Thanks for the web site links - I really thought the one that pointed out that one theory is that people yawn when trying to stay awake, as I have trouble with this when meditating. Whenever I get the mind chatter to stop, then I struggle with staying awake. I know it's not from lack of oxygen, as one thing I have been good at is taking long deep breaths, although the point about breathing slowly can cause yawning also rings true. Very interesting stuff. I guess the best thing to do is let the yawns come, as by body probably needs it!
Thanks for all the responses.
Soli 
