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Yawning: It Isn't About Oxygen Anymore

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Biology 103
2003 Second Paper
On Serendip

Yawning: It Isn't About Oxygen Anymore

Abigail Fritz

Have you ever wondered why yawns are contagious; have you ever been in class and seen someone across the room yawn and found yourself following along? Have you ever been reading a book and, upon coming across a yawning character, been moved to stretch out your own face muscles? Most likely these things have happened to almost everyone more times than they can remember. I cannot tell you how many times I have yawned in the process of researching and writing this paper. A friend of mine began to yawn uncontrollably as I discussed my ideas with her.

Yawning is a phenomenon that occurs for most people many times a day, yet it is not one that has been studied extensively by researchers. This is an unfortunate fact because he more I read about yawning and thought about number of situations in which it occurs, the more eager I became to better understand what is behind humans' tendency to yawn.

At first, one might see yawning as a silly phenomenon to spend time studying because, well, it is just what happens when we are tired; but it is more complicated than that. We yawn when we are tired, but also when we wake up, when we are bored, and even simply because we see others doing it. When one delves into the unknown of what causes a yawn, he or she will become intrigued by how mysterious the occurrence is and surprised about how little we known about it. The following will discuss the many theories that have been put forward regarding the phenomenon and its contagious qualities and explore the implications and problems with these various theories.

There exist both theories as to why we yawn and theories as to why yawns are contagious. Let us first look into why we yawn. The theory that has long been thought to explain yawning, and the one that has often used in medical textbooks, is that we yawn due to low oxygen levels in the lungs (1). When we are in a resting state, we make use of a very small percentage of our lungs' capacity and are only using the air sacs, or alveoli, in the bottom of our lungs (1). The alveoli partially collapse when the air sacs stop receiving fresh air, cueing our brains to induce a yawn (1). This theory has been largely cast aside, however, because our lungs do not necessarily detect oxygen levels (8).

The interesting contrast to the low-oxygen theory is that some observations have been made that suggest that fetuses in the womb yawn. Doctors have observed fetal yawning in utero at twenty weeks gestation and noted a 'fetal yawning movement' (7). Mouths opened widely resembling a yawn with qualities quite different from those of a brief moment of swallowing and the mouth remained open for around two minutes (7). These observations do not support the oxygen theory because fetuses in utero do not yet have ventilated lungs (8). Other doctors have responded to these observations in the New England Journal of Medicine saying that, "there is too much of a range of variation in the observations and that there is a discrepancy in the use of the anatomical criterion of retraction of the tongue to characterize the fetal yawn, whereas in yawning adults, the tongue is extended" (7).

One interesting study on the cause of yawning hypothesized that, "contagious yawning occurs as a result of a theory of mind, the ability to infer or empathize with what others want, know, or intend to do. Seeing or hearing about another person yawn may tap a primitive neurological substrate responsible for self-awareness and empathic modeling which produces a corresponding response in oneself" (2). Researchers tested this hypothesis by observing individuals that exhibited schizotypal personality traits. They felt that those traits would inhibit a person's ability to process information about the self and would therefore lower their tendency to yawn contagiously (2). Their lowered ability to identify with another's state of mind would prevent them from 'catching the yawns' as a result of empathizing with someone seen yawning. The researchers' findings were consistent with their hypothesis and could aid in explaining why schizophrenics rarely catch the yawns (3). Another experiment conducted at New York State University's Department of Psychology declared similar findings stating, "We have also shown that individuals who score higher on schizotypal personality traits are less likely to show contagious yawning because of a fundamental impairment of self-processing" (9).

There are evolutionary theories for yawning. Robert Provine, professor of psychology at the University of Maryland Baltimore County, suggests that yawning is about "transitions in the body's biology" (5). This theory might support observations that suggest fetal yawning. Perhaps it aids in maintaining the balance of amniotic fluid. Provine goes on to say that yawning can occur not only when transitioning from a state of alertness to a state of sleepiness, but also from a transition from sleepiness to alertness (5). He makes the point that, "at track and field events, sometimes you'll find participants in the race of their life will be standing around on the sidelines or in the starting block and they may be yawning. Or before a concert, a musician may yawn to prepare for an increasingly energized state" (5). The evolutionary theory behind this is that yawning is a result of synchronizing behavior based on these changing states of alertness (5). The changes in your body that "are brought about by yawning are synchronized in everyone that's doing it" (5). The associate professor of physiology at the Lake Erie College of Osteopathic Medicine suggested a similar theory, stating that, "the contagious nature of yawning is most likely a means of communication within groups of animals, possibly as a means to synchronize behavior; therefore in humans it is most likely vestigial and an evolutionarily ancient mechanism that has lost its significance" (8). Just as our teeth have gotten smaller as we have evolved, so has the significance and meaning of the yawn.

