Regardless of nation, races or culture, all human yawn. It has been observed in humans as early as the first three months after conception. The average yawn lasts for about 6 seconds. A stifled yawn is never as enjoyable as the completed yawn. Yawning can be an indication that there is something wrong in one’s health. Frequent yawning can be a sign of cholera, encephalitis, brain lesions or hemorrhage. Yawning has always been associated with boredom and sleepiness. But its function is totally opposite from these. Its function appears to be to wake us up.
Whenever we yawn, our larynx and pharynx expand which allows large volume of air to pass into our lungs which sends a wave of cool blood to the brain. This gives the brain a cooling effect which heightens attentiveness and makes us more alert.
The human brain works to its maximum when it is cool much like a computer. Such conditions as fatigue and stress cause our brain to heat up. That is why we find it hard to concentrate whenever we are stressed and even when sleep deprived. Although yawning appears to have a positive result on the human brain, there are still people who rarely yawn. They are the psychotics.
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