Why Is Yawning Contagious? What a Brain Study Found
You see someone yawn and, a moment later, your own jaw stretches. This is called contagious yawning, and scientists still study why it happens.
An automatic response
A 2017 paper in the journal Current Biology describes contagious yawning as a common form of echophenomena: automatic imitation of another person's action or sound. It happens involuntarily when we see another person yawn.
What the Nottingham study did
Researchers at the University of Nottingham tested 36 adults. Participants watched video clips of someone yawning. In separate blocks they were told either to resist yawning or to allow themselves to yawn, and they were filmed so yawns and stifled yawns could be counted. The team also used transcranial magnetic stimulation (TMS) to measure the excitability of each person's motor cortex, the brain area involved in movement, along with a measure of physiological inhibition.
What they found
According to the paper's summary, three results stand out:
- Being told to resist yawning increased the urge to yawn and changed how yawns looked, with more stifled ones.
- That instruction did not change a person's underlying tendency to catch yawns.
- The TMS measures of cortical excitability and physiological inhibition were significant predictors of how prone a person was to contagious yawning.
The authors link this to a wider idea that echophenomena relate to individual differences in motor cortex excitability. They note these behaviors appear within a few weeks of birth and decrease after around age 3, which fits growing self-control and less automatic imitation.
What this does not settle
The study explains who is more likely to catch a yawn, not why yawning evolved or what yawning is for. It was a lab experiment with 36 adults. Trying not to yawn does not switch the reflex off; in this study it made the urge stronger.
Sources
- Brown et al., A Neural Basis for Contagious Yawning, Current Biology (2017): https://www.cell.com/current-biology/fulltext/S0960-9822%2817%2930966-1
Facts checked: October 9, 2026.