What makes us yawn and why when we do, do other people start yawning too?

onlytrivial

The hypothalamus is thought to play a role in yawning. Research showed that neutrotransmitters can cause increased yawning when injected into animals, according to this site: http://faculty.washington.edu/chudler/yawning.html One theory as to why we yawn is that when we are bored (when we yawn the most), we breathe slower and take in less oxygen. As carbon dioxide builds up, we yawn to take in lots of oxyegen and get rid of carbon dioxide. As for why yawning is contagious, I presume its a psychological thing. I once read it may be due to jealousy. If we see someone else yawn, we are jealous of all the oxygen they are taking, and yawn ourselves. Sounds crazy, I know! Apr 09 05, 4:58 AM

MrsAce

See question # 56525 which also references similar questions on yawns. Apr 10 05, 12:35 AM