题目内容：

    Sleep is essential for a person’s wellbeing. Researchers have found that sleep loss increases a person’s risk of developing serious medical conditions. Now, a new study has found that getting enough sleep is also the key to improving academic performance.

Jeffrey Grossman, who led the research, was not trying to find the correlation (相关性) between sleep and grades when he handed out Fitbits to the students in his class. Instead, the professor hoped the popular wrist-worn electronic device (装置), which tracks a person’s activity 24/7, would show a connection between physical exercise and academic achievement.

As part of the research, a quarter of the participants chose a fitness class specially created for the study. After the school term ended, the researchers carefully analysed the data. Much to Grossman’s surprise, they found no measurable difference in test performance between the group that had been physically active and the group that had not.

However, the study presented a surprising viewpoint in the journal Science of Learning. Going through the large amount of data, Grossman noticed an interesting trend (走向) from the participants sleep patterns. There was a straight-line relationship between the average amount of sleep and his/her grade on the exams.

Besides, it was not enough for students to just head to bed early the night before a test. Grossman says: “We’ve heard the phrase ‘Get a good night’s sleep, you’ve got a big day tomorrow.’ It turns out this does not relate at all to test performance. Instead, it’s the sleep you get during the days when learning is happening that matters most.”

The time students went to bed each night was similarly important. Those who went to bed in the early hours of the morning performed poorly, even if the total sleep time was the same as a higher-performing student.

The research does not prove that sleep is the only component that helps improve academic performance. However, Grossman says the results are a strong indication that sleep really matters. Who knew getting A’s just required some extra ZZZ’s?

1.What’s Grossman’s original purpose by using Fitbits in the research?

A.To improve students sleep patterns.

B.To regulate students’ daily behavior.

C.To monitor students’ physical condition.

D.To find effects of physical exercise on grades.

2.What did Grossman think of the research result?

A.It was unexpected. B.It was changeable

C.It was unreliable. D.It was fruitless.

3.What plays a more important part in test performance?

A.Sleep in the learning stage. B.Average amount of sleep during tests.

C.Sleep quality the night before the test. D.A regular bedtime.

4.What is the best title for the text?

A.Be Physically Active and Sleep More

B.Enough Sleep Benefits Our Wellbeing

C.Catch ZZZ’s for Good Test Performance

D.The More Exercise, the Better Schoolwork