The reflex is good for your health:

Yawning doesn’t just relax youit quickly brings you into a heightened state of cognitive awareness. Students yawn in class, not because the teacher is boring (although that will make you yawn as well, as you try to stay focused on the monotonous speech), but because it rids the brain of sleepiness, thus helping you stay focused on important concepts and ideas.

Tell that to this Cornell professor.

(Hat tip: Frank Wilson)

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