Yawning

Yawning is a reflex action when the mouth opens wide to inhale and exhale air. Centuries ago, people believed that you should cover your mouth when yawning to prevent your soul from leaving your body. A yawn is controlled by the hypothalamus part of the brain and this action may cool the brain. You may yawn when your eyelids begin to droop and the yawn is your brain’s attempt to jolt you awake, possibly preventing an accident such as when driving.

The yawn is definitely contagious and many animals such as pigs, monkeys, crocodiles, snakes, fish, birds and reptiles do it. Experts don’t fully understand why we yawn and there are just three clear cut causes for yawning: lack of oxygen, being tired, or bored. One known unconscious reflex of a body function is to cool down the brain by a yawn. Excessive yawning may be triggered by sleep deprivation or medication side effects (Wikipedia).

Certain health conditions such as MS (Multiple Sclerosis), Parkinson’s Disease and Epilepsy may prompt excessive yawning due to how they affect the body’s temperature. A number of test such as EEG (Electroencephalogram), MRI (Magnetic Resonance Imaging), sleep study (Polysomnography) or a sleep diary may be used to determine what is causing excessive yawning. Due to the fact that yawning is not considered a serious side effect, it is rarely listed as a side effect on medication labels (WebMD).

One proven benefit from a forced yawn when landing in an airplane is to release the air pressure in your eustachian tubes which regulate air pressure in your inner ear.