题目内容：

If you’re looking for a fairly painless way to lose weight, researchers at Brigham Young University have a new solution for you: Put yourself on a regular sleep schedule. People who keep a regular sleep routine have a lower body fat than those who keep irregular sleep hours, says a new study.

Led by Bruce Bailey, professor of exercise science, researchers followed 300 female college students aged 19 to 26, who were given activity trackers（跟踪器）to watch their movements and activities, including waking and sleeping times . Researchers also measured their body composition (成分)before and after the one-week study period.

What the researchers found:

Body fat varied with sleep quantity. Women who slept between 8 and 8.5 hours a night had the lowest body fat. While those who slept less than 7 hours or over 9 hours had higher body fat.

High quality sleep was associated with lower body fat while poor sleep was connected with higher body fat.

Waking and going to sleep at the same time every day was most strongly linked with lower body fat.

The difference in body weight was greater with more variation（变化）in sleep pattern. Women whose sleep patterns varied by 90 minutes a night had higher body fat than those whose sleep patterns varied by 60 minutes or less on average.

The study followed up on a body of research conducted over the last few years that ties quality and quantity of sleep to weight loss and better weight control. While researchers don’t know exactly how sleep schedules affect body weight and fat, other studies have shown that sleep has an effect on physical activity, appetite（胃口）, and the hormones（荷尔蒙）that control metabolism（新陈代谢）, and the signals that tell us we’re full.

1.Which of the following about the study led by Bruce Bailey is true?

A. The participants included both females and males.

B. The participants’ activities were monitored through trackers.

C. The participants’ body composition were measured only after the study.

D. The study was controlled by researchers during a long period time.

2.Who may have the lowest body fat according to the study?

A. Women whose sleep patterns varied by 90 times a night.

B. Women whose sleep patterns varied by 60 times a night.

C. Women who sleep no more than 7 hours a night.

D. Women who get 8 to 8.5 hours of sleep a night.

3.It can be inferred from the last paragraph that ______.

A. It’s the first research to study better weight control.

B. Many people know exactly how sleep affects body fat.

C. Sleep can affect people at least in three ways.

D. Sleep can give signals to tell people they are full.

4.What does the passage mainly talk about?

A. Several factors that affects the sleep quality.

B. Some ways to help you lose weight efficiently.

C. The importance of having a regular sleep routine.

D. A study on the relationship between sleep and body weight.