Yawning is a natural reflex that doesn't seem to have any real use. And yet all vertebrates have yawned since the dawn of time: from humans to birds and fish , everyone is affected by this physiological behavior . Boredom , desire to sleep , mimicry or real need? We will show you that the role of yawning goes well beyond that and that it can even be an indicator of your state of health. We challenge you to read this article without yawning !
I. What are we talking about?
Yawning is one of the oldest behaviors of living beings that has been preserved through evolution and has remained completely unchanged.
This is a universal behavior since all vertebrates are affected: human beings , monkeys , horses , fish , birds , etc. Only the giraffe doesn't yawn . For what ? Quite simply because she has no real biological rhythm , given that she sleeps very little and very sporadically . Another surprising fact: it is in the fetal state that we yawn the most. Newborns also experience a significant frequency of this physiological phenomenon . Then, as we get older , yawning becomes less frequent. So, a healthy adult yawns 5 to 10 times a day for a total of 250,000 times over the course of a lifetime.
Everyone is therefore affected by this movement of opening the mouth which can be described as a reflex since it is involuntary . It is nevertheless possible to repress it more or less effectively or to modulate its intensity according to our will. This can be interesting, particularly if it occurs at a socially inopportune time, especially since it is often poorly perceived.
Let's dissect together the different stages of yawning which is in fact a succession of stretching and muscular contractions , a real respiratory cycle at its peak.
First, the deep breath .
The jaw stretches, the mouth is wide open to allow a large and deep inhalation of air. This gesture stretches the pharynx , which is the area of the throat connecting the nose and mouth . At the same time, the larynx , the tube that connects the throat to the trachea and contains the vocal cords , opens, spreading the vocal cords apart.
Second, brief apnea .
Once the thorax is filled with air , breathing stops briefly and the eyes close for a moment.
Third, slow exhalation .
The muscles relax and release air more or less noisily. The mouth closes and the larynx returns to its place.
These 3-step reflex muscle movements cause a temporary loss of hearing since the Eustachian tubes located in the ear canal open. The tear duct is compressed when the face is stretched , hence the sometimes observation of tears beading under the eyes .
II. Why do we yawn?
Ah the yawn ! Everyone has always yawned but no one knows exactly why, which has left room for various theories . Already, since Antiquity, interpretations were going well. Dear Hippocrates , our father of medicine , claimed that yawning allowed fever to evacuate, like a chimney. Then centuries later, it was the turn of Joannes de Gorter, a Dutchman, to pose his hypothesis . According to him, yawning increases blood circulation in the brain and as a result, the brain is better oxygenated . This belief remains rooted even today and many see it as true . And yet, this hypothesis is easily refuted. Indeed, it is at the fetal stage that the greatest number of yawns have been observed. However, at this stage, there is no contact with the oxygen in the air since the fetus is bathed in a liquid. In the same logic, fish also yawn, and yet it is not in the water that they can stock up on oxygen.
This is therefore an untruth. There are now more plausible explanations .
1 - Yawn to stimulate alertness during changes in pace
It is appropriate to first look at the situations in which we yawn . The majority of people will answer that we yawn when we feel tired or bored , or on the contrary in the morning when we wake up and stretch . Some even report this physiological behavior in situations of hunger or satiety, heat or illness. What all of these situations have in common is that they all lead to an increase in brain temperature . The most current theory is that yawning has a thermoregulatory effect by increasing arterial blood flow . Cooler blood would then reach the brain leading to cerebral cooling . Added to this is the hypothesis that yawning would promote the elimination of somnogenic factors accumulated over the course of a day in the cerebrospinal fluid. These two phenomena would increase alertness , particularly during changes in sleep/wake and hunger/satiety rhythms.
2 - Yawn to stimulate release from stress
People who skydive say they tend to yawn before they jump. Police officers say they yawn before getting into a difficult situation. These different testimonies made it possible to determine a key factor which triggers yawning : anxiety ! Because these three-step breaths have the incredible power to bring back serenity to calm stress .
