Have you ever yawned after seeing someone else yawn? Yawns can spread from person to person. You may even yawn when you read the word "yawn." A study in Italy found that yawns spread most easily between family members, then friends.

Some chimpanzees also yawn after watching others yawn. Young children catch yawns less often than adults. Some people think this shows empathy. But scientists say there is not enough proof yet.

Yawning is surprisingly contagious. Seeing, hearing, or even reading about a yawn can make people yawn. In 2011, two researchers in Italy observed people in daily life for about a year. They found that yawns spread most easily among family members, followed by friends, acquaintances, and strangers.

Because of this, some scientists suggested that contagious yawning is linked to empathy, the ability to share other people's feelings. Some chimpanzees also yawn after watching videos of other chimps yawning. However, in 2017 other researchers argued that the evidence is not strong enough. How easily we catch a yawn also depends on age, sleepiness, the situation, and where we pay attention.

Seeing someone yawn, hearing a yawn, or even reading about one can set off a yawn of your own. Scientists still argue about why we yawn at all. The old idea that yawning raises oxygen levels has little support. One leading hypothesis, proposed by Gallup and colleagues, is that yawning helps cool the brain.

Why yawns spread from person to person is a separate question. In a 2011 study, Norscia and Palagi watched people in everyday settings for about a year. Yawns spread most readily among relatives, then friends, then acquaintances, and least among strangers. To some researchers, this pattern suggested that contagious yawning reflects empathy. Chimpanzees seemed to back the idea, since some yawn after watching videos of others yawning, and so did the fact that young children rarely catch yawns.

A 2017 review by Massen and Gallup disagreed, arguing that treating contagious yawning as a measure of empathy is premature. In natural settings, people may simply spend more time looking at the faces of loved ones, so attention could explain the pattern as well as empathy can. Age, sleepiness and context also affect how easily a yawn spreads.