At first, it’s just a feeling that seems to sit deep back between your throat and ears. Then the mouth opens a little, and the lungs suck in air. Increasingly, the mouth widens lengthwise, the eyes close, and sometimes tears shoot in as the facial muscles press on the tear glands.
Yawning to relax in everyday life
Yawning is actually a pretty unspectacular everyday thing. Especially when tired or bored, it comes involuntarily. This is healthy: by yawning, the jaw muscles stretch and relax again, the heartbeat accelerates, our brain is better supplied with blood.
Social function in the animal kingdom
In the animal kingdom, yawning has a social function: it exerts a signaling effect on others and controls the behavior of a group. If one person yawns, it means everyone is going to sleep. Researchers suspect that yawning is sometimes contagious for this reason.
Yawning as a reflex
Yawning is a reflex, that is, a recurring same response to a particular stimulus. What the stimulus is and why people yawn are still puzzling scientists.
For a long time, yawning was undisputedly considered a reflex to a lack of oxygen in the blood, for example, when tired. Deep breathing does indeed improve blood flow to the brain, but American researchers recently found that yawning occurs even when the blood is very well saturated with oxygen.
People who breathed an air mixture with increased carbon dioxide concentration increased their breathing rate, but they did not yawn more often. People who breathed pure oxygen also yawned as much as usual.
Contagious yawning
What’s more, yawning is contagious if we just read about it, hear about it, or think about it. Studies have shown that one in two people get infected. Some react in the first few seconds, others only after five minutes. This leads scientists to suspect that yawning has an interpersonal function.
According to researchers, only understanding and compassionate people are encouraged to yawn along by fellow yawners. Steven Platek of Drexel University in Philadelphia was able to prove in a study with video recordings of yawning people the connection between personality structure of a person and his susceptibility to be infected by yawning.
It is possible that the common yawning unconsciously creates an opportunity to identify with the other person and also to form an alliance, the researchers suspect. Mentally ill people who cannot put themselves in the place of others, for example schizophrenics, are not touched by the feelings of others; even yawning leaves them cold.
Not only humans, but also chimpanzees can be infected by the yawn of a conspecific. This is what a British-Japanese team of researchers discovered when examining a group of six female chimpanzees. Until now, contagious yawning was considered a purely human phenomenon.