Continuing along the lines of evolution, one might consider the yawn in term of a link to our "furrier days" (6). At that point in human evolution, we would yawn to show our teeth, which is why zoologists speculate animals yawn. According to this theory, when someone near us yawns, our "subconscious Neanderthal responds to the 'aggressive challenge' with an I-have-big-teeth-too-yawn" (6). As the writer of the article that discusses this theory agrees and teases, the 'furry days theory' seems to be a fairly far-fetched argument. It makes sense that animals show their teeth to intimidate other animals, but should we call that a yawn or equate that act with the human act of yawning? It is hard to imagine that we are subconsciously putting forth an "aggressive challenge." Consider throwing the theory of evolution out the window. We cannot be certain that humans have evolved from monkeys. If, in fact, we have not, how might we explain the yawning phenomenon? I would like to suggest two theories that seem to me to bear the most significant and convincing evidence for why we yawn and why yawns are contagious.

There have been so many theories, and just as one of them starts to become convincing, a different discussion presents information that suggests such a theory does not make sense. Despite these discrepancies, we have to begin to make sense of the act somewhere. Yawning is undeniably a contagious phenomenon that I am convinced is more than a result of evolutionary adjustments and that has become an act having little meaning and that is insignificant to our function as humans. The idea of yawning being about transitions in the body's biology is my "first pick" as an explanation for yawning and into which I am inclined to look further. Through some discussions with my friends, it became clear that they not only yawn when they are tired, but many of them also yawn when they wake up in the morning. Further, I have been surprised to find myself yawning on numerous occasions because I was not feeling any hint of being sleepy, but perhaps it occurred at moments when something was happening for which I needed to be more alert than normal, and my body therefore responded with a yawn.

The theory of mind suggestion is my "second pick" and the experiment described earlier carried some very intriguing implications. It was interesting to think about the phenomenon in terms of personality traits that might lessen a person's chance to experience the same phenomenon. The fact that a schizophrenic patient does not 'catch the yawns' as easily as someone without the disease because of their difficulty in identifying with another's state of mind is convincing information in support of the theory of mind concept. Humans are very receptive organisms that respond quickly to the feelings and emotions of the individuals around them. We often find ourselves being very connected to those that we are close to in terms of interpreting moods and finding ourselves saying the same things at the same time or finishing sentences. These human tendencies convince me that a theory of mind that explains yawning is a very likely one. Our capabilities to connect with others on personal, intellectual, and subconscious levels are qualities of the human experience that are very difficult to explain, but that exist nonetheless. These characteristics are what make us such complex organisms.


1) NBC News Health , Theory on why we yawn.

2) Good study on schizotypal patients

3)Nature: Science Update, Links self-awareness and yawning

4)National Library of Medicine, The Neuropharmacology of Yawning

5)NBC News, Yawning and its Contagious Tendencies

6)Island Scene Online, Speaks on why a yawn can be more contagious than the flu

7)Fetal yawning in utero, Addresses observations of fetal yawning at 20 weeks

8)Scientific American, Addresses why we yawn and why yawning is contagious

9)Article in press at, Discusses the impact of schizotypal personality traits



Continuing conversation
(to contribute your own observations/thoughts, post a comment below)

06/26/2005, from a Reader on the Web

do you hav visited my website ? and my laste publication in draft mode : best regards olivier


Additional comments made prior to 2007
The reason I was looking up "yawning" is because it seems that when I am speaking to people, it makes them yawn. It has been happening to me for quite a few years - at least 10 years and has involved many different people. At present it is happening with my supervisor at work. I find it very insulting and makes me uncomfortable, as well the the person yawning. I now try not to speak to her as much as possible. I will tell you I have COPD and still a smoker. Is it possible that I am emmitting high levels of carbon minoxide that may be causing these people to yawn? Or maybe it is just the sound of my voice? Any insight would be appreciated. Thank you ... Addie Ballin, 14 October 2007


Andreas Gabriel's picture


We yawn to prepare upper airways for sleep and other situations where clear and open airways are needed. My sleep apnea is greatly reduced by yawning and imitating yawning before before going to bed.

