if yawning is caused by the brain’s need for oxygen, how does that relate to being tired?

Question

if yawning is caused by the brain’s need for oxygen, how does that relate to being tired?

In: Biology

Answer 1

Excess CO2/insufficient O2 is just one proposed cause of yawning, and we still don’t know for sure what it does, what causes it, or why it’s such a conserved trait among mammals.

In terms of fatigue for some species, it’s believed to play a role in signaling tiredness to the herd, so everybody can synchronize their sleep schedules together. But again, we don’t know for sure.

It’s thought by some to be a combination of multiple functions which would explain why it’s such a highly conserved trait- it’s versatile.