Yawning has always been associated with sleepiness, boredom, or both but new studies are starting to point to a variety of other reasons behind the behavior. Though we often find ourselves apologizing for yawning, especially if we do it in socially situations where we are expected to be alert and attentive, the truth is that yawning may have little to do with our level of interest in the people that we are with or the content that we are listening to, and instead may be an unconscious response to stress or an attempt to keep ourselves particularly alert. It turns out that yawning is something that happens to nearly all animals, and it has a variety of causes and reasons behind it.
Gregory Collins is a researcher at the University of Texas Health Science Center in San Antonio who has spent extensive amounts of time studying yawning. He has found that when we yawn there are specific chemical responses at work in the brain. “What this tells us is it’s a very complicated system, and there are probably many different roles for yawning,” he says. Most people have heard the notion that yawning is a way for the body to get more oxygen. There is also a long-held belief that yawning is something that we do when we see other people yawn, and that it is a sign that we are empathetic. Neither of these theories is true, and to try to determine the exact causes scientists have been assembling data on when yawning happens, to whom, and under what circumstances. One thing that they have found is that people yawn more frequently during the summertime. They agree that people do yawn when they see others do so, but this is not always the case – infants and people with autism or schizophrenia do not participate in ‘contagious’ yawning. And many athletes or people who are about to engage in dangerous activities yawn immediately before beginning their action.
To figure out why all of this happens, scientists have been looking at both animals and people, and have arrived at a few conclusions. One is that when we yawn we are actually reducing our brain temperature back down to the correct, cooler temperature. When we are stressed or overly warm the brain can overheat, and this slows down our reaction times and diminishes our brain’s ability to remember things. Andrew Gallup, an assistant professor of psychology at the State University of New York at Oneonta, implanted probes into the brains of laboratory rats for a study he conducted in 2010. He found that yawning occurred after the rats’ brain temperatures rose a small amount, and that after the yawn the brain temperature fell back to its normal level. The same impact was found in a study done in Vienna which was published in the journal Physiology & Behavior, which found that out of a group of 120 subjects taking part in a study, there was far more yawning during the warmer summer months than during the winter.
Dr. Gallup says that when the body inhales cooler external air during a yawn, the blood is cooled and makes its way to the brain and lowers its temperature. He goes on to say that because stress and anxiety also increases our brains’ temperature, yawning serves to calm us down and help us to be able to operate more efficiently. This explains why so many people yawn before doing something important and stress provoking like giving a speech in front of a crowd or parachuting out of an airplane.
Another study that was conducted at Duke University School of Medicine eliminated the idea that yawning is contagious or an expression of empathy. A paper published in the online journal PLos One detailed a study in which researchers showed a video of people yawning to 328 study participants to determine what their reaction would be. Though about two thirds did yawn in response, the subjects’ answers to questions on a survey provided afterwards did not support the idea that they did so as a result of either fatigue or empathy. According to Dr. Liz Cirulli, an assistant professor of genetics who wrote the paper, age was a strong factor in whether somebody yawned or not, but even that had a minimal impact. “I’m hoping that means there is something genetic with the yawn response,” she said. She is continuing to research yawning, and is hoping to find a set of genes that makes somebody more likely to respond to other’s yawning.
Dr. Gallup theorizes that contagious yawning may be a social tool that keeps all members of a group alert. He published the results of a study in 2012 in the Journal of Comparative Psychology in which he and his colleagues observed the yawning of parakeets. When the birds were startled by a loud noise, the yawning that they exhibited became more contagious than in those who had not been frightened in the same way. He believes that the yawning may be related to “group vigilance,” and notes that group yawning happens more frequently in groups of animals that know one another or are related to one another than in animals that are strangers to one another.
From a chemical standpoint, researchers have identified specific changes that trigger yawns, including two types of brain receptors that both switch yawning on and off. Both work with dopamine, a body chemical that is generally at its highest levels early in the ay when we are waking up. Other studies have shown that yawning may have something to do with opioids in our systems, but most studies point to shifts in our body temperatures. Dr. Collins pints out that we yawn most frequently at night, when our body temperatures are at their highest, and suggests that those who are concerned about yawning during meetings and in learning settings should adjust the thermostat to make sure that a room is cool ad the brain doesn’t get overheated. “One way to diminish yawning frequency in an office would be to keep it air-conditioned,” he says. “If it’s very cold in the room yawning rates are going to be quite low.”