why do you yawn when someone else yawns

You yawn when someone else yawns due to a phenomenon called "contagious yawning." This reflex is believed to be linked to empathy and social connection. Contagious yawning starts in early childhood when children develop empathy, which is the ability to understand and share the feelings of others. When you see someone you know well yawn—like a friend or family member—your brain "mirrors" their action, triggering you to yawn as well. Specifically, your brain has special cells called mirror neurons that activate when you observe someone doing something, like yawning, making you feel the urge to do the same. This mirroring helps build social bonds and synchronize group behavior, which may have evolved to enhance group vigilance and coordination. Another theory suggests yawning helps regulate brain temperature by increasing blood flow and bringing cooler air to the brain. When others yawn, it might signal that a shared environment is at a certain temperature where yawning helps cool the brain, prompting you to yawn too. Overall, contagious yawning has both physiological and social functions: it helps cool the brain and serves as a form of nonverbal communication that strengthens social connections through empathy and synchronized behavior.