Why do we yawn when we are tired?

[¡Cereal Killer!]

That has been bugging me all weekend!

 

[Stumpy Tim]

Because the brain needs more oxygen, and that's what yawning does. Also, when you see someone else yawn your brain tells you that you need more oxygen so you tend to yawn too

 

[¡Cereal Killer!]

wow! didn't know that!

so we become tired when the brain is low on oxygen and adding 2 and two is making me think that when the oxygen in the brain is vert low, we fall asleep right?

 

[Stumpy Tim]

erm.... maybe

 

[NickL]

The reason we yawn is because oxygen levels in our lungs are low. During normal, at-rest breathing, we don’t use anywhere near our lung capacity, we just use the air sacs at the bottom of the lungs. If the air sacs don't get enough oxygen, they partially collapse and the lungs stiffen a bit. As a result, it’s believed, our brain prompts the body to either sigh or yawn to get more air into the lungs.

 

[Cheeky Monkey]

That has been bugging me all weekend!

Without wanting to diss you too much CK, you must be thick as pigshit not to know that. Next time reach for a reference book rather than posting your ignorance on here.

 

[Lush]

So why do we yawn when we wake up in the morning then? Is it because we've been sleeping with our heads under the covers?

ALSO do you yawn when you see this smiley?

 

[Seagullible]

ALSO do you yawn when you see this smiley?

Yes, just had a yawning fit - but could also be due to being tired as was in work for 6 today

 

[NMH]

It's a way to find out if a bird is looking at you discretely.

That's why yawning was invented.

 

[Man of Harveys]

That smiley looks like someone saying "wow" with their eyes shut, not a yawn.

 

[Tesco in Disguise]

why yawns are infectious seems odd. just cos someone else needs oxygen doesn't mean you do. i thought the brain was supposed to be smart.

 

[turienzo's lovechild]

i once thought that there was just one yawn that went all the way round the world

 

[Le Premier Cru]

Palace on tour?

 

[Lammy]

Anyone else been yawning whilst reding this thread?

 

[Trufflehound]

i once thought that there was just one yawn that went all the way round the world

That'll be the Mexican yawn...