| The reason that people yawn, is to equalize the pressure on your eardrums. So, the pressure change outside your ear offsets the people around you's eardrums causing them to yawn. The pressure change is only in the people in a short distance around you, but if the reaction continues for a long while, then you can get tons of people yawning. When you get tired, your body needs rest so that it can function properly. So when you are tired your "pressure control center" inside of your ear doesn't function properly. And when it doesn't function the pressure is offset causing you to, yup- you guessed it- YAWN! |
