Why do I keep yawning throughout the day?

Main reason for yawning is the body needs a mive dose of oxygen because you are not giving it what it needs at certain times during the day. There are 2 core reasons for not breathing properly. Poor posture eliminates one of the causes (won't give you the cause because most just deny it) and eliminating stress waxes the other! Fear and stress cause people to hold their breath. Not like for minutes, just a few seconds, enough to make you yawn. I was stressed in school all the time and ended up like you yawning all day long. (I slept like a rock but only for 5 hours a day) A simple note on the hand to do 5 deep breaths every time I looked at the note fixed it to the point I forgot about the problem. Make a reminder. By the way the by-product of 5 deep breaths many times a day was a gain of 1 1/2 grades! I started to get a "B"+ average in my final days of school. Freaky cool!