Why do we yawn?
Found an interesting article on this... Yawning is a unique breathing act, which is different from the usual practice of breathing. During yawning, the mouth involuntarily opens due to the spasm of mastoid muscles. These spasms, without your permission, force you to take a deep breath. It also involves many other muscles of your body, such as abdominal muscles. Lung ventilation increases, sending oxygen to the brain. Extra blood is pushed from the liver and spleen to the brain stem. During yawning, intellectual activity stops and for a moment we cannot think. We usually start yawning when we are very tired, before sleep, when we are too excited, or extremely serious. There is a yawn center in our brain that makes this act a reflex like coughing or swallowing. The yawning reflex is very contagious, forcing people to imitate it. This phenomenon even has a fancy name: alolomimea. Yawning can be easily conditioned to become a bad habit. If you fight the urge to yawn, it will return in a similar situation. Yawning is what your body develops to get a “time out” to recharge for a brief moment. It is a signal that we are running out of gas, it is a signal to rest. This is a great compensatory mechanism, without which we would drop into sleep suddenly without warning, as in patients with narcolepsy.
Why do we yawn ?
They really don't know. But according to a brain book I've read this is what it said about yawning: "Yawning isn't what it's cracked up to be. Monica Greco, a psychologist at Rowan College in Philadelphia, and Temple University psychologist Roy Baenninger have spent years observing yawning in humans and animals. They have concluded that predators yawn much more than herbivores. Herbivores have less need to stay aroused, because their diet is a stationary target, whereas predators must stay very alert in order to capture prey and to avoid being captured. Compare the relatively laid back plant-eating giraffe who doesn't yawn at all, to the frequently yawning ever-active lion. In a November 22, 1994, Knight-Ridder release, Greco and Baenninger describe yawning as a method of self arousal, and not as a sign of sleepiness. The yawning response appears to be triggered when dopamine falls below acceptable levels in the brain. The yawn exercises jaw muscles that affect the flow of blood to the brain. A good yawn reoxygenates the brain, leading to increase arousal and alertness. Evolutionarily, yawning is nature's way of priming the brain out of low arousal when things are boring but it's dangerous to be inattentive to what's going on. Enjoy your yawns and don't be embarrassed that people may thing you're sleepy. Consider a yawn to be nothing more than your )and others') right to a jolt of fresh air. Others should, in fact, consider your yawns as a compliment--after all, you're trying to remain maximally alert for the!" That ought to help.
Why do we yawn?
Scientists do not purport to know all of the biological mechanisms of the yawn, but tend to agree that a yawn is an involuntary respiratory reflex, which regulates the carbon dioxide and oxygen levels in the blood. Technically, a yawn is the reflex opening of the mouth followed by the deep inhalation and slow exhalation of oxygen. The very act of yawning is but one of a number of involuntary reflexes controlled by the spinal and nerve centers. Scientists speculate that the onset of a yawn is triggered either by fatigue, or by sheer boredom as, at those times, breathing is shallow, and little oxygen is carried to the lungs by the oxygen-toting cardiovascular system. When one yawns, his or her alertness is heightened, as the sudden intake of oxygen increases the heart rate, rids the lungs and the bloodstream of the carbon dioxide buildup, and forces oxygen through blood vessels in the brain, while restoring normal breathing and ventilating the lungs. This quite plausible theory of yawning falls short of explaining many aspects of yawning. Scientists explain away the "contagious" nature of yawning, that is when one person's yawn triggers another nearby to yawn, as due to the power of suggestion, but are at a loss when attempting to explain why yawning occurs excessively in patients with lower brainstem damage or with multiple sclerosis. http://www.coolquiz.com/trivia/explain/d...
Why do we yawn?
Yawning is involuntary reflex of the body to balance carbon dioxide and oxygen in your body[1][2][3][4] .When we get tired or bored, we breathe slowly and thus the level of oxygen in our body drops. Yawning is the involuntary reflex as a result of this imbalance in body.Another theory as suggested in the footnotes is that by yawning we stretch our lungs which results in stretching of our muscles and thus may make awake.Another theory is that yawning helps us redistribute oil like substance called surfactant which keeps our lungs lubricated.Another theory is that it causes us to stretch our jaws which results in increased blood flow to neck and face.Another theory is that taking deep breath causes downward flow of spinal fluid and blood flow in the brain.Edit as suggested by Kristina:Another theory is that the yawning is a defensive reflex of the ears to equalize pressure of the air trapped in our ears to that of outside pressure due to the changes in barometric pressure[5].There are as many theories as there are people.Correct answer is - no one really knows.And it is contagious which is shown to be true by mythbusters[6].Footnotes[1] Why We Yawn[2] Why Do I Yawn?[3] Why Do We Yawn and Is It Contagious?[4] Why do we yawn? (Everyday Mysteries: Fun Science Facts from the Library of Congress)[5] Yawning and its physiological significance[6] Is Yawning Contagious MiniMyth
Why do we 'yawn' when tired?
New research suggests that it doesn't have to do with inadequate oxygen; otherwise, why wouldn't a deep breath through the nose, or pursed lips, suppress the urge to yawn? It's a fascinating little "invention" that our brain made up, actually. Your nose is designed to warm and humidify the air that passes through it. But what if your brain needs a cool little wake-up call? Like splashing cold water on your face when you're sleepy, except for your brain? Here's how it does it: the soft palate (the soft part of the roof of your mouth, in the back) is very thin. It's pretty much the only place that the brain is protected only by tissue and not by bone. So when you open your mouth up really wide, and expose it to room air, your brain gets a little whoosh of cool air. Even if it's really hot out (80 degrees, say), it's cooler than your brain, which is at body temperature of 98 degrees. That cool air reinvigorates your brain. It causes constriction of the blood vessels, which gets the blood moving a little faster. It eliminates that thick, hot, slow feeling you get in your whole body when it's really hot out. During those critical times when you just can't yawn, try opening your lips just a little bit, pulling your tongue away from the roof of your mouth, and taking a deep breath. It looks a little strange, but it takes the urge away and doesn't look as bad as the full-on, jaw-gaping yawn. Taking deep breaths through your nose doesn't do anything. On a similar note, that's why you get brain freeze. The soft palate, that thin little piece of tissue, gets cold which chills your brain right off. Your blood vessels constrict really fast (they think some kind of ice storm is coming into your skull), which is what causes the pain. So that's why it's worse when you drink through a straw: it shoots it right back at the soft palate, instead of having a short chance to warm up as it passes by the tongue and the hard palate.
Why do I yawn when I'm hungry?
It is not necessarily that you are yawning when you are hungry, people yawn when there body needs more oxygen. So perhaps you should go get some fresh air and relax.
Why does yawning make you cry?
Sometimes when you yawn very strong you contort your facial muscles putting enough pressure to squeeze tears form the tear ducts.
Why do we yawn when we are hungry?
Yawning results due to a sudden decrease of oxygen in the blood and lungs. This can occur when we are tired, but it also occurs when our blood sugar level is low. When the level is low, a sudden burst of oxygen will be required to produce energy. This decreases our oxygen levels, causing us to yawn.