Crowding is a reflex encountered in humans and animals alike, which consists of inhalation of air and the erection of the eardrum, simultaneously, followed by a strong exhalation. People start to grow up from the womb and generally associate with fatigue, sleep or boredom.
Although there are probably several factors that determine this reaction, there is not yet a universally accepted explanation to clarify why we are falling short.
The first studies indicated that the reflex would be a response to the increased levels of carbon dioxide in the blood when the body needs an oxygen supply that would warrant profound inspiration or carbon dioxide removal through strong exhalation. Subsequent experiments have shown, however, that low-carbon environments or oxygen administration of subjects do not influence the need to chew.
The latest theory claims that the role of yawning would be a thermoregulator. Specifically, the elevated temperature, which occurs naturally under fatigue, overload, or transition from state to state, slows down brain processes. Strong inspiration followed by exhalation leads to brain cooling and temperature control. This is the explanation for which men cry when they wake up and start their day, going from one state to another, when they are tired or before demanding experiences. Experiments prove that students are in front of exams, just like paratroopers, before jumping. Other explanations that explain why we fall away vary from the desire to stretch the muscles of the face and the tongue to the need to remain alert.
In some cases, but yawning can hide certain illnesses:
Pulmonary diseases. Craving can be a sign of chronic bronchitis and other lung complaints. "It's the case with smokers who poison their blood with carbon monoxide," explains Aurelia Constantin, an internist.
Diseases of the central nervous system. Other conditions that are manifested by yawning often are epilepsy, encephalitis, brain tumors and multiple sclerosis triggered by poor oxygenation of the brain. Studies have shown that drugs for depression or Parkinson's may have the same effect.
Heart diseases. It can be congenital malformations, such as septal defect, or heart failure. In both cases, the blood does not fully oxygenate. "In the case of a septal defect, the blood does not circulate in a normal direction, from left to right, but passes through a hole to the right of the left, bypassing the lung, and reaches the non-oxygenated general circulation. In case of renal insufficiency, the blood stagnates in the lower limbs ", explains Dr. Aurelia Constantin.