Yawning animals and small children are touching. For some reason, a yawning adult does not evoke such emotions, but at the same time, many people, when they see him, also begin to yawn. There is a lot of speculation about yawning, but even scientists still do not understand until the end: what is yawning and why does a person need it?
Healthyinfo figured out why we yawn?
What is a yawn?
Yawning is an involuntary action. In mammals, a yawn consists of several stages: opening the mouth, inhaling deeply, holding the breath for a fraction of a second (short apnea) and exhaling slowly. In time, one yawn lasts approximately 6 seconds. More than 90% of yawns occur at rest. In other cases, yawning serves social or emotional functions.
Birds and fish also yawn, but in a slightly different way than humans. They slowly open their mouth, hold it open for at least 3 seconds, and then quickly close it.
Many different substances are involved in the process of yawning — neurotransmitters, neuropeptides, hormones. For example, dopamine, acetylcholine, glutamate, serotonin, nitric oxide, adrenocorticotropic hormone (ACTH), oxytocin, and even steroid hormones facilitate and activate the process of yawning. And oppress, block yawning opioid peptides.
Not surprisingly, patients with Parkinson’s disease yawn significantly less frequently than healthy people. This is due to a lack of dopamine. It also becomes clear why people yawn in stressful situations: the stress hormone cortisol produced at this time causes yawning. This, by the way, explains why animals that have to be transported in cars yawn — no, they do not suffer from lack of air, they are just nervous.
There are several theories explaining why and why a person yawns.
The myth of yawning from lack of air
Even Hippocrates in the 4th century BC. argued that yawning is necessary for us to remove bad air from the lungs and increase the supply of oxygen to the brain. This is the most persistent hypothesis that has come down to our days.
In modern terms, this hypothesis sounds like this: when the brain experiences a lack of oxygen, the concentration of carbon dioxide (CO2) rises, and this leads to yawning.
However, during intense physical exercise, when the body clearly needs an increased supply of oxygen, people do not begin to yawn more often than at rest. Experiments with a high content of CO2 in the air also did not confirm this hypothesis. Against the background of oxygen deficiency and increased concentration of CO2, people began to breathe more often, and not yawn. Scientists have even confirmed that when yawning, the concentration of oxygen in the blood does not increase.
A person gets pleasure from yawning only if he opens his mouth. If he clenched his jaws in a polite way, he does not get a sense of satisfaction.
The myth of yawning and arousal
In search of evolutionary reasons for the formation of the mechanism of yawning, scientists have suggested that yawning is necessary to regulate the state of vigilance and is designed to excite the brain. Indeed, drowsiness causes yawning. Moreover, we most often yawn when we want to sleep or just woke up — that is, in moments of minimal alertness. Moreover, after yawning, as observations show, a person begins to move a little more intensively.
But this hypothesis was not confirmed either. No increase in brain excitation was observed. Sleepy, yawning people who for some reason can’t just go to sleep — for example, at an important meeting — do change their body position often, but solely because they are trying to maintain a state of wakefulness, and not because they felt like it in the process of yawning.
The myth of yawning and brain temperature regulation
Quite popular is the so-called thermoregulatory hypothesis — about “cooling the brain.” Its supporters believe that by yawning, a person provides an influx of cold air and cools an overheated brain. There have even been experiments that show how applying an ice pack reduces yawning and, conversely, a warm pack on the forehead increases the number of yawns. But here one nuance arises: the cold itself has an exciting effect, and heat causes drowsiness. So it is difficult to distinguish between the effects of temperature and yawning.
In addition, studies show that yawning shuts off normal nasal breathing, which is a much more effective way of ventilation than yawning.
Yawning and ear pressure
It is important for the human body to be able to equalize the air pressure in the middle ear with respect to the air pressure outside. Our body in modern conditions uses this skill when flying on airplanes and climbing in high-speed elevators — with a rapid change in altitude, the pressure in the middle ear increases, which causes discomfort and hearing impairment. It is enough to yawn heartily, as these sensations disappear, and hearing is restored.
How does this happen? To equalize pressure inside and out, the eardrum and stapedius muscles contract and relax. This leads to the opening of the Eustachian tubes and aeration of the tympanic cavities.
But even in this case, it turned out that the pressure can be equalized not only by yawning, but also by swallowing, chewing and the Valsalva maneuver (intense exhalation with the nose and mouth pinched). So the effect of yawning in this perspective is rather a pleasant side effect, and not a special evolutionary development.
Yawning and lung function
There were also a number of hypotheses that yawning prevents atelectasis (collapse) of the lungs, promotes the restoration of surface-active films in the lungs, and cleans the lacunae of the palatine tonsils. None of them have been proven.
Yawning and sleep
Since yawning does not turn on, perhaps, on the contrary, it reduces the level of arousal and prepares a person for sleep? No wonder we associate yawning with sleep. However, as the scientists report, “it was not possible to establish a causal relationship between yawning and drowsiness.”
Yawning and communication
Not discovering the physiological causes of yawning, scientists have taken up the social and communication side of human nature. The following assumptions have been made:
Yawning is a demonstration of hunger or mild psychological stress to others.
Yawning is used to synchronize group behavior. Translated into human language, this means that yawning is contagious.
The effect of “contagious yawning” is indeed confirmed by observations: it is enough for one person to start yawning for others to join him. Moreover, women are 2 times more susceptible to the yawning of others.
An interesting point: in patients with disorders of social interaction (autism and schizophrenia, for example), the susceptibility to someone else’s yawning is much lower than in an ordinary healthy person.
Until the age of 5, children do not have the phenomenon of contagious yawning — they do not start yawning at the sight of other people yawning. Scientists attribute this to the underdevelopment of empathy at this age. By the way, among animals, contagious yawning is observed only in species with developed empathic and communication skills: lions do not repeat their yawning counterparts, unlike empathic chimpanzees and adults.
One way or another, both theories are supported by the fact that watching people yawn or even listening to the sounds of a yawn activates areas of the brain associated with empathy, the ability to imitate other people’s movements, and social behavior. Also, when yawning, activity was noted in the ventromedial prefrontal cortex of the brain, namely this area is responsible for decision making.
Yawning and sickness
Is yawning a symptom of some disease? In the truest sense of the word, no. But something can be said about a yawning person.
So, we know that yawning is often observed before sleep and immediately after it, as well as in a stressful situation. This means that a yawning person may be under stress — even if he does not suspect it.
In a state of stress, the heartbeat quickens, blood pressure may rise — yawning does not cause these changes, but it can speak about them. Yawning can also serve as a marker of overwork.
By the way, yawning is one of the symptoms of an approaching vasovagal syncope, a condition associated with a sharp expansion of blood vessels against the background of a slowing heartbeat.
Yawning can develop in response to drugs containing either substances that activate yawning or substances that regulate their production. For example, patients with Parkinson’s disease begin to yawn more often when taking drugs with dopamine. Some antidepressants also cause yawning.
Yawn to orgasm
An unusual side effect was found in the antidepressant clomipramine. Some patients of both sexes, while taking it, began to experience an orgasm when yawning.
Yawning is still a mystery to scientists. So far, most researchers agree that this is a communication mechanism that has some side effects along the way. But any specific function that would be associated only with yawning and nothing else is still not possible to identify. And she certainly should be.