntary ...

Try not to yawn while reading this. (And yes, there's science behind why you yawn when other people do!) Fact checked by ...

DEAR DOCTOR K: I get plenty of sleep. So why do I yawn all the time? DEAR READER: We all yawn frequently, more often in the early morning and late evening. Does it mean we're tired? Bored? Short on ...