Why do we Yawn???

Question

I know its a reaction to stress and getting tired but why do we yawn? How does it form?

Answer 1

You yawn when your brain needs oxygen. That is why people with concussions or traumatic brain injuries yawn a lot.

Answer 2

Everyone yawns - babies, kids, teenagers, adults. Some birds, reptiles and most mammals also yawn. However, the reason why we yawn is a bit of a mystery. There is also very little research about yawning because for most people yawning is not a problem. Here are a few things that are known about yawns:

The average duration of a yawn is about 6 seconds.
In humans, the earliest occurrence of a yawn happens at about 11 weeks after conception - that's BEFORE the baby is born!
Yawns become contagious to people between the first and second years of life.
A part of the brain that plays an important role in yawning is the hypothalamus. Research has shown that some neurotransmitters (for example, dopamine, excitatory amino acids, nitric oxide) and neuropeptides increase yawning if injected into the hypothalamus of animals.




Many people assume that we yawn because our bodies are trying to get rid of extra carbon dioxide and to take in more oxygen. This may make some sense. According to this theory, when people are bored or tired, they breathe more slowly. As breathing slows down, less oxygen makes it to the lungs. As carbon dioxide builds up in the blood, a message to the brain results in signals back to the lungs saying, "Take a deep breath," and a yawn is produced.

. In 1987, Dr. Robert Provine and his coworkers set up an experiment to test the theory that high carbon dioxide/low oxygen blood content causes yawning. Air is normally made up of 20.95% oxygen, 79.02% nitrogen), 0.03% carbon dioxide and a few other gases in low concentrations. The researchers gave college students the following gases to breathe for 30 minutes:

Gas #1 = 100% Oxygen

Gas #2 = 3% Carbon dioxide, 21% Oxygen

Gas #3 = 5% Carbon dioxide, 21% Oxygen

Gas #4 = Normal Air

Breathing 100% oxygen (Gas #1) or either carbon dioxide gas (Gas #2 and #3) did cause the students to breathe at a faster rate. However, neither carbon dixoide gas nor 100% oxygen caused the students to yawn more. These gases also did not change the duration of yawns when they occurred.

The researchers also looked for a relationship between breathing and yawning by having people exercise. Exercise, obviously, causes people to breathe faster. However, the number of yawns during exercise was not different from the number of yawns before or after exercise. Therefore, it appears that yawning is not due to CO2/O2 levels in the blood and that yawning and breathing are controlled by different mechanisms.


Dr. Provine suggests that perhaps yawning is like stretching. Yawning and stretching increase blood pressure and heart rate and also flex muscles and joints. Evidence that yawning and stretching may be related comes from the observation that if you try to stifle or prevent a yawn by clenching your jaws shut, the yawn is somewhat "unsatisfying." For some reason, the stretching of jaw and face muscles is necessary for a good yawn.

In 2007, researchers proposed that yawning is used to cool the brain. They found that people yawned more often they pressed a warm or room temperature towel against their heads than when they pressed a cold towel against their heads. People who breathed through their noses (thought to reduce brain temperature) did not yawn at all.

Answer 3

Oxygen. We yawn when we are lacking oxygen which happens often when we are tired so we suck air in and bring oxygen to our brains etc. I'll post from a link in a sec.

A previous 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.

A recent hypothesis by Gordon Gallup of the University of Albany states that yawning may be a means to keep the brain cool. Mammalian brains operate best when they are cool. In an experiment, he showed several groups of people videos of other people yawning. When the subjects held heat packs up to their heads while viewing the videos, they yawned often. But when they held cold packs up to their heads or breathed through their noses (another means of brain cooling), they did not yawn at all.

Answer 4

It has something to do with a lack of oxygen and the need to take a deep breath. Maybe shallow/slow breathing when you're tired or stressed (which can make you tired).

Answer 5

It's not from stress. it is your brain reacting to lower levels of oxigen, and telling your spleen to expand to overfill your lungs with additional air.
Usaully happens when your tired because your breathing slows down and your getting less oxygen.

Answer 6

We yawn when we need a large amount of oxygen.

Answer 7

it's cuz r mouth is in the same position and we have to move it

Answer 8

to get more qxygen to ur lungs wen they need it...
something like refresing ur lungs...

Answer 9

because we see this question so often