Why Do People Yawn? What Does Yawning Mean?

It is common and normal for humans to yawn occasionally, but why exactly do people yawn?

(Photo: Pexels / Andrea Piacquadio)

Yawning Explained

Yawning, or oscitation, refers to opening the mouth and airway to take a deep and long breath.

The muscular movement itself is quite complex. In seconds, the whole airway dilates or expands fully while the muscles surrounding it tense or stretch powerfully. This is most significant around the pharynx.

Yawns typically last four to seven seconds.They involve a long inhale, a short episode of strong muscle stretch around the throat and mouth, and a rapid exhale.

Because it is mostly involuntary, yawning is a behavior that people do not have much control over. Most scientists consider it a reflex.

However, a person can induce yawning by gradually breathing in a while, retracting the tongue's tip, and opening the jaw repeatedly. Witnessing someone else yawn typically triggers one.

ALSO READ: Why Are Yawns Contagious in Both Animals and Humans? Scientists Describe This Synchronized Group Behavior

Why Do People Yawn?

Researchers have widely debated the purpose of yawning, and no clear consensus has been reached. Three primary theories explain the behavior.

The first one is the arousal hypothesis, which claims that yawning can help activate or wake up the brain. The theory is connected to the fact that boredom and tiredness usually trigger yawning. Boredom could trigger drowsiness by stimulating the body's sleep-signaling system. Researchers believe that the body needs to maintain contact with the environment effortfully during this moment, so it uses yawning to keep itself awake and alert.

When a person yawns, their heart rate increases, which can help them remain alert. During a yawn, several facial muscles stretch and tense, which can also keep them awake.

Another theory is the brain-cooling hypothesis, which suggests that yawning decreases the brain's temperature because of excess air intake and facial blood flow changes. Both human and animal studies show that yawning occurs during, before, and after abnormal thermoregulation, such as hyperthermia or heat stress.

The last theory is the communication hypothesis, which is grounded on how contagious yawning is. Supporters of this notion believe that yawning serves as a function of group synchronization or communication. These researchers believe it could signal stress or boredom to the surrounding people. Most researchers believe that social interaction is a minor yawning function that works with another more significant function.

The theory primarily accepted for several years is that yawning brings in more oxygen for the body. The theory was discarded recently as studies showed that a lack of controlled oxygen does not lead to more yawning. This theory also does not explain why fetuses yawn, as they get their oxygen supply from blood through their umbilical cord.

Evidence has also shown that yawning can be triggered by boredom, waking up, stressful events, hunger, yawn imitation, thinking or reading about yawning, and hearing or seeing a yawn.

Given the complex neurological, biological, behavioral, and mechanical influences of yawning, it largely remains a mystery. It is hard to know the end and start of one influence.