why is yawning contageous?
399024
I swear this question has been asked 20 times in the last 3 days. You can't tell me you don't know how to Google for this or check other peoples answers.
532727
A yawn is a reflex of deep inhalation and exhalation associated with being tired, with a need to sleep, or from boredom.\n\nYawning is a powerful non-verbal message with several possible meanings, depending on the circumstances. It is also claimed to help increase the state of alertness of a person.\n\nCauses of yawning:\n1. An indication of tiredness, stress, over-work or boredom. \n2. An action indicating psychological decompression after a state of high alert. \n3. A means of expressing powerful emotions like anger, rejection or apathy. \n4. A sign that one is not breathing deeply, and not receiving enough oxygen through the body. \n5. A yawn can express strong anti-social messages, and so in some cultures people try to mute or mask them by placing a concealing hand over the yawning mouth.\n\nA long-standing hypothesis is that yawning is caused by an excess of carbon dioxide and lack of oxygen in the blood. The brain stem detects this and triggers the yawn reflex. The mouth stretches wide and the lungs inhale deeply, bringing oxygen into the lungs and hence to the bloodstream
41848
I have a theory on this to share.\nMay be yawning is not a chain reaction at all.\nIts just our reaction to the state of things, outside as well as inside our body.\nFor instance, we feel sleepy when our brains are tired or refuse to process. Result is that we all yawn when after a tired game, after a boring speech.\nMay be even when there is lack of sufficient oxygen.\nWe all have different reaction times though. Thats probably the reason why its being mistaken to be a chain reaction.
363390
The yawn reflex is often described as contagious: if one person yawns, this will cause another person to "sympathetically" yawn. The reasons for this are unclear; however, recent research suggests that yawning might be a herd instinct. Other theories suggest that the yawn serves to synchronize mood behavior among gregarious animals, similar to the howling of the wolf pack during a full moon. It signals tiredness to other members of the group in order to synchronize sleeping patterns and periods of activity. It can serve as a warning in displaying large, canine teeth, thus proclaiming, "don't attack while I am sleeping..." The contagion of yawning is interspecific (i.e., try yawning in front of your dog). Ironically, yawning in public is generally regarded as impolite in the West, but came into fashion in polite French society for a brief period in the late 18th century. Oddly, sometimes sympathetic yawning may be caused by simply looking at a picture of a person or animal yawning, or even seeing the word "yawn".\n\nAdelie Penguins employ yawning as part of their courtship ritual. Penguin couples face off and the males engage in what is described as an "ecstatic display," their beaks open wide and their faces pointed skyward.
65932
From straightdope:\n\n"nobody really knows. Fact is, we don't know why people yawn, period.\n\nIt was long believed you yawned when there was too much carbon dioxide and not enough oxygen in your blood. A part of your brain called the brain stem detected this and triggered the yawn reflex. Your mouth stretched wide and you inhaled deeply, shooting a jolt of oxygen into the lungs and thence to the bloodstream.\n\nSubsequently, you exhaled a lot of CO2. Often you'd stretch while yawning, which seemed to temporarily improve circulation. You yawned and stretched a lot more when you got tired because your breathing slowed down.\n\nOr so people thought. In recent years, though, a few radicals have said the preceding is all malarkey. Who knows, they say, maybe we yawn because it's too warm in the room.\n\nCecil isn't about to settle the issue here, and he doesn't need to. We merely observe that whatever yawn-inducing conditions prevail for you also apply to your friends.\n\nIf you're out late in some crowded dive, you're probably all tired, all warm under the collar, and all breathing the same stale air. You're probably all on the verge of a yawn, too, and the power of suggestion from seeing one person do it is enough to push everybody else over the edge.\n\nAdults rarely catch a case of the yawns from a child or animal, which tends to corroborate this idea.\n\nChildren usually have different sleep schedules and respiration rates from adults, so you would expect them to yawn at different times. Animals, on the other hand, often yawn not for physiological reasons but as a display of hostility, to which humans are evidently unresponsive."
