mystery of yawning
Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
 
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal
Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
 
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal
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mise à jour du
26 décembre 2011
Orv Hetil.
2011;152(42):1707-1710.
Yawning, Sleeping and Dreams
Jakobovits Akos and Jakiobovits Antal
 
Translation by Wolter Seuntjens

Chat-logomini

 
Mankind has always been intrigued by sleep and dreams, and has researched their importance. Interpretation of dreams and their importance has created a whole new "profession". Sleepiness and yawning precede sleep, therefore yawning, sleeping and dreams are actions directly related to one another. Yawning is an action seen at every stage of life, from early embryonic to old age. (Fig. 1). Yawning is also seen among animals: in mammals, birds and reptiles (Fig. 2). This behaviour leads to the conclusion of a common forefather, from which the different species have evolved, keeping certain behaviours, like yawning, despite their evolving in different directions.
 
Ontogenetically yawning is involuntary, and a stereotyped behaviour, therefore it is considered a physiologic reflex. The reflex uses: the hypothalamus, the brain stem reticular net (Formatio reticularis), portion of respiratory neurons in the medulla, parts of motor nerves V, VII. IX. and X, the Nervus phrenicus and the intercostal nerves.
 
Yawning and mouth/facial movements are controlled by the V. and VII. Cranial nerves. In utero yawning differs from mature yawning, since the tongue is extended. The opening of the mouth can be seen from the 10th week of pregnancy, whereas the mouth-reflex is seen in the 18th week. Until the 15th week the wide opening of the jaw is more regular than later. The irregular repeated movements are however seen more often after the 15th week, than before. The opening of the jaw can happen solo, or be accompanied by hickups or isolated movements of the head.
 
The embryo tilts its head backwards, and only then opens its mouth. The neck and the mouth are slightly extended, and then retracted. The tongue is meanwhile pushed down and to the back of the mouth. The extended wide opening of the mouth takes two to eight seconds followed by a quick closing of the mouth (4, 5, 6, 7). The opening of the jaw can be slow or fast. Sometimes concommitant lifting of the arms can be witnessed, while the head ante flexes, the tongue retracts and the mouth shuts quickly. This takes place within one to five seconds, and can happen once, or repeatedly. Normal embryos will yawn 5 times an hour, sick, retarded or anemic will yawn more often.
 
Yawning also has some suggestive effect. If one yawns, others present at the scene will yawn too, regardless of whether he is tired or not. It is interesting to note that yawning can occur during sleep (Fig.3). Sleep plays an important role in our health and in our life. Significant parts of our life are occupied by periods of sleep. The younger the subject, the longer the sum of the periods of sleep will be. Embryos will spend about 40% of their time in the womb sleeping (Fig. 4). Once born this decreases, but still a significant amount of time is spent sleeping. The elderly sleep the least. The ancient Romans were already aware of the importance of sleep in their lives. They left us the saying: "sex horas satis est" (six hours are sufficient), but they did not count the after-lunch nap.
 
 
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