题目内容：
Questionsare based on the following passage.Once again, science supports what your grandmother told you: A good night's sleep helps your body fight a cold.
People who 47 fewer than seven hours of sleep per night in the weeks before being 48 to the Cold virus were nearly three times as likely to get sick as those who averaged eight hours or more, a new study found.
Researchers used frequent telephone 49 to track the sleep habits of more than 150 men and women aged 21 to 55 over the course of a few weeks. Then they exposed the 50 to the virus, quarantined them for five days and kept track of who got sick.
51 sleeping more, sleeping better also seemed to help the body fight illness: Patients who fared better on a measure known as "sleep efficiency"--the percentage of time in bed that you're 52 sleeping--were also less likely to get sick.
The results held true even after researchers adjusted for 53 such as body-mass index, age, sex, smoking and pre- existing antibodies to the virus, Like your grandmother, the researchers aren't exactly sure why sleeping better makes you less likely to develop a cold.
But they do take a stab at the answer: "Sleep 54 influences the regulation ofproinflammatory cytokines, histamines, and other symptom mediators that are released in 55 to infection." In plain English, maybe tossing and turning when you're infected with the cold virus 56 to the symptoms that define a cold.
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