Everyone must have evaporated, both young and old. But has it ever crossed your mind about why humans yawn? As lay people, we only know that yawning is a sign that someone is lacking sleep or sleepiness. Or is not it? It is undeniable, yawning is very closely related to sleepiness or fatigue. According to some studies, yawning can be a sign of drowsiness, fatigue, or sleep disturbance. A neurologist from the University of Maryland, United States who has been researching yawning for 30 years, said that someone yawns as a sign of fatigue. According to him, people will yawn when approaching bedtime or after waking up. In addition, yawning is thought to have something to do with boredom. The same expert conducted an experiment regarding the relationship between yawning and boredom by dividing the two groups of teenagers. The first group was given a watch about an unattractive color test, while the second group was given a watch of a music video. The results showed that adolescents in