Why do we yawn?

Answer 1

Lack of oxygen
it is a common mistake that it is because we are tired
some people belive it is a way to communicate

*<:D

Answer 2

A yawn (synonyms chasma, oscitation from the Latin verb oscitare, to open the mouth wide) is a reflex of deep inhalation and exhalation associated with being tired, with a need to sleep, or from lack of stimulation. Pandiculation is the term for the act of stretching and yawning. Yawning is a powerful non-verbal message with several possible meanings, depending on the circumstances. It is also claimed to help increase the state of alertness of a person. The exact causes of yawning are still unknown.

The word "yawn" has evolved from the Middle English word yanen, an alteration of yonen or yenen, which in turn comes from the Old English geonian.

Hypothesized causes of yawning:
1. An indication of tiredness, stress, over-work, or boredom.
2. An action indicating psychological decompression after a state of high alert.
3. A means of expressing powerful emotions like anger, apathy, apprehension, remorse or tedium.

Answer 3

THE TRUTH IS that we don’t completely understand why people, or animals for that matter, yawn.

It’s widely assumed that yawning occurs because we are tired or bored or because we see someone else doing it, but there isn’t any hard evidence to support these beliefs.

Scientists do not purport to know all of the biological mechanisms of the yawn, but tend to agree that a yawn is an involuntary respiratory reflex, which regulates the carbon dioxide and oxygen levels in the blood.

Technically, a yawn is the reflex opening of the mouth followed by the deep inhalation and slow exhalation of oxygen.

The very act of yawning is but one of a number of involuntary reflexes controlled by the spinal and nerve centers.

Scientists speculate that the onset of a yawn is triggered either by fatigue, or by sheer boredom as, at those times, breathing is shallow, and little oxygen is carried to the lungs by the oxygen-toting cardiovascular system.

When one yawns, his or her alertness is heightened, as the sudden intake of oxygen increases the heart rate, rids the lungs and the bloodstream of the carbon dioxide buildup, and forces oxygen through blood vessels in the brain, while restoring normal breathing and ventilating the lungs.

This quite plausible theory of yawning falls short of explaining many aspects of yawning. Scientists explain away the "contagious" nature of yawning, that is when one person's yawn triggers another nearby to yawn, as due to the power of suggestion, but are at a loss when attempting to explain why yawning occurs excessively in patients with lower brainstem damage or with multiple sclerosis.

Other unlocked mysteries include why fetuses in the womb yawn, when it is a well-known fact that they do not intake oxygen into their lungs until after live birth, or why individuals with high concentrations of oxygen in their blood streams yawn.

Until these questions are answered, do not assume that a person who yawns in your presence is bored with what you are saying, or suffers from exhaustion. Simply be pleased that he or she is not bored to death.

Answer 4

We yawn because the lack of oxygen to our brain.

Answer 5

technically they say it that is because of the pooling of blood in the venous pterygoid plexus in the lateral pterygoid muscle of the face due to the lack of movt. lack of movt may be due to boredom, tiredness etc and this in turn causes sluggish flow of blood to the brain resulting in reduced oxygen supply to the brain. this reflex mechanism constitutes a deep inhalation as well as the contraction of the pterygoid and other muscles of the face resulting in the dual function of increased oxygen conc. in the blood for a greater supply to the brain and also pushing of the blood out of the plexus due to the muscular contraction, into the circulation thus increasing the rate of flow. probably this reflex is mediated by the reticular formation in the brainstem which senses the reduced oxygen tension. it is responsible for conciousness and alertness.

Answer 6

because yawning is a way our bodies regulate the carbon monoxide and oxygen in our bodies.

Answer 7

because when u get tired you start breathing in slower! so when you yawn its just your body trying to get more air! but what i wonder is how can they possibly be contagous?

Answer 8

Old wives tale is lack of oxygen.

Answer 9

to get more oxygen to the brain...

Answer 10

b/c we are tired.