题型：阅读理解 题类：常考题 难易度：普通
牛津译林版高中英语高三上册模块9 Unit 2 Witnessing time 同步练习
Try this: For an entire day, forget about the clock. Eat when you're hungry and sleep when you're tired. What do you think will happen?
You may be surprised to find that your day is much like most other days. You'll probably get hungry when you normally eat and tired when you normally sleep. Even though you don't know what time it is, your body does.
These patterns of daily life are called circadian rhythms, and they are more than just habits. Inside our bodies are several clocklike systems that follow a roughly 24-hour cycle. Throughout the day and night, our internal clocks direct changes in temperature, body chemicals, hunger, sleepiness and more.
Everyone's rhythms are unique, which is why you might like to stay up late while your sister always wants to go to bed early. But overall, everyone is programmed to feel tired at night and energetic during the day.
Scientists have known for a long time that the light of day and the dark of night play important roles in setting our internal（内部的） clocks. Now, new discoveries are giving scientists insights into how these clocks work.
Learning about our body clocks may help scientists understand why problems arise when we act out of step with our circadian rhythms. For example, traveling across time zones can make people wake up in the middle of the night. Regularly staying up late can make kids do worse on tests and quizzes. And working shifts at night leads to higher rates of heart disease, diabetes and obesity.
“There is a growing sense that when we eat and when we sleep are important parts of how healthy we are,” says Steven Shea, Director of the Sleep Disorders Research Program at Brigham and Women's Hospital in Boston.
Scientists still aren't sure why the timing of sleep matters so much, Shea says. But research findings suggest that our circadian rhythms are more important than we give them credit for.
“During the night, we are prepared to sleep,” Shea says. “During the day, we are prepared to eat and move around. If you reverse (颠倒)what you are doing, everything is out of phase. That can have unfavorable consequences.”
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