Contagioness is because we humans throughout history slept together and need to go to sleep together at the same time. There are also many many other behaviors we humans mirror each other. Ovulation, sneezing, nodding...

Champers11's picture

Yawning not fully explained

I don't think any of the theories above fully explain the phenomenon of yawning and the range of physiological and psychological reasons behind it, which I think are numerous. I've previously come across the theory that people will yawn in response to information they have difficulty assimilating, which I think has validity. The reason I looked up yawning today is because I've noticed that I now yawn a lot during therapy sessions when specific topics are discussed with my husband--is it boredom, tiredness or a refusal to engage on the subject? The rate of incidence makes me think it's definitely psychological rather than physiological.

Bettiola's picture

Yawning as Tension Release

One theory of yawning which I have not seen mentioned here is that it is a release of tension. And that's why musicians and athletes often yawn before performing. There is also a theory relating to the chemical make-up of tears. I believe that there is research showing that the chemical makeup of tears caused by sorrow are different from tears caused by cutting an onion. The tears released by sorrow may be releasing toxins in the body resulting from distress. Has anyone made a chemical anlaysis of the tears released by yawning?

Dr. Quack's picture


Yawning is a defense mechanism of our body from abnormalities w/c may or may not need medical treatment caused by different factors such as stress, fatigue, exposure from chemicals, side effect of drugs and can be phsycological in nature. Once the brain detects the abnormalities, it send signal to the nervous system to conduct yawning. If you need further clarication w/ regards to cause and effect of yawning, please feel free to post your question here.

Serendip Visitor's picture

Defence Mechanism

I can see how yawning can be a Defence mechanism. My wife instinctively yawns when I or my daughter go to give her a hug or a kiss - she keeps her arms by her side and yawns a half yawn before she accepts the hug or kiss.

Mary's picture


Always when I am driving I start yawning - non stop. I have discovered that when I start to yawn, I chew gum and the yawning stops. I have no idea why it works but it certainly works for me.

mattocks's picture


I have chewing gum handy in the home and in the car. I nearly always start yawning within in the first 5 minutes of driving, eyes water and the yawning continues until I pop i gun tablet in my mouth, yawning stops.
Happens socially generally after a small meal, looks bad so I pop a gum and problem fixed, chewing gum does not look good but yawning looks worse.
I have a rare heart defect no RCA, and had assumed the yawning was related to tiredness, these yawning attacks can occur anywhere and anytime but once I start driving it is bound to occur every time and 1 gum tablet does the trick.

john's picture


Yes I also have found chewing gum continuously while driving cures the yawn problem which helps road safety probably because the blood circulates through the brain more which means this is a clue to the mystery of why we yawn. Experiments should be done to investigate this would you agree?

Anonymous's picture

uncompleted yawn

Can someone explain why sometimes a yawn 'does not complete'. And you need to keep doing it UNTIL it completes itself?? Of late I have been doing that a lot and don't know the reason for it.

PHYLLIS J. VANCE's picture



Anonymous's picture

The reason I was looking up

The reason I was looking up "yawning" is because it seems that when I am speaking to people, it makes them yawn. It has been happening to me for quite a few years - at least 10 years and has involved many different people. At present it is happening with my supervisor at work. I find it very insulting and makes me uncomfortable, as well the the person yawning. I now try not to speak to her as much as possible. I will tell you I have COPD and still a smoker. Is it possible that I am emmitting high levels of carbon minoxide that may be causing these people to yawn? Or maybe it is just the sound of my voice? Any insight would be appreciated. Thank you ... Addie Ballin, 14 October 2007

Any suggestions for this????

rick1234's picture


I have had the same problem in the last few years, my voice has changed to some kind of mono tone. I think my acid reflux has changed my vocal cords some way and I make people yawn, I cant say a complete sentence, without someone trying to hold back their yawn. Seriously, like a quick hypnotic suggestion. First I thought what I was saying was boring, or I was long winded so I would hardly speak a sentence afraid to make them yawn. But then I realized that even to order coffee at the drive through. The clerk could not keep a simple coffee order straight. Not just one time, I mean every time, (Dumb asses). Tried speaking the order slowly to no avail, different tones of voice seemed to work a little better, without sounding like a complete idiot. No it has nothing to do with being boring, I am far from boring, Don't seem to have this problem when partying (drinking) I'm pretty sure on this. A little louder voice or change of tone maybe the difference. I am positive I could hypnotize a person in 30 seconds if I learned the art. Seriously people loose their concentration of what I am saying within 2 seconds and most of the time I can trigger a yawn before the second verbal sentence is out.

