why do we yawn?

Answer 1

When we're tired, we breathe less, resulting in increased amounts of carbon dioxide and decreased amounts of oxygen in our systems, yawning is- opening our mouths wide and taking in bigger breaths of air and serves as a way to gather more oxygen into the system.

Answer 2

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.

The most plausible explanation, and the one that is taught in medical school, is that we yawn because oxygen levels in our lungs are low. Studies have shown that during normal, at-rest breathing, we don’t use anywhere near our lung capacity; for the most part, we just use the air sacs at the bottom of the lungs. If the air sacs, called alveoli, don’t get fresh air, they partially collapse and the lungs stiffen a bit. As a result, it’s believed, our brain prompts the body to either sigh or take a yawn to get more air into the lungs.

But certain aspects of yawning remain even more mysterious. Fetuses, for instances, have been observed yawning in the womb, yet it’s known that they don’t take oxygen in through their lungs. And yawning seems to be a symptom of multiple sclerosis and other medical conditions, for reasons unclear.

Another puzzling phenomenon is that some male animals, men included, yawn in association with penile erection (although it’s presumptuous to assume they’re bored with their sex lives).

Answer 3

You yawn due to a brain response to lack of oxygen. People tend to yawn when they are tired or bored but it still is caused by lack of oxygen. Why you yawn when you see someone else yawn seems to be habit. You remember that you need to breath deeper too. When someone is in a situation with lack of oxygen such as too much carbon monoxide or a very full room with no fresh air the yawning reflex draws in ore air and is a sign to get into a fresher air environment.

Answer 4

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, rejection, apathy or tedium.
4.Caused by low oxygen in the blood

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. The mouth stretches wide and the lungs inhale deeply, bringing oxygen into the lungs and hence to the bloodstream. It is almost certain, however, that this hypothesis is not correct. One study has documented that this effect does not exist.[2]

A more recent hypothesis is that yawning is used for regulation of body temperature. Another hypothesis is that yawns are caused by the same chemicals (neurotransmitters) in the brain that affect emotions, mood, appetite and other phenomena. These chemicals include serotonin, dopamine, glutamic acid and nitric oxide. As more of these compounds are activated in the brain, the frequency of yawning increases. Conversely, a greater presence in the brain of opiate neurotransmitters such as endorphins reduces the frequency of yawning. Patients taking the serotonin reuptake inhibitor Paxil (Paroxetine HCl) have been observed yawning abnormally often. Another theory is that yawning is similar to stretching. Yawning, like stretching, increases blood pressure and heart rate while also flexing many muscles and joints. It is also theorized that yawning helps redistribute an oil-like substance which coats the lungs and aids breathing. Some have observed that if you try to stifle or prevent a yawn by clenching your jaws shut, the yawn is unsatisfying. As such, the stretching of jaw and face muscles seems to be necessary for a good yawn.

Answer 5

Yawning is a reflex action of the body in need of more oxygen. In general yawning is reflexive. The person's body is seeking more oxygen than it has right now.

Answer 6

We yawn when we are in a setting we are comfortable with. It is your brain trying to increase your oxygen level when you are content and you are relaxing, the reason it is trying to increases your oxygen level is because there is a point of interest and your brain and body are fighting in a sense: trying to stay awake and trying to relax at the same time.

Answer 7

The need for Oxygen makes us to Yawn....

This is a mechanism which helps us to take in more air and hence provide more oxygen.....

Answer 8

When the lungs at heart are out of sync we yawn. This happens most often when we don't get enough rest and are pushing our bodies.

Answer 9

Try this link:
http://en.wikipedia.org/wiki/Yawn

Answer 10

it's a signal that we need to rest and recharge...
it's one of the miracles of the human body that engineers have gone crazy trying to imitate...
so when you yawn....take a nap....lol