337700
From a lack of oxygen. Yawning is when your blood circulation slows down i.e at high altitude average people yawns at least 7 times per minutes.\n\nAlso a sign that adrenaline is slowing down and if inactive, the body will shut down.  Involuntary but necessary, seeing people doing so reminds us that the body needs it...
414151
What's behind this mysterious epidemic of yawning? First, let's look at what a yawn is. Yawning is an involuntary action that causes us to open our mouths wide and breathe in deeply. We know it's involuntary because we do it even before we are born. Research shows that 11-week-old fetuses yawn. \n\nThere are many parts of the body that are in action when you yawn. First, your mouth opens and jaw drops, allowing as much air to be taken in as possible. When you inhale, the air taken in is filling your lungs. Your abdominal muscles flex and your diaphragm is pushed down. The air you breath in expands the lungs to capacity and then some of the air is blown back out. \n\nWhile the dictionary tells us that yawning is caused by being fatigued, drowsy or bored, scientists are discovering that there is more to yawning than what most people think. Not much is known about why we yawn or if it serves any useful function, and very little research has been done on the subject. However, there are several theories about why we yawn. Here are the three most common theories: \n\n\nThe Physiological Theory -- Our bodies induce yawning to drawn in more oxygen or remove a build-up of carbon dioxide. This theory helps explain why we yawn in groups. Larger groups produce more carbon dioxide, which means our bodies would act to draw in more oxygen and get rid of the excess carbon dioxide. However, if our bodies make us yawn to drawn in needed oxygen, wouldn't we yawn during exercise? Robert Provine, a psychologist at the University of Maryland, Baltimore County, and a leading expert on yawning, has tested this theory. Giving people additional oxygen didn't decrease yawning and decreasing the amount of carbon dioxide in a subject's environment also didn't prevent yawning. \nThe Evolution Theory -- Some think that yawning is something that began with our ancestors, who used yawning to show their teeth and intimidate others. An offshoot of this theory is the idea that yawning developed from early man as a signal for us to change activities. \nThe Boredom Theory -- In the dictionary, yawning is said to be caused by boredom, fatigue or drowsiness. Although we do tend to yawn when bored or tired, this theory doesn't explain why Olympic athletes yawn right before they compete in their event. It's doubtful that they are bored with the world watching them. \nThe simple truth is that even though humans have been yawning for possibly as long as they have existed, we have no clue as to why we do it. Maybe it serves some healthful purpose. It does cause us to draw in more air and our hearts to race faster than normal, but so does exercise. There's still much we don't understand about our own brains, so maybe yawning is triggered by some area of the brain we have yet to discover. We do know that yawning is not limited to man. Cats, dogs, even fish yawn, which leads us back to the idea that yawning is some form of communication. \n\nHave we provoked a yawn out of you yet? If we have, hopefully it's not out of boredom, but by the power of suggestion.
220911
Why is yawning infectious? \n\nGemma Martin, London UK\nWhen you yawn, you equalise the pressure in your middle ear. This causes a small, localised pressure change around you, which affects others in the vicinity - and therefore they have to yawn to equalise the pressure in their own middle ears. \n\nJoe Lambert, Norwich, England\nIt's a left over mechanism from our days as troupe creatures. Infectious yawning meant that we slept togther as a group when the most tired required to sleep. \n\nPeter Brooke, By Kinmuck Scotland\nIn 1990,in Guardian Notes and Queries vol.1, an answer was that it was part of a mechanism to "synchronise wake/sleep cycles" among people in a social group, and that yawning is poorly understood. I don't know if progress has been made since then. \n\nivor solomons, norwich england\nThis applies only to group/troupe animals. It supplies a method for the most sleepy to forcefully communicate their need for rest and thus ensures that the group rests/sleeps together. \n\nPeter Brooke, By Kinmuck, UK\nYawning is essentially a reflexive method of increasing oxygen intake. Oxygen intake in this manner is primarily used as a means to stay alert. When we observe others yawn it triggers a warning to ourselves that we are in a situation where we need to be alert, hence the