Champers11's picture


What is the topic you are presenting on/discussing? Often people yawn when they are being asked to assimilate information they don't want to hear. Another theory that isn't described above.

Nicholas Hunt's picture


I have also noticed this yawning phenomenon while I'm speaking with someone; and it doesn't matter who it is. It makes no difference whether they're a peer, a manager, or my subordinate. My original thought was the obvious, they're bored. I don't think that's it (always) because sometimes these people seek me out for my opinion - and still yawn. I began thinking it was my vocal tone, or my manner of speech and inflection. Then I thought it was my facial expression; Maybe I looked like I was going to yawn. It happens even during very engaging and complicated exchanges with total engagement of the yawner.

I've started trying to reverse engineer the mechanism a bit. Why do I want to yawn (but stifle it of course) when I'm talking to someone? It's never out of disrespect; Not due to boredom - I usually just get antsy when that happens. The I realized, if it's not a sympathy yawn if course, that it occurred during instances when when I was fully in agreement or completely engaged and in synch with the person's position.

Still pisses me off though.

Max's picture

I would suggest recording

I would suggest recording yourself speak and listening to it to see what you actually sound like. I have to make a conscious effort to improve the sound of my voice and it does make a big difference.

Mercedes Rodriguez's picture



I found this webpage as interested in YAWNING. If you are in touch with researchers interested in yawing please do resend them my email. Thanks.


I myself have also an interest in yawning and I have a different, possibly original idea which I would like to share with other researchers, in order to see if with the help of everyone we can enlighten such a mysterious biological function.

Yawning could be a way of getting rid of volatile substances, either from internal origin such as nitric oxide (?) or from outside origin. The jungle of chemicals that we breath all the time are supposed to be detoxyfied by healthy airways by means of fluids lining the mucosae, the antioxidant enzimes and other measures. However sometimes this function might be faulty and too many volatile chemicals might go deep into the airways and lungs.

A powerful blowing out during the yawning would discharge the airways of volatile chemicals and send them away, cleaning the organism from certain unnecessary, perhaps noxious chemical compounds.

Yawning would not be due to sleepiness, boredom and so on. While we yawn we lose for a moment the awareness of our environment, eyes fill with tears, etc. That is inconvenient for a predator or for a prey. What would happen is that the creature would wait until it was relaxed, (before sleeping, bored, etc) in order to exhale more a powerful yawn more at rest. It would be contagious because it would serve to remind animals that it is good to take a moment of time to clean their organism from unwanted volatile chemicals.

If I am correct it would be most interesting to analyze with precision what gases are exhaled by people and animals during spontaneous yawning (they does not have to be the same, biochemistry is different between species). It would be necessary to avoid obvious "psychological" yawning, those of people who just yawn as a tic.

If you find this an interesting idea I could comment it further but for the moment I prefer not to make this email too long.

Mercedes Rodriguez Escudero

Syn.'s picture


Hello mercedes.

After having read your theory almost year ago I've since noted almost everytime I've yawned that on more then possibly 90% of my yawns were in fact of a low pressure of air flow emmited from my mouth. On most occasions my yawn was merely but a soft breeze.

Also I thought that say your theory of the excretion of volatile substances were in fct true, this should very well mean that smokers would clinically yawn more often then any other person. And from my own personally experiences, smokers don't yawn any more often then any other person. Even a smoker of 50 ciggarettes a day.

This reply is purely speculation. I am in no way trying to just make you feel uneasy about your theory, in fact I thought your theory was rather intriging and it led to me having thought about it for over months haha so kudos to you ;)

DennisNPS's picture

Yawning Theory

I believe I have come up with a fairly solid theory... please tell me what you think.
The human body (in its original shape) was equipped with things that we do not put full use to in our current age. For example the appendix, thousands of years ago when we didnt cook our meals yet, the appendix helped us digest raw meat. Now adays we dont eat raw meat anymore so the use of appendix is not needed anymore. same thing with our widsom teeth, a long time ago they were needed because the jaw was under heavier use. Well I believe that a loong time ago when humans havent developed speech yet. The yawning was like a howling, and just like wolfs we subconciously respond to that howl.

