Why do we yawn when we are tired?

Question

is it just natures way of saying- Get To Bed ?
love
Jo xx

Answer 1

Its to increase the oxygen content to your braine

Answer 2

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.

Answer 3

It does appear that the PVN of the hypothalamus is, among other things, the "yawning center" of the brain. It contains a number of chemical messengers that can induce yawns, including dopamine, glycine, oxytocin and adrenocorticotropic hormone (ACTH). ACTH, for one, surges at night and prior to awakening, and induces yawning and stretching behavior in humans. The process of yawning also appears to require production of nitric oxide by specific neurons in the PVN. Once stimulated, the cells of the PVN activate cells of the brain stem and/or hippocampus, causing yawning to occur. Yawning likewise appears to have a feedback component: if you stifle or prevent a yawn, the process is somewhat unsatisfying. The stretching of jaw and face muscles seems to be necessary for a yawn to be satisfying.

Answer 4

by the end of the day, or when you lack sleep, the amount of carbon dioxide in your brain is a bit to much to keep. So your body yawns to let out as much carbon dioxide as it can while replacing it with oxygen. that's why you seem to exhale alot. yawning goes to show that your body is trying to stay awake even though it's suppose to be asleep. so when you yawn, give yourself a break. 5-10mins or so, or better yet go under the covers.

Answer 5

One theory is that when we are bored or tired, we just don't breathe as deeply as we usually do so our bodies take in less oxygen because our breathing has slowed. Therefore, yawning helps us bring more oxygen into the blood and move more carbon dioxide out of the blood.

Answer 6

Lack of oxygen to the brain. Yawning allows more oxygen in than simple breathing.

Answer 7

When you are tired your body is tired so it is working slower and not taking in the required amount of Oxgyen so you yawn to make up for it.

Answer 8

when you yawn, your body is letting you know that your brain isn't getting enough oxygen. opening your mouth as wide as possible and inhaling is the way the body gets more o2 to the brain

Answer 9

when we are very tired our bodies forget to take in enough breath. so we yawn to take in enough or extra oxygen to waken our selves up.

its the same thing as when we are tense we breath shallow. so we inhale sharply and exhale with a sigh to bring in more oxygen.

its our bodies natural defence mechanism.

good night jo

Answer 10

ppl yawn cuz not enough oxygen is getting to the brain; yawning is a way to increase the amout. ^.^

Answer 11

As others have said Jo it is a reflex action in response to lack of oxygen which makes you tired in the first place! x