题目内容：

    Unexpected connection between sleep and academic performance has been recently discovered.

Researchers have found that insufficient sleep and tiredness increase a person's risk of developing severe medical conditions, such as obesity （肥胖症），high blood sugar levels, and heart disease. Now, a new study has found that getting sufficient sleep is also the key to improving academic performance.

Jeffrey Gross, the university science professor who led the research, was not trying to find the relationship between sleep and grades when he handed out smartwatches to the 100 students in his chemistry class. Instead, the professor hoped the wrist-worn devices, which track a personas physical activity, would show a connection between exercise and academic achievements.

While Grosses data showed no relationship between these two factors, the study found something surprising. As the researchers were analyzing their data, they noticed that there was a linear （线性的）relationship between the average amount of sleep the students got and their results in the course's 11 quizzes, three midterm tests, and the final exam.

Even more interesting, it was not sufficient for students to just head to bed early the night before a test Instead, it's the sleep you get during the days when learning is happening that matters most.

When 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. "When you go to bed matters," Gross says. “If you go to bed at 10, or 12, or 1 at night, and sleep for seven hours, your performance is the same. But if you go to bed after 2, your performance starts to go down even if you get the same seven hours' sleep. So, quantity isn't everything."

Perhaps the most interesting was the huge impact that small differences in sleep patterns had on the students' grades. The overall course grades of students averaging six and a half hours of sleep each night were 25% lower than students who averaged just one hour more sleep. Similarly, students who varied their bedtime by even one hour each night had grades that dropped 45% below those with more regular bedtime.

Who knew getting straight AM just required some extra sleep?

1.Based on his original objective, which best describes Professor Gross's research findings?

A.Convincing. B.Complete.

C.Accidental. D.Doubtful.

2.Who were the people taking part in the study?

A.Middle school chemistry students.

B.Volunteers from different universities.

C.University student athletes.

D.Professor Gross's own students.

3.How did Professor Gross's team measure students' academic performance?

A.Making the students wear special watches.

B.Using the students' normal test and quiz grades.

C.Giving the students regular quizzes after class.

D.Using students' university entrance test results.

4.Based on the study's fin dings, who is likely to perform best academically?

A.A student who has a good night's sleep the night before an important test.

B.A student who sleeps from 11 pm to 6 a.m. each day.

C.A student whose normal bedtime varies between 9 p.m. and 12 p.m.

D.A student who sleeps for a total of 7 hours each night.