Why do people yawn??????
85551
I think this deserves to be a featured question.  Here are a few theories and a link below:\n\nEverybody yawns - from unborn babies to the oldest great-grandparent. Animals do it, too. But why, exactly, do people and animals yawn? No one knows for sure. But there are many theories (ideas) about why people yawn. \n\nOne is that when we are bored or tired, we just don't breathe as deeply as we usually do. 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.\n\nYawning, 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. Hmmm. Now what?\n\nAnother theory is that yawning stretches the lungs and lung tissue. Stretching and yawning may be a way to flex muscles and joints, increase heart rate, and feel more awake.\n\nOther people believe that yawning is a protective reflex to redistribute the oil-like substance called surfactant (say: sur-fak-tunt) that helps keep lungs lubricated inside and keeps them from collapsing. So, if we didn't yawn, according to this theory, taking a deep breath would become harder and harder - and that would not be good!\n\nBut there is one idea about yawning that everyone knows to be true. It seems contagious. If you yawn in class, you'll probably notice a few other people will start yawning, too. Even thinking about yawning can get you yawning. How many times have you yawned while reading this article? We hope not many!
15767
People sometimes yawn when they are bored.  This reminds others that they too are bored.  Have you ever seen someone on a roller coaster yawn?  Fortunately you have asked an interesting question, otherwise I would likely be forced to yawn <G>.
55666
I saw something on this before..it said that if you yawn when other people yawn..your a sympathetic person.  In my observing this..I've noticed it's kind of true..particularly..there is a guy that I work with who NEVER yawns when he is around other people who are yawning.  He is not a very sympathetic person at all about anything..kind of rude..or short..I don't know..not very people friendly.  However my friend and I at work are very sympathetic..and we always yawn at the other's yawn! :)
607567
Urge to yawn on seeing someone else yawn is called reflex yawning. When you see someone else yawn, it sends a message across your brain that you also need more oxygen and as a response your open your mouth wide in an attempt to get in more air and your lungs expand (i.e you yawn).
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
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."
967357
The answer is, no one really knows why yawning is "contagious". Or why we yawn at all. One popular explanation is that yawning allows you to get rid of too much carbon dioxide in your system and increase your oxygen supply. This was disproved by Dr. Robert Provine and his research team in 1987.\n\nNow scientists are wondering if yawning is from our deep past -- part of our evolutionary history. Did a yawn signal to the group that it was time for everyone to retire to the trees and snooze? Did a yawn signal that we were all feeling cozy and warm about each other? Did a yawn signal something more like, "Gee, I know how you're feeling, I feel that way too."\n\nBetween 40 and 60 percent of the population seems to find yawning contagious. Researchers at the State University of New York conducted a series of yawning experiments. They determined that being self-aware (the ability to recognize oneself) and having the ability to see things from someone else's viewpoint means a person is more likely to find yawning contagious.\n\nNow you're thinking, what humans are not self-aware? Schizophrenics sometimes have trouble with self-recognition so they will not find yawning contagious. Babies won't yawn contagiously until they're more than a year old.\n\nSome birds and reptiles yawn. Most mammals yawn. My dog yawns, but that doesn't make me yawn -- I obviously cannot put myself in her paw prints. (But who can empathize with a creature that sleeps all day, then when she does bother to get up and join you on a walk, suddenly bolts after a squirrel and nearly tears your arm out of your socket? I have no idea what's going on in that dog's mind.)\n\nChimpanzees yawn too, and in fact, if they watch other chimps yawn, they're more likely to yawn too.\n\nSo, I guess the real answer is: who knows?
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...
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
415659
oh my god theres an invasion of yawning questions
510901
Dr. Barry Make, a pulmonologist at National Jewish Medical and Research Center in Denver, says the answer is not because we are tired or bored — although that’s the common perception. Read on for his explanation.\n\nThe most plausible explanation, and the one that is taught in medical school, is that we yawn because oxygen levels in our lungs are low.\n\nTHE TRUTH IS that we don’t completely understand why people, or animals for that matter, yawn. It’s widely assumed that yawning occurs because we are tired or bored or because we see someone else doing it, but there isn’t any hard evidence to support these beliefs.\n\nThe most plausible explanation, and the one that is taught in medical school, is that we yawn because oxygen levels in our lungs are low. Studies have shown that during normal, at-rest breathing, we don’t use anywhere near our lung capacity; for the most part, we just use the air sacs at the bottom of the lungs. If the air sacs, called alveoli, don’t get fresh air, they partially collapse and the lungs stiffen a bit. As a result, it’s believed, our brain prompts the body to either sigh or take a yawn to get more air into the lungs.\n\nBut certain aspects of yawning remain even more mysterious. Fetuses, for instances, have been observed yawning in the womb, yet it’s known that they don’t take oxygen in through their lungs. And yawning seems to be a symptom of multiple sclerosis and other medical conditions, for reasons unclear.\n\nAnother puzzling phenomenon is that some male animals, men included, yawn in association with penile erection (although it’s presumptuous to assume they’re bored with their sex lives).\n\nNext time you're in a meeting, try this little experiment: Take a big yawn, cover your mouth out of courtesy, and watch and see how many people yawn. There's a good chance that you'll set off a chain reaction of yawns. Before you finish reading this question of the day, it's likely that you will yawn at least once. Don't misunderstand, we aren't intending to bore you, but just reading about yawning will make you yawn, just as seeing or hearing someone else yawn makes us yawn. \n\nInteresting Yawning Facts\n•The average yawn lasts about six seconds. \n•Your heart rate can rise as much as 30 percent during a yawn. \n•55 percent of people will yawn within five minutes of seeing someone else yawn. \n•Blind people yawn more after hearing an audio tape of people yawning. \n•Reading about yawning will make you yawn. \n•Olympic athletes often yawn before competition. \n\nWhat'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. \n\nHere are the three most common theories: \n•The 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. Howeve
537048
Because according to psychology, they are sympathetic responses.  Its funny that in a test, people who didn't yawn after seeing others yawn were found to be anti-social.
337591
because yawns are catching and a yawn is when you are tired and need a hugeee gulp of air so of course if someone in your group has yawned and inhaled alll the air then you nearly suffocate cause you've got no air so you have to yawn to try get some air before you collapse. so blame you friends for snatching the air from your lungs making you yawn !!!!!!!!!!!!!!!!!!!!
217186
In humans, and probably in all those organisms that yawn, yawning is caused by a lack of oxygen. When we are tired, we breathe less often as well as less deeply, so our bodies have evolved a way to fix that problem: forced deep breathe.
467214
Yawns are one of the brain's ways of getting oxygen and fighting fatigue. If someone yawns in response to your yawn it's because they are feeling the same fatigue you are.
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.
329034
We yawn because of a lack of Oxygen. Think about it: when you yawn more air comes in and sometimes after a yawn you feel rejuvenated for a little while. But this is contagious because if you yawn you are probably in an Oxygen-deprived environment and everyone around you is going through the same lack of Oxygen. And yawning is related to sleep because when you're asleep you're barely doing more than breathing, beating your heart and dreaming which doesn't take up much oxygen but you still get the same amount of oxygen as you would awake in the same room so there's more oxygen to relax your brain and mind and everything else that might be tired.