From ages ago, theorists have attempted to solve the reasons behind yawning. Society has come to label it as a form of expression, an expression of boredom, weariness, or drowsiness. But there are other factors that spark a yawn, rather than the common misconception that tiredness plays the only factor. The reason why the concept of yawning is so perplexing is due to the involuntary notion of it. Our yawns can be triggered through a visual exposure of a yawn, mental picturing of a yawn, or sometimes even the sound or literal mentioning of the word "yawn.  Fascinated scientists have attempted to provide purely scientific reasoning for yawns; while others contest that there are social factors behind yawning. The theories are endless.
One of the oldest theories of yawning has been correlated with oxygen and the breathing patterns. As we get more fatigue, our respiratory systems tend to get lazy, which causes us to take in a drastically lower amount of oxygen. This lowers the amount of oxygen in the blood and the amount of carbon dioxide coming out of the blood. (Susan Ingraham, Why do we Yawn?, Susaningraham.net). Therefore, some claim yawning as an involuntary action to balance the oxygen and carbon dioxide levels in our bloodstream. Although seemingly plausible, this theory has been disproved through multiple studies proving that more intake of oxygen does not necessarily prevent or decrease yawning (Castro, Why do we Yawn?, livescience.com).
Others theorists state that yawning is a way of stretching and lubricating the lungs. This theory states that yawning expands the lungs and flexes the muscles and joints surrounding it, increasing the heart rate. Simultaneously, the air pockets within the lungs are coated with a chemical called surfactant. This helps keep the air pockets open and prevents the lungs from collapsing. (Ingraham, Why do we Yawn?, Susaningraham.net). Although one of the many underlying functions of yawning is to se...