Passage 1

Questions 1 to 5 are based on the following passage:

   Is that 6 a.m. workout getting in the way of good sleep? Don’t think your fat cells won't notice. A new study published in The Annals of Internal Medicine (a medical journal) finds that inadequate shut-eye has a harmful effect on fat calls, reducing their ability to respond to insulin (胰岛素) by about 30 percent. Over the long-term，this decreased response could set-the stage for type-2 diabetes (a medical condition in which someone has too much sugar in his or her blood), fatty liver disease and weight gain.

      The study adds to a growing body of evidence that there’s“an intimate relationship between the amount of sleep we get and our ability to maintain a good，healthy body weight”says sleep expert Helene Emsellem，director of the Center for Sleep and Wake Disorders in Chevy Chase，Maryland. (76) But Americans don’t seem to be getting the message that we need seven to nine hours per night. More than 1 in 5 of us，according to a report form the Centers for Disease Control and Prevention，is getting six or fewer hours of sleep per night，on average.

So how did researchers study fat cells in the Annals paper? Matthew Brady of the University of Chicago and a group of colleagues selected and persuaded seven volunteers to take part in the research project. They were all young，thin and healthy and agreed to sleep for eight nights in a sleep lab. “For four nights they were allowed to stay in bed for 8.5 hours a night，” says Brady. Then ，a month later，they came back for four additional nights—but this time they were allowed just 4.5 hours of sleep per night. And after each visit，researchers got a sample of their fat.(77) Brady explains that the fat cells responded significantly to the loss of sleep. “I was very surprised to be honest，”he says.

Bad things can happen when fat cells become less responsive to insulin. “Fat cells are actually your friend，”he says.“They’re there to store lipids(血脂).”When lipids stay inside the cells，your body can utilize the fat when you’re exercising or sleeping or going about your day.“However，when fat cells start to become insulin resistant，the lipids start to leach out of the fat cells and rise in the bloodstream，” Brady says.