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If you yawn while reading this, it’s probably not because you’re bored. A team of researchers in Austria may have uncovered the answer to one of science’s most perplexing questions: Why do we yawn? Instead of yawning to get more oxygen into our lungs, or to signal that we’re tired or bored, the new study suggests that yawning may actually help the brain to cool down.
The researchers tracked the yawning behaviors of 120 Austrian volunteers in both the winter and the summer seasons. They asked the volunteers to look at pictures of people yawning, and then had them fill out surveys about how often they yawned or wanted to yawn while viewing the pictures, how much sun exposure they’d had before the survey, how much they had slept the night before and their age. At the same time, researchers measured the air’s temperature and humidity. Volunteers were also asked questions about their usual yawning habits.
The researchers found that temperature was the only consistent predictor of how much people yawned. While 41.7% of Austrian participants in the summer yawned during the experiment, only 18.3% of people in the winter did. Participants also reported yawning more during the summer than the winter. The people’s gender, age, the outdoor humidity, the amount of time they’d spent outside and how much sleep they had gotten did not affect how much they yawned.
