( TIME.com ) -- Chances are you read this sentence about yawning and you yawned . Right ? Well , a new study suggests that you may not really be yawning because it 's contagious , or you 're bored or tired . You 're actually yawning because your brain is too hot . A group of researchers at the University of Vienna tested subjects in Austria and Arizona and tracked their activity , finding that that the only significant predicator of yawning was temperature : subjects were much more likely to yawn at higher temperatures . TIME : E-cigs still produce carcinogens . Other factors like sex , season , age , humidity , time spent outside , and hours of sleep the night before did not have a significant effect on the likelihood of a subject 's yawning . Ultimately , it appears that yawning is related to regulating brain temperature and creating a state where arousal in a yawner can be achieved . TIME : Science says stress is contagious . The idea is that if it 's hot , but still cool enough so that a large intake of air will bring your body temperature down , you 're in perfect storm territory for yawns . TIME : Carbon pollution could make your food less healthy .
A new study suggests we sleep because our brains are too hot . Researchers at the University of Vienna tested subjects in California and Arizona . Location , season , age , sex , time spent outside , and amount of sleep did not have an effect .