Why are yawns contagious?

Yawns are contagious because our brains often copy the actions we notice in other people. Scientists are still studying the details, but one strong idea is that seeing a yawn starts a matching movement pattern in your own brain before you have much say in it.

The sweetest clue is that caught yawns are linked with social connection. Older children and adults tend to copy yawns more than very young kids do, and people often catch them more easily from someone familiar, which may connect yawning with empathy.