What makes us yawn?

Next time you're in a meeting, try this little experiment: Take a big yawn, cover your mouth out of courtesy, and watch and see how many people yawn. There's a good chance that you'll set off a chain reaction of yawns. Before you finish reading this question of the day, it's likely that you will yawn at least once. Don't misunderstand, we aren't intending to bore you, but just reading about yawning will make you yawn, just as seeing or hearing someone else yawn makes us yawn.

What's behind this mysterious epidemic of yawning? First, let's look at what a yawn is. Yawning is an involuntary action that causes us to open our mouths wide and breathe in deeply. We know it's involuntary because we do it even before we are born. Research shows that 11-week-old fetuses yawn
There are many parts of the body that are in action when you yawn. First, your mouth opens and jaw drops, allowing as much air to be taken in as possible. When you inhale, the air taken in is filling your lungs. Your abdominal muscles flex and your diaphragm is pushed down. The air you breath in expands the lungs to capacity and then some of the air is blown back out