Why are yawns contagious?
In fact, even researchers are divided on the answer.No one knows for sure why yawns are contagious. A well-known idea links it to empathy, the ability to sense how others feel, and research shows yawns spread more easily from people we are close to, like family and friends. However, another study of more than 300 people found no strong link with empathy.
Caught yawning
Have you ever seen someone yawn and then found yourself yawning too? That is what we call a contagious yawn. It is not just people: yawns are known to spread among chimpanzees as well.
The closer, the more contagious
A research team at the University of Pisa in Italy observed adults yawning over 1 year. They found that yawns spread most easily from family, then friends, then acquaintances, and least from strangers. The closer the person, the more easily the yawn spread, and the faster it followed. Because this order matches the pattern of empathy, they concluded that catching yawns is linked to empathy. In a study at Emory University in the United States, 23 chimpanzees yawned 50% more after watching members of their own group yawn than after watching chimpanzees from another group.
The band widths only show the order, not actual rates.
No link to empathy?
However, a 2014 study by Duke University in the United States found something a little different. When 328 people watched a 3-minute video of people yawning, the number of yawns varied widely, from 0 to 15, and 222 people yawned at least once. Yet no strong link was found with empathy, sleepiness, intelligence, or the time of day.
Most of it is still a mystery
The only factor linked to contagious yawning in this study was age: older people tended to catch yawns less. Even so, age explained only about 8% of the differences between people. The researchers said most of the reasons remain unexplained, and they believe studying how yawns spread could offer clues about how the human brain and body work.
Want to know more?
- In the Duke study, the number of yawns stayed about the same for each person across repeated tests, showing that how easily someone catches yawns is a fairly stable trait.
- In the Pisa study, gender and nationality were not related to how easily yawns spread.
- The researchers who studied chimpanzees think yawns are contagious for the same reason that smiles and frowns are.
Quick quiz: test yourself
Whose yawns are you most likely to catch?
Show the answer
- A stranger's
- A family member's
- An acquaintance's
A family member's In the University of Pisa study, yawns spread most easily from family, then friends, then acquaintances, and least from strangers.
In the University of Pisa study, yawns spread most easily from family, then friends, then acquaintances, and least from strangers.
Next quiz ›Sources
- Contagious Yawning May Not Be Linked to Empathy; Still Largely UnexplainedDuke Health（デューク大学）
- Yawn Contagion and Empathy in Homo sapiensPLOS ONE（ピサ大学）
- Ingroup-Outgroup Bias in Contagious Yawning by Chimpanzees Supports Link to EmpathyPLOS ONE（エモリー大学）
- Chimpanzees' contagious yawning evidence of empathy, not just sleepiness, study showsEmory University（ScienceDaily 掲載）
This article was written after checking the sources above as of 2026-10-03. Explanations may change as research progresses. Photo credits are shown below each photo.
