What causes somebody to Yawn?

Answer 1

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.

Answer 2

A yawn is a semi-automatic reflex that originates in the brain stem (the lower part of our brain that is not consciously controlled). Several different brain chemicals seem to be involved in yawning, but the mechanisms are still not understood.

We yawn for different reasons. If the brain senses a lower level of oxygen, a yawn can be triggered. A yawn does not necessarily indicate fatigue, although people do tend to yawn more when they're sleepy. This may indicate that they are not breathing deeply or yawning may help keep them awake. A study was done in which heart rate, skin temperature and muscle tension were measured in 30 young adults before, during and after yawns. They found that yawning did increase their level of arousal for a short time.

Yawning is an action that occurs throughout the animal kingdom - cats, in particular, seem to yawn a great deal. In the late 1980s several studies were done in rats, and it was found that rats yawned more in the early morning before awakening and also when they were very hungry.

Yawning also occurs when people lose interest in their surroundings (i.e., get bored). Have you ever watched someone yawn and then started doing it yourself? No one knows why yawning seems to be contagious.

Answer 3

A yawn is a reflex of deep inhalation and exhalation associated with being tired, with a need to sleep, or from boredom.
A long-standing hypothesis is that yawning is caused by an excess of carbon dioxide and lack of oxygen in the blood. The brain stem detects this and triggers the yawn reflex.
It is also claimed to help increase the state of alertness of a person. From a more scientific standpoint, yawning is caused by a build up of various allergenic compounds in the diaphragm, triggering the body's natural defense system to inhale and exhale and release these harmful airborn anomalies

Answer 4

Normal yawning may be induced when the brain or lungs are not getting enough oxygen (or when someone else yawns).

Yawning involves opening the mouth involuntarily with a prolonged, deep inhalation of air, as from drowsiness or weariness

Common Causes
Drowsiness or weariness
Disorders associated with excessive daytime sleepiness
Vasovagal reaction

Answer 5

It is the brain requiring more oxygen. Which is why when someone else yawns you do to, it is your brain making sure that it has enough in case the other person takes it all. Not very likely to happen unless in a confined space, but the brain is always on survival mode.

Answer 6

When you are sleepy, yawning is the body's way of getting a boost of oxygen into the blood and thus the brain to wake you up.

Answer 7

The build up of carbon dioxide in the lungs causes us to yawn.

Answer 8

We yawn of course when we feel sleepy, when we are hungry and we are bored..

We yawn after the other because of the transfer of a certain bacteria...

Answer 9

One general theory of why we yawn is that when we're tired, we breathe less, resulting in increased amounts of carbon dioxide and decreased amounts of oxygen in our systems.Yawning - opening our mouths wide and taking in bigger breaths of air -serves as a way to gather more oxygen into the system.

Answer 10

Seeing someone else yawn first!