【英语时差8,16】起床时间到啦（在线收听）

Yael: It's time once again for the mailbag. Let's see what we have today. Dear A Moment of Science: I went to sleep one time and slept for twenty years. What in the world happened to me? Signed Rip. Don: Well, Rip, you came to the right place. What happened is that your circadian rhythms got screwed up. Y: Circadian rhythm. That's named after those insects that come out of the ground every seven years isn't it? D: No, no. Those are cicadas. This is circadian. It's from the Latin for "about a day." Y: I knew that. D: Anyway, the brain has an internal clock that affects a lot of bodily functions, such as temperature, when we get hungry, hormone levels, and so forth. Scientists believe this clock also governs when we go to sleep and when we wake up. Y: I think I see how this clock works. We usually go to sleep at about the same time every night, and for most of us about eight hours later we wake up. D: Right. It's believed that we fall asleep at about the same time each night because chemical activity in the brain induces sleep. Then for most of us about eight hours later our brain clock switches on chemical activity that wakes us up--assuming the neighbor's barking dog doesn't awaken us first. Y: That's cool. With all this talk about sleep, I think I'm ready for a nap. D: Me too.