Is yawning a result of oxygen deprivation in the brain?

You wake up from the bed and yawn. You yawn when you fall asleep. After a feast, when your stomach is full, you yawn. After a tiresome day, you yawn. You also tend to yawn when you see, hear, or think of someone

yawning

. But what exactly is yawning?
Yawning is a reflexive action characterized by a deep inhalation by opening the mouth, followed by a short exhalation. It is an involuntary process, that we all encounter once in a while. Though the exact cause of yawning is still not fully understood, it is often triggered by sleepiness or fatigue.

What is yawning?

Yawning is an involuntary reflex where you open your mouth with maximal widening of the jaw, with a long and deep inhalation, through the mouth and nose, and then quickly breathe out. This usually lasts about 4-7 seconds. Though we often associate yawning with tiredness, it begins even before we are born. A fetus yawns in the womb, as early as the 11th week of pregnancy. Studies suggest that yawning in the womb is an indicator of a baby’s health. Yawning is also quite contagious. We all tend to yawn when we see, hear, or sometimes even when we think about it.

Do we yawn, because of oxygen deprivation in the brain?

You must have often heard that the reason behind yawning is oxygen deficiency. However, it is quite a popular misconception. This myth would have stemmed from the observation that yawning involves deep inhalation, which could suggest the body is trying to increase oxygen levels. However, studies have shown that oxygen or carbon dioxide levels in the blood don’t directly trigger yawning.

Why do we yawn

Drowsiness is the most common stimulus of yawn, suggests a

study. The study says that boredom occurs when the main source of stimulation in a person’s environment is no longer able to sustain their attention. This results in drowsiness by stimulating the sleep-generating system. So the mind now has to make an effort to maintain wakefulness by contacting the external environment, which could result in yawn.
Another popular theory suggests that yawning helps to cool the brain when it’s warming up. Taking a deep breath while yawning increases the blood flow and moves cooler air into the mouth and sinus cavities, which is said to help regulate brain temperature. A study suggests, “In humans and some other mammals, yawning is part of the action repertoire of advanced empathic and social skills.”

Some theories suggest that yawning is also a communication method, on how you feel, whether you’re tired, bored, or under mild stress. A few believe that yawning might help stimulate arousal and alertness by increasing blood flow and heart rate.

Though yawning is a normal behaviour found in vertebrates, excessive yawning could be a symptom of any underlying disorder. Sleep deprivation is one of the reasons for excessive yawning. Stress, insomnia, sleep apnea, and narcolepsy too are causes of excessive yawning. Sometimes, excessive yawning may be a symptom of an underlying condition such as a heart attack, stroke, bleeding around your heart, or brain tumour.
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