The topic is sure to induce yawn in anyone who reads it with a cascading effect of yawning on people around. Science proves that anyone reading about yawn is bound to yawn. Yawning is found to be contagious and triggers 55% of people to yawn on the sight of somebody yawning. Researchers kept the yawner’s eyes open and the mouth covered and the invisible yawn caught other spectators yawning. So eyes too communicate yawn besides mouth. This is interesting to delve deep about yawn and the scientific truth behind yawning.
Yawn has been a subject of superstitions since the historical Mayan age. The Greeks and the Mayans believed that the mouth should be closed while yawning to prevent the soul from escaping through the mouth. Evidence suggests that the mechanism used by group of animals to communicate a change in the environment or body condition to each other in the group is termed as yawning. Contagious nature of yawn is attributed to be an ancient mechanism that lost its significance in the process of evolution. The exact reason for yawn is undetermined till now with various theories inconclusive to prove any condition as a possible cause.
For many years the lack of oxygen levels in the lungs were projected as reasons for yawning. Scientists have now proved that oxygen levels are not necessarily judged by lungs. Fetus in the uterus also yawns when the lungs are yet to be ventilated. These facts disassociate lungs as an organ that triggers yawning. Studies prove that yawning can be caused by fatigue, at the time of awakening and when alertness state changes in the being.
Yawn is a deep inhalation of air through the mouth that stretches the muscles of body and the jaw. All the animals yawn including humans, as an interaction of the brain and the body. Yawn is controlled by different regions of the brain and para ventricular nucleus in the hypothalamus of the brain is the “yawning center” of the brain. The yawning center contains chemicals like dopamine, oxytocin etc that raises its level in the night to awakening to induce yawn. Muscles involved in a yawn are not stretched when the yawn is stifled or controlled. The feedback to the brain on a stifled or controlled yawn retransmits an urge to yawn again proving that the yawn is a process that must involve deep inhalation of air with the stretch of muscles concerned.
Researchers found Autistic children reacted less to yawning compared to other children on seeing visuals of people yawning. Both the children yawned the same way when the video clip without the audio was shown identifying empathy can also be the key factor for yawning.