Thus, contrary to our impression that yawning is rude and insulting, Dr. Gallup asserts that “yawning is really a compliment, because it suggests that brain mechanisms have kicked in to reinstate and optimize mental processing.”

Therefore, yawning helps us bring more oxygen into the blood and move more carbon dioxide out of the blood. Yawning, then, would be an involuntary reflex (something we can't really control) to help us control our oxygen and carbon dioxide levels.

Does yawning indicate a lack of oxygen? Researchers initially thought that yawning might mean you lack oxygen, but more recent evidence suggests this is untrue. Yawning doesn't mean you lack oxygen or your body is trying to get more oxygen.