At first, it's just a feeling that seems to be sitting deep between the throat and ears. Then the mouth opens a little, and the lungs suck in air. More and more, the mouth widens in length, the eyes close, and sometimes tears come in, because the facial muscles press on the lacrimal glands.
Yawning for relaxation in everyday life
Yawning is actually a pretty unspectacular everyday thing. Especially when tired or bored, it comes involuntarily. That's 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 signal effect on others and controls the behavior of a group. Yawns one, then that means for all: Go to sleep. Researchers suspect that yawning is sometimes contagious for this reason.
Yawn as a reflex
Yawning is a reflex, that is, a recurring same reaction to a certain stimulus. What is the attraction and why people yawn, scientists are still puzzling.
For a long time, yawning was indisputably a reflex to a lack of oxygen in the blood, such as tiredness. The deep inhalation of the brain is actually better blood circulation, but American researchers have recently found that even with a very good oxygen saturation of the blood is yawned.
In people who breathed a mixture of air with increased carbon dioxide concentration, the respiratory rate increased, but they did not yawn more frequently. People who breathed pure oxygen also yawned as much as usual.
Also, there's yawning when we just read about it, hear about it or think about it. Studies have shown that every second one can be infected. Some respond in the first few seconds, others only after five minutes. This leads scientists to suppose that yawning has an interpersonal function.
According to researchers, only understanding and compassionate people are encouraged to yawn by yawning fellow human beings. Steven Platek from Drexel University in Philadelphia was able to prove in a study with video footage of yawning people the connection between a person's personality structure and his susceptibility to be infected by yawning.
It is possible that the common yawning unconsciously creates an opportunity to identify and ally with the other, the researchers suspect. Mentally ill people who can not empathize with others, such as schizophrenics, are not touched by the feelings of others; she also lets the yawning cold.
Not only humans, but also chimpanzees can be infected by the yawning of a conspecific. This was discovered by a British-Japanese research team investigating a group of six chimpanzee ladies. So far, contagious yawning was considered a purely human phenomenon.