Why Do We Yawn? It Does Not Indicate A Need For Sleep, Scientists Say

Science For Everyone: Yawning doesn't mean one has less oxygen in their body or excessive carbon dioxide, though many believe by yawning one tries to inhale more oxygen or get rid of carbon dioxide. 

Yawning is associated with sleeping, but it does indicate a need for sleep, according to scientists.

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Yawning: Welcome back to "Science For Everyone", ABP Live's weekly science column. Last week, we discussed why birds fly in V-formation, and the physics behind it. This week, we discuss the science behind yawning. Humans, on average, yawn about five to 20 times everyday, and each yawn lasts about five seconds. Yawning is associated with sleeping, but it does not indicate a need for sleep, according to scientists. Also, yawning does not mean that one has less oxygen in their body or excessive carbon dioxide, because many believe that by yawning, one is trying to inhale more oxygen or get rid of carbon dioxide. 

While the exact reason behind yawning is not known, it is believed to be a form of non-verbal communication, or a troop signal. Baboons use yawning as an indication to their troops that it is time to sleep. 

Check out ABP Live reports explaining the science behind different phenomena here.

People yawn when their breathing is shallow, or when they are tired, bored or have just woken up because yawning stretches out the lungs and nearby tissues, and prevents tiny airways in the lungs from collapsing. 

Athletes and musicians often yawn before performing or focusing on their work because yawning helps increase one's heart rate, stretches the muscles and joints, and prepares the body for an increased level of alertness, according to Harvard Medical School. 

Yawning is an involuntary process that helps cool down the brain, according to Andrew C Gallup, a researcher in evolutionary psychology, an article published by Penn State University said. When one begins to yawn, it causes them to stretch their jaw and inhale cool fresh air. When this air interacts with blood, the blood cools.

Gallup found that people yawn a cool day, the hypothesis would work better because cool air helps cool the brain better than warm air. 

The article said that according to Robert Provine, a neuroscientist, yawning is more frequent when a person is bored, before going to sleep, or after waking up because it could be a means to help one's mind and body transition from one state to another, and not related to how tired they are.

Humans and chimpanzees show contagious yawning, which refers to the urge to yawn on seeing others yawn, rather than spontaneous yawning. 

However, yawning is not always associated with harmless events. According to Harvard Medical School, yawning could be a symptom of a disease such as multiple sclerosis or amyotrophic lateral sclerosis, which is a rare neurological disease affecting motor neurons.

A person may also yawn before they are about to experience a migraine headache.