infectious desire to yawn yourself. \n\nAndy Preston, Otley, UK\nIf you accept the theory that yawning is related to breathing, as a means to either redistribute lung surfactant or to temporarily increase air intake, it may be that watching someone yawn triggers a subconcious concern about one's own ability to breathe, hence mimicking the yawn. Alternatively, it may be a throwback to primate warning signs, which involve displaying of teeth when threatened. The common response to this is a reciprocal baring of teeth. \n\nBrendan O'Sullivan, Birmingham, UK\nThere is no one answer to this question, other than unsatisfying ones like "because we evolved that way". Or more accurately, some species in our distant past evolved that way (if you yawn at a dog, it will often yawn back, and chimpanzees also exhibit contageous yawning). Yawning might help communicate to other members of a group that it's time for everyone to settle down for a snooze, but (like laughing and frowning), it's hard to explain why this particular behaviour should represent this meaning. \n\nAllan Dean, Wimbledon \nI've heard it's because when the alpha male in the group of apes (which turned into us)had checked everything out and knew it was safe to sleep he would yawn to other apes, as a message that all was safe, and they in turn would yawn the message through the group, so it's instinctive. \n\nDonna Thomas, Bristol, UK\nIt's because you're afraid that other people are stealing your air \n\nJimmy, Ceredigion, Wales\nSteven Platek, a professor of cognitive neuroscience at Drexel University in Phildelphia, has carried out research correlating the "echoing" of yawns with the empathetic response of the individual. In other words it is a kind of social response, and those deficient in the ability to make emotional bonds (schizotypal individuals) are less likely to yawn back. \n\nTony Dunlop, Zeal Monachorum, England
1159613
Ahhh... the age old question. lol\n\nThere are a number of theories. One is that when someone yawns, they take oxygen out of the air, and we need the oxygen so we yawn to get the oxygen we need. I'm not sure about that one. I think its just a joke.\n\nA more likely theory is that it relates back to the herd instinct. You know, monkey see, monkey do.
829322
1- During a yawn, there is a slight increase in pressure inside the skull (likely caused by slight increases in the amount of oxygen taken in during a deep yawn). This causes the cerebrospinal fluid (CSF), the fluid that surrounds the brain and flows through the brain's ventricle system, to be forced out faster than normal. That fluid enters the lachrymal (tear) system. That increase in fluid pushes out the tears.\n\n2 - the more simplistic reason may be that when you yawn you scrunch up a bunch of facial muscles. That causes the tear glands and ducts to be squished, forcing out some tears.\n\n\nTalks about yawning as well:\nhttp://en.wikipedia.org/wiki/Yawn#Causes_of_yawning
775112
It's a sympathetic reaction that makes them contagious.  A yawn happens when your body is not receiving enough oxygen.  You yawn when someone else yawns because of this sympathetic reaction.  Mythbusters did an experiment on this topic on one of their shows.
632459
Causes of yawning\n1.An indication of tiredness, stress, over-work or boredom. \n2.An action indicating psychological decompression after a state of high alert. \n3.A means of expressing powerful emotions like anger, rejection or apathy. \n4.A sign that one is not breathing deeply, and not receiving enough oxygen through the body. \nA yawn can express strong anti-social messages, and so in some cultures people try to mute or mask them by placing a concealing hand over the yawning mouth.\n\nA long-standing hypothesis is that yawning is caused by an excess of carbon dioxide and lack of oxygen in the blood. The brain stem detects this and triggers the yawn reflex. The mouth stretches wide and the lungs inhale deeply, bringing oxygen into the lungs and hence to the bloodstream. It is almost certain however, that this hypothesis is not correct. One study documented that this effect does not exist ("Yawning" by Robert R. Provine, pages 532-539, American Scientist, November-December 2005, Vol 93, No. 6). A more recent hypothesis is that yawning is used for regulation of body temperature. Another hypothesis is that yawns are caused by the same chemicals (neurotransmitters) in the brain that affect emotions, mood, appetite and other phenomena. These chemicals include serotonin, dopamine, glutamic acid and nitric oxide. As more of these compounds are activated in the brain, the frequency of yawning increases. Conversely, a greater presence in the brain of opiate neurotransmitters such as endorphins, reduces the frequency of yawning. Patients taking the serotonin reuptake inhibitor Paxil (Paroxetine HCl) have been observed yawning abnormally often.