Why yawning is contagious?
Probably each of us has been in a situation where, looking at a person yawning, we opened our mouths. Scientists have proven that about half of adults want to yawn after someone else yawns because of a universal phenomenon called "yawn contagion." By yawning, we reflexively saturate the blood in our body with the necessary amount of oxygen, renew oxygen in the lungs, and relieve fatigue and stress.