There are several explanations for why we yawn. Perhaps you have already noticed that you often yawn as a reaction to other people yawning. Also, when you talk or read about yawning, you will most likely experience an increased urge to yawn.

Why do we yawn?

A lack of oxygen in the body used to be a common explanation for why do we yawn. The reason for this is that, when you yawn, the body absorbs more oxygen. But this theory has been questioned. This is because foetuses also yawn but they do not inhale oxygen through their lungs. Therefore, it is less likely that you yawn as result of lack of oxygen in you body.

Another explanation is that you yawn in order to stretch the jaw and face muscles. Just as it is important to stretch in the morning to get your body going, a yawn helps activate your face muscles.

Do you find yourself yawning even though you are not tired?

A yawn usually lasts 6 seconds. But you do not only yawn because you are tired. If your brain doesn't get stimulated, you start to get bored. This lowers the temperature in your brain, and this can result in a greater urge to yawn.

Is there a correlation between migraines and yawning?

If you suffer from migraines you will probably have a greater tendency to yawn. During a migraine attack, an accumulation of blood gathers in the brain, which also has a cooling effect on your brain.

Why does the brain get cooled down when you yawn?

One of the most recent theories states that you yawn to cool down your brain. When you yawn, you boost your heart rate and circulation, and this helps to keep your brain cooled. This theory has been supported by a study which establishes that people yawn less during the winter than in the summer. Hence, as the temperature rises, you will automatically have a tendency to yawn more.

What is the explanation for yawning being contagious?

A smile is contagious, so is a yawn. You have probably caught yourself yawning as a result of seeing other people yawn. One of the explanations relates to people’s primeval instinct where the ‘herd’ needed to have the same circadian rhythm. Another explanation is that yawning together with other people is an expression of empathy.

In this case, it is also an interesting fact that who you “get infected by” varies. If you are together with your family, friends or colleagues, the likelihood of yawning increases than if a stranger yawns in your presence. Furthermore, children under the age of 6 are less likely to be “infected by a yawn” than adults. This is down to children’s lack of ability to feel empathy, which they do not learn until later in life.