And my brain is experiencing decreased cerebral blood flow.

我的大脑正在经历脑血流减少。

She told the BBC that it may have started in “the days of cavemen when someone had to be on watch all the time - yawning increases cerebral blood flow so can improve alertness”.

她告诉 BBC， 这可能始于“穴居人的时代， 当时有人必须时刻保持警惕——打哈欠会增加脑血流量， 因此可以提高警觉性” 。