\n\nAnother theory is that yawning is similar to stretching. Yawning, like stretching, increases blood pressure and heart rate while also flexing many muscles and joints. Some have observed that if you try to stifle or prevent a yawn by clenching your jaws shut, the yawn is unsatisfying. As such, the stretching of jaw and face muscles seems to be necessary for a good yawn.\n\nThe yawn reflex is often described as contagious: if one person yawns, this will cause another person to "sympathetically" yawn.[2] The reasons for this are unclear; however, recent research suggests that yawning might be a herd instinct.[3] Other theories suggest that the yawn serves to synchronize mood behavior among gregarious animals, similar to the howling of the wolf pack during a full moon. It signals tiredness to other members of the group in order to synchronize sleeping patterns and periods of activity. It can serve as a warning in displaying large, canine teeth, thus proclaiming, "don't attack while I am sleeping..." The contagion of yawning is interspecific (i.e., try yawning in front of your dog). Yawning in public is generally regarded as impolite in the West, but came into fashion in polite French society for a brief period in the late 18th century. Oddly, sometimes sympathetic yawning may be caused by simply looking at a picture of a person or animal yawning, or even seeing the word "yawn".\n\nAdelie Penguins employ yawning as part of their courtship ritual. Penguin couples face off and the males engage in what is described as an "ecstatic display," their beaks open wide and their faces pointed skyward.
361765
Not really sure---but just seeing the word yawn made me yawn--Thanks alot---yawns again---wonders about yawns--yawns again-- http://en.wikipedia.org/wiki/Yawn Why are yawns contagious? Getting kind of tired-- http://www.straightdope.com/classics/a2_309.html-- Why do we yawn? http://faculty.washington.edu/chudler/yawning.html A yawn reasearcher? http://psychology.drexel.edu/ECNL/  Huh? Sorry must be groggy--Pictures of animals yawning --Oh No-- yawning out of control-- http://www.animalyawns.com/ all this reading about yawning ---YAWNS deeply--- I'm getting so sleepy ---  It's hard to keep my eyes open--z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z
1051186
When a person yawns it is usually due to the lack of oxygen to the brain. When we see a person yawning our brain interprets  it as low level of oxygen in the air.As a result we yawn.
680125
Here's a theory. Yawning can be caused by lack of oxygen, and if a bunch of people are in the same room which is poorly ventilated (no windows open, no air conditioning, or it's a stiflingly hot room) they could all yawn because of this, as they are all in the same place.\n\nEither that or they are all tired! :D
811887
its so funny i read your question and it made me yawn and made me wonder so i looked it up for ya\n\n\n\nThe yawn reflex is often described as contagious: if one person yawns, this will cause another person to "sympathetically" yawn.[3] The proximate cause for contagious yawning may lie with mirror neurons, i.e. neurons in the frontal cortex of certain vertebrates, which upon being exposed to a stimulus from conspecific (same species) and occasionally interspecific organisms, activates the same regions in the brain[4]. Mirror neurons have been proposed as a driving force for Imitation which lies at the root of much human learning, e.g. language acquisition. Yawning may be an offshoot of the same imitative impulse. At a distal level (in terms of evolutionary advantage), yawning might be a herd instinct.[5] Other theories suggest that the yawn serves to synchronize mood behavior among gregarious animals, similar to the howling of the wolf pack during a full moon. It signals tiredness to other members of the group in order to synchronize sleeping patterns and periods of activity. It can serve as a warning in displaying large, canine teeth. This phenomenon has been observed among various primates. The threat gesture is a way of maintaining order in the primates' social structure. The contagion of yawning is interspecific, for example a human yawning in front of a pet dog can incite the dog to yawn as well. Oddly, sometimes sympathetic yawning may be caused by simply looking at a picture of a person or animal yawning, or even seeing the word yawn.
75237
I'm a registered sleep technologist.  There is no known cause to yawning. It is still a mystery. There are many, many theories, but none proven, thus far.