Why don't we yawn when we sleep?

Question

You could be yawning like crazy before you go to sleep, but as soon as you start sleeping, you don't yawn anymore. What's up with that?

Answer 1

Yawning has to do with a lack of oxygen to the brain. The lack of oxygen generally causes one to be tired and therefore they yawn. While sleeping, your heart rate slows, your body is in a resting state, and your brain is getting its much needed oxygen.

Answer 2

Yawning is your body trying to keep itself awake by getting more oxygen to the brain. You'll notice that if you're not trying to stay awake, you won't yawn. Even if you're really tired, but are relaxed and trying to go to sleep, you won't yawn. It's only when your body feels like it can't fall asleep that the yawns will kick in.

Answer 3

What Happens During Sleep?
You don't notice it, of course, but while you're asleep, your brain is still active. As people sleep, their brains pass through five stages of sleep. Together, these stages - which doctors call 1, 2, 3, 4, and REM (rapid eye movement) sleep - make up a sleep cycle. One complete sleep cycle lasts about 90 to 100 minutes. So during an average night's sleep, a person will experience about four or five cycles of sleep.

Stages 1 and 2 are periods of light sleep from which a person can easily be awakened. During these stages, eye movements slow down and eventually stop, heart and breathing rates slow down, and body temperature decreases. Stages 3 and 4 are deep sleep stages. It's more difficult to awaken someone during these stages, and when awakened, a person will often feel groggy and disoriented for a few minutes. Stages 3 and 4 are the most refreshing of the sleep stages - it is this type of sleep that we crave when we are very tired.

The final stage of the sleep cycle is known as REM sleep because of the rapid eye movements that occur during this stage. During REM sleep, other physical changes take place - breathing becomes rapid, the heart beats faster, and the limb muscles don't move. This is the stage of sleep when a person has the most vivid dreams.

Answer 4

Why would you yawn when you sleep? all you need to do is breath and dream of happy places. Yawning is telling you that you need sleep.

Answer 5

I believe yawning is your body's reaction to wanting to stay awake, once asleep, the body recognizes this and knows that you can breathe slower and more regular, thus no more yawning. If you layed in bed and tried to stay awake, you would yawn...when asleep...zero...try it out

Answer 6

How do you know that you don't yawn when sleeping ?

Answer 7

yawning is a conscience action. So when were sleeping we don't yawn.

Answer 8

you yawn when you aren't breathing correctly, it's how you get large amounts of oxygen at once when you sleep you either breath normally or wake up

Answer 9

beats me I heard when you yawn it's from a lack of oxygen

Answer 10

how do you know that you dont yawn?