Anonymous's picture

good site! this site is

good site! this site is very imformative..and not just about yawning. its a little boring....i mean...idk the way you formated the information i found myself yawning if u made it look interesting and shorter but dont take anything out id sit and read the whole thing!!!

Anonymous's picture


when people look at me they yawn or explaining something they yawn, talking to them they yawn, even some meters away they yawn, what is that please help it makes me feel unconfortable.

Linda's picture


I noticed people yawn at me too mostly women. I'll be in my car or in a store and I'll feel someone staring at me and when I look sure enough someone is not only staring but yawining a big wide yawn,it's creepy.

Anonymous's picture


when peopple see me they yawn, when i talk to them they yawn to/ what must i do to stop this.

sometimes i think maybe is the devil who is making people to yawn. please let me know, if is normal or a desease.

Dilini's picture

I have also noted that i

I have also noted that i yawned several times within 5 minutes. I dont know why it happend. I want to know is this a desease?

Pls let me know it.

Leon's picture

Re: Ms Ballin's experience

I have also noted the same, at times, with people I am trying to engage in tete a tete. It usually happens when discussing subject matter whose content is theoretical or speculative and seems to require some familiarity with the subject or particular interest in me and my ideas, or openness to new and unfamiliar ideas that offer a different approach and view of life experience or thought. I have said in myself that it is not my intention to merely hear myself talk, or to criticize myself for not being a "dynamic speaker" or communicator, but have thought that I, myself, have not had the fullness of being to communicate well enough or that I may not have fully considered the person to whom I may be speaking or that I might have wrongly concluded my opinion of whom I was speaking, or that I was not prepared to communicate certain ideas with the dynamism that comes from personal experience and understanding of the subject at hand, which might allow some common experience, thoughts, opinions or conclusions to be mutually recognized. I have seen people's eyes "glaze over" and heard them yawn unconciously, as well as, look as if they were being hypnotized. I have then felt suddenly alone. I try to release feelings of insult or being treated indifferently. I am aware that listening receptively is not the same as being made passive by "long-windedness, words or ideas which do not afford debate, argument, or an opportunity for mutual exchange. I also know that saying too much and for too long often does not lend itself to the opportunity of the other to choose what to assimilate among the "banquet of ideas" presented, very much like feeling full when there is too much on one's plate. I have also had a friend tell me that I often say things about which it seems no more can be said. "Pushy" perhaps? I realize some of us wax philosophical more readily or habitually and I am trying to sort my way to the wisdom preceeding this. And since I did not or could make this response brief, it has probably gone on too long :); I, I ,I and I..., end.

Ron's picture

I can relate, but tend to

I can relate, but tend to feel that the folks who yawn during my topic of converation are also on my payroll, and are usually listening to highly intellectual subject matter.They simply may need more oxygen to the brain to catch up to my level of thought.;D.

Leon's picture

Yawning by contagion

Hello Abigail, I came across your article while surfing autism and watching "Larry King Live", which had "famous" people who had children with that diagnosis. I became aware of the idea of aspects of yawning through the work of P.D. Ouspensky in his book "In Search of the Miraculous", published in 1949. Immediately after becoming aware of these ideas I was able not to yawn, more often than not, upon observing it in someone else. My own conclusion, surely anecdotal, was that there was a moment of choice in which to respond to those ocassions with awarness and willing intention and not experience the usual effect whose cause seemed to be, at least on the surface, the viewing of someone else yawning. I also noticed that if the underlying altering of course or "tonic" of awareness, if you will, brought to bear within the cycle of cause and effect was not strongly re-enforced or maintained for some small but significant amount of time that I would eventually yawn. I also have noted that if the awarness is not complete enough (for me) to recall the "window" or moment of opening which allows willing choice in a "timely" way and meeting the, let's say, wave of reflex, I was likely to yawn deeply accompanied by strectching of facial muscles and body, from toe to head, or in a reduced and abbreviated manner, as if, half remembering that I might have resisted the instinctive reflex. Hope this is useful. Leon