Everyone yawns – babies, childen, teenagers, adults – but the truth is that we don’t completely understand why.
Many people think that we yawn when we’re tired or bored because our bodies are trying to get more oxygen to the brain. In 1987, Robert Provine from the University of Maryland decided to test idea. He asked groups of students to breathe different levels of oxygen for 30 minutes, and counted how many times they yawned. The result? All the students yawned about the same number of times.
So the traditional theory probably isn’t true. It also fails to answer a lot of other questions. Why do some illnesses make people yawn more? Why do Olympic athletes sometimes yawn before a rac? And what about ‘group yawning’ when people start yawning because they see other people yawning?
One study suggests we yawn when our brains are too hot. Yawning is simply a way of cooling the brain and helping it to work better. In the study, students were asked to watch videos of other people yawning, and the number of times they yawned in response was counted. It was found that the students yawned less often if they had something cold on their heads. People who breathed through their noses – another way of cooling the brain – did not yawn at all.
So it seems that we yawn not when we’re bored, but as a way of cooling our beains when we’re tired or tired or ill. ‘Group yawning’ probably started many thousands of years ago, when it helped small groups of people to concentrate and notice dangers.