This works and is an accepted reason for yawning. Another indisputable cause of yawning is called social empathy. In fact psychologists have proven that the more empathetic you are, the more likely you are to yawn when someone else does. There has been fascinating research about the hierarchy of this suggestion. If you are very close to a person emotionally, you will yawn if they do. The rank order of this suggestion is family, friend, stranger.
The closer one is to the person who yawns, the more likely one is to yawn as well. Yawing clearly is associated with sleepiness and boredom. It is thus concluded that yawning may be a part of action repertoire of empathic and communicative processes in adult humans and some other mammals which provide for a strong social role of yawns in these species. Yawning relieves the ear discomfort and hearing problems that are commonly experienced by people during rapid altitude changes in airplanes and elevators.
This is achieved by opening of the eustachian tubes due to the contraction and relaxation of tensor tympani and stapedius muscles. An crucial experimental evidence that provides support to the above proposition comes from the work of Winther et al. The contrast material was detected in middle-ear by computerized tomographic scan of the temporal bone.
However, since the eustachian tube can also be opened by swallowing and Valsalva manoeuvre, thus yawning, by itself, does not appear to offer an indispensable evolutionary advantage of releasing middle ear pressure. The latter effect thus does not seem to be the primary purpose of yawning. For the past several centuries, a commonly held notion associated with yawning is that it is triggered when blood or brain oxygenation is insufficient, that is, when oxygen O 2 levels decrease and carbon dioxide CO 2 concentration rises.
However, this belief has been discarded in wake of the results of a recent study in which the yawning frequency was unaffected in subjects who breathed air mixtures containing either more than normal CO 2 or even pure O 2. Yawning research is intriguing because the ubiquity of this phenomenon across most of the vertebrate classes and even in a 20 week old human fetus,[ 9 ] suggest that considering it merely as an act of boredom and drowsiness is unjustified and that it may have a definitive underlying physiological importance which needs to be meticulously explored.
However, till we get a conclusive answer, it is safe to assume that yawning could represent a para-linguistic signal that may have multiple functional outcomes across various species. The authors would like to thank Robert R. Provine and Oliver Walusinski for their invaluable online archive of articles on yawning, which greatly facilitated the research for literature for this article.
Source of Support: Nil. Conflict of Interest: None declared. National Center for Biotechnology Information , U. Sharat Gupta and Shallu Mittal 1.
Author information Article notes Copyright and License information Disclaimer. Address for correspondence: Dr. E-mail: ni. Received Aug 20; Accepted Mar This is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.
This article has been cited by other articles in PMC. Abstract Although yawning is a commonly witnessed human behavior, yet it has not been taught in much detail in medical schools because, until the date, no particular physiological significance has been associated with it. Keywords: Arousal, brain thermoregulation, empathy, yawning. Footnotes Source of Support: Nil. Askenasy JJ.
Is yawning an arousal defense reflex? J Psychol. Provine RR. Yawning as a stereotyped action pattern and releasing stimulus. Am Sci. Simonds AK. Curbside consult: Why do people yawn? West J Med. Walusinski O. Popular knowledge and beliefs. Front Neurol Neurosci. Vick SJ, Paukner A. Variation and context of yawns in captive chimpanzees Pan troglodytes Am J Primatol. Front Evol Neurosci.
Caffeine effects on resting-state arousal. Clin Neurophysiol. Matikainen J, Elo H. Does yawning increase arousal through mechanical stimulation of the carotid body? As this theory goes, our bodies take in less oxygen because our breathing has slowed. Therefore, yawning helps us bring more oxygen into the blood and move more carbon dioxide out of the blood. Yawning, then, would be an involuntary reflex something we can't really control to help us control our oxygen and carbon dioxide levels.
Sounds good, but other studies have shown that breathing more oxygen does not decrease yawning. Likewise, breathing more carbon dioxide does not increase yawning. A yawn is an involuntary reflex where the mouth is opened wide, and the lungs take in a lot of air. The air is then exhaled slowly. During this time, the eardrums stretch, and the eyes may also close tight, causing them to water. No thought or action has to be taken to produce a yawn, and the process is similar for everyone.
Yawning commonly occurs either before or after sleep, which is why it is usually considered a sign of being tired. Yawning also occurs frequently in people who are doing boring or tedious things. There is also a social aspect to yawning. Yawning appears to be contagious among humans and other animals, and the contagiousness of a yawn is well documented but hardly understood.
There is no definitive reason for a yawn yet. Many proposed theories have surfaced and been studied, and they provide some clues. Yawning is commonly thought to be a sign of sleepiness or boredom, though this is not always the case. While someone who yawns may be tired, the heart rate quickly rises during a yawn.
This increased heart rate suggests yawning can be a sign of alertness rather than sluggishness. People may also yawn when changing physical states as well, such as moving from an area of high pressure to low pressure.
This pressure can build up in the eardrums and may cause the person to yawn to release it. Yawning may be a function of breathing.
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