Yawning has even become a therapy recommended for actors before a show, for athletes before a competition or for students before an exam. A method that has no equal for relax and release tension !
3 – Yawn to express your desire
During the macaque population study, scientists had already made a surprising discovery : the dominant male of a group yawns loudly several times before mating . And, surprisingly, if it loses this status, the behavior disappears.
Still according to experts, in humans , yawning accompanied by stretching is an expression of sexual desire for women.
The yawning-sexuality link has not yet been clearly established but observations show that it exists and that it serves as non-verbal communication at the time of the act.
4 – Yawn by mimicry to show empathy
We have all already experienced it. In a work meeting, or with family or friends, when someone yawns , we yawn . Besides, you may be yawning while reading this article! This is probably the phenomenon where the contagion is the most important. This mimetic behavior has been observed even in animals . For example, dogs yawn in response to the sight of their owners, or even strangers. But how can we explain this curious movement of replication ?
The scientists therefore looked at the brains of humans using a medical imaging system when they witnessed a person yawning . They were surprised to find that areas of the brain involved in social function were activated at that moment. What does that mean ?
The interpretation would be that yawning is an act of nonverbal communication.
Primarily, the one who yawns would signal to the rest of the group his state and the current experience of a moderately unpleasant experience without being an immediate threat: for example the heating of his brain and his subsequent loss of vigilance , his fatigue or his hunger . This would allow the group to synchronize activities meeting vital needs (eating, sleeping).
Yawning in return would in fact be a visual and auditory response: “I was able to adopt your point of view, decode your emotional state and experience what you feel . I can put myself in your place and in the same state as you”. This is the theory of mind . Contagious yawning would therefore be correlated with empathy and compassion .
This mimetic mental ability specific to primates has been observed in humans , great apes , elephants , parrots , etc. It is interesting to note that not all of us are endowed with this capacity for compassion. Only three quarters of the population are sensitive to yawning , especially since an emotional bond binds us to this person . Indeed, and you will no doubt have noticed, someone close to you is more likely to make us yawn than a stranger. You will be surprised to learn that this contagion phenomenon decreases with age (and not because we become less empathetic over time!). Thus, those under 25 are more receptive to communicative yawns than 26-50 year olds , who are themselves more receptive than those over 50 .
Also fun information : advertisers showed in the 1960s that the people most sensitive to others' yawns are also the most receptive to advertising, the exact cause and effect remains to be deciphered...
III. Yawning, an indicator of health?
“Yawn until your jaw drops”, yes, it’s possible. It has happened that some yawns that are too wide have unhinged the jaw of some unlucky people with dislocation of the mandible or temporomandibular. Yawning can therefore be somewhat dangerous. But did you know that by being vigilant about the frequency of your yawns , you could make unexpected connections with your state of health ? Indeed, certain illnesses or treatments intensify them or space them out.
If you do not yawn or yawn very little, this may be due to Parkinson's disease or the use of neuroleptics ( opiates, drugs ).
On the contrary, if you reach 50-200 yawns per day in bursts of 15-20 , you may be experiencing the side effects of selective serotonin reuptake inhibitor anti-depressants.
Also, an increase in this reflex phenomenon can be linked to the presence of cranial hypertension linked to the presence of a tumor , to a neurological disease , to forms of epilepsy , to multiple sclerosis , etc.
Less serious but no less restrictive, the multiplication of this oral muscular movement can be a harbinger of a migraine .
Finally, even if they can announce bad news in terms of health , they can also prove useful for regulating pressure problems . For example to unblock the ears at altitude and release the compressed nerve during barotraumatic facial paralysis (after coming back from scuba diving).
Whether to increase alertness, reduce stress, communicate non-verbally, or indicate your state of health, yawning turns out to be unsuspected allies in your everyday life. Research continues and we are not immune to discovering other surprising roles of this natural behavior that we all adopt . To improve your alertness, you can also use Work & Play and to reduce your stress, don’t hesitate to try Life & Balance 😋