# Do You Know Why We Yawn and What It Reveals About Us Yawning is one of the most mysterious and fa
Yawning is one of those everyday bodily functions that most people never stop to think about. It simply happens – in the middle of a boring meeting, while reading a book before bed, or first thing in the morning when stretching under the covers. And yet yawning is one of the most mysterious and least understood reflexes of the human body. Scientists have been studying it for decades and still don't have a complete answer to what seems like a simple question: why do we yawn at all?
The most widespread popular belief is that we yawn because we lack oxygen. However, this theory was scientifically debunked several decades ago. Research has shown that neither elevated levels of carbon dioxide in the blood nor reduced oxygen levels reliably trigger yawning. If it were purely about ventilating the lungs, simply breathing more deeply would suffice – and yet the body reaches for this complex, whole-body reflex that simultaneously engages the jaw, neck, chest, and limbs.
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What actually happens in the body during a yawn
Modern neuroscience has come up with a far more interesting explanation. According to the currently most widely accepted theory, yawning primarily serves brain thermoregulation. Professor Andrew Gallup of SUNY Polytechnic Institute, who has long dedicated himself to studying yawning, has published research suggesting that yawning helps cool the brain at moments when its temperature rises – for example, during the transition between sleep and wakefulness or during mental fatigue. The deep breath that accompanies a yawn draws cooler air into the nose and mouth, which then cools the blood vessels supplying the brain. It is essentially a natural cooling system.
This would also explain why people yawn most frequently in the morning after waking and in the evening before falling asleep. These are precisely the moments when the brain shifts its operating mode and its temperature fluctuates. Interestingly, a similar pattern has been observed in other animals – fish, reptiles, birds, and mammals all yawn. Yawning is therefore not the exclusive domain of tired office workers, but an evolutionarily ancient mechanism that has survived millions of years.
Beyond thermoregulation, other hypotheses exist as well. Some scientists believe that yawning aids brain activation and increased alertness by stimulating the nervous system. Others point out that yawning releases tension in the jaw and neck muscles, functioning as a kind of physical "reset." There is likely no single reason – yawning is a complex reflex that serves several functions simultaneously depending on the context.
The connection between yawning and the ears is also fascinating. Many people have noticed that yawning produces a characteristic "pop" or a temporary improvement in hearing. This is caused by the opening of the Eustachian tube, which equalises pressure between the middle ear and the surrounding environment. This is precisely why doctors recommend yawning or swallowing during aeroplane takeoff and landing – it is a natural way to equalise ear pressure.
Yawning is also a deeply social phenomenon, and this is where things become truly interesting. Almost everyone has experienced a situation where someone in the room yawns and, before long, everyone else does too. It can even be enough to merely read about yawning – and one feels the urge to yawn oneself. (How is the reader doing right now?) This contagiousness of yawning is neither coincidence nor a lack of willpower, but a sophisticated neurological and social mechanism.
Contagious yawning and what it reveals about empathy
Research shows that contagious yawning is closely linked to empathy and social bonds. Studies published in the journal PLOS ONE have demonstrated that people who score higher on empathy tests are also more susceptible to contagious yawning. Children under four years of age, individuals with autism, and people with damage to the prefrontal cortex – the brain region associated with social perception – tend to resist contagious yawning more than others.
The mechanism behind this phenomenon is called echopraxia – the unconscious tendency to imitate the movements and gestures of others. This is the same principle behind people unconsciously mirroring the facial expressions of their counterpart or adopting their posture. In this sense, yawning is a form of non-verbal communication that strengthens the social cohesion of a group. As American evolutionary anthropologist Robin Dunbar puts it: "Social bonds are as important for human survival as food and shelter." Contagious yawning may be one of the tools the brain uses to build and maintain them.
Interestingly, contagious yawning has been observed in chimpanzees, dogs, and parrots as well – that is, in animals capable of social learning and possessing some degree of empathy. Dogs, for example, yawn contagiously more in response to their owner's yawn than to a stranger's, suggesting that this effect is genuinely tied to social closeness and trust.
Consider a concrete real-life example: Jana works in an open-plan office and is trying to focus on a report after lunch. The colleague across from her yawns – and Jana, without even realising it, yawns shortly afterwards. Then another colleague yawns. Within five minutes, four people have yawned in succession. Jana then feels guilty, as though she is signalling that she finds the work boring. In reality, however, her brain was simply responding to a social cue while simultaneously trying to maintain optimal temperature and alertness. Nothing more, nothing less.
Yawning also has a relationship with stress and anxiety. Chronic or excessive yawning – that is, yawning that recurs even without obvious fatigue or boredom – can be a sign of heightened nervous system activation. Some athletes yawn before an important performance, actors before stepping on stage, students before an exam. Research suggests that in these situations the brain uses yawning as a way to regulate arousal and prepare the body for performance. It is paradoxical: yawning, which we associate with boredom and laziness, may in fact be an expression of intense mental preparation.
On the other hand, there are situations where excessive yawning signals a health problem. If a person yawns unusually frequently despite getting enough sleep and without any apparent cause, it may be a symptom of various conditions – ranging from sleep apnoea to migraines and neurological disorders, or side effects of certain medications, particularly antidepressants from the SSRI group. According to the Mayo Clinic, excessive yawning that persists over a longer period should be discussed with a doctor, especially if it is accompanied by other symptoms such as headaches, dizziness, or marked fatigue.
Yawning also indirectly reflects sleep quality and overall lifestyle. People who sleep too little or irregularly suffer from chronic fatigue and yawn significantly more. The same applies to people with sedentary lifestyles who spend most of their day in front of a screen without movement or fresh air. In such cases, the brain repeatedly reaches for the yawning reflex as an emergency measure to maintain alertness – but it is merely a patch, not a solution. Regular exercise, sufficient sleep, and time spent in nature are far more effective ways of giving the body and brain what they truly need.
Modern yawning research is also moving into the fields of sports science and cognitive psychology. Studies tracking professional athletes have found that deliberate yawning before performance can improve concentration and reduce nervousness, and some coaches therefore recommend it as part of a pre-competition routine. Similarly, in meditative and breathing practices such as yoga or pranayama, yawning is regarded as a natural sign of nervous system relaxation – if a person yawns during meditation, it is often welcomed as evidence that the body is truly beginning to release tension.
It is also interesting to observe cultural differences in how yawning is perceived. In many cultures, including Czech culture, yawning in public is considered impolite, and people instinctively cover their mouths. This habit has historical roots – in some traditions it was believed that evil spirits could enter the body through an open mouth, or that the soul might escape. Today we know better, but the social reflex of covering one's mouth persists. Yet from a purely biological standpoint, yawning is just as natural a bodily expression as breathing or blinking – the body is doing exactly what it is supposed to do.
The whole story of yawning is, in a way, a metaphor for how little we understand things we take for granted. Every day we yawn an average of five to ten times without pausing to reflect on it. And yet in that brief moment when the jaw opens, the eyes close, and the entire body stretches for an instant, a complex private choreography of the brain, nervous system, and evolution is playing out. Yawning is not a weakness or an act of rudeness – it is quiet evidence that the body is constantly working, regulating itself, and seeking balance. And sometimes, in doing so, it is also telling us that it might be time to rest a little, turn off the screen, and allow ourselves a calm, restful sleep.
