Yawning

Yeah but sometimes you yawn withint 1-2 hours of waking up even if you have had a good nights sleep.

during marching band camp we are out in hot sun (texas)
anyway i yawn like every 5 minutes
i think the scientist know his shitt

Hmm...maybe it's because your brain is just starting to warm up after cooling off all night? I don't know, I'm not a physician. I doubt that the head temperature thing is the whole story, especially since its contagiousness has been scientifically proven, and any full explanation of yawning would have to take that into account.