According to the survey conducted by some scientists, it is common to have difficulty sleeping during the day. Humans are naturally wired to sleep best at night and be awake during the day. However, modern work schedules require some people to try to accommodate the unnatural schedule of shift（轮班）work — being awake at night and sleeping during the day.
In order to make this adjustment, you need to pay special attention to your sleep environment and your preparation for sleep. If shift work is a necessary part of your work life, here are some suggestions that may help.
Arrange to sleep uninterrupted in a quiet, dark room. This means you may have to turn off or unplug your phone, hang darkening curtains on the windows or wear a sleep eye mask, and train your family and friends to leave you alone while you sleep.
Fit in a nap (小睡). When your daytime sleep period is too short, taking a short nap of less than 30 minutes just before work or on a break has been shown to improve alertness and enhance performance.
Develop and follow a sleep routine. It's best if you go to sleep and wake up at the same time every day. Try not to vary this too much on weekends. Your body likes routine.
Take extra care to make healthy choices. You may be tempted to reach for unhealthy foods or nicotine to stay awake or alcohol to try to sleep. But ultimately these choices are more harmful than helpful.
If you have tried all these things and are still having problems getting enough quality sleep during the day, talk to your doctor or a sleep specialist. Sometimes medications (药物治疗) may be helpful and safe. In other cases, there may be an underlying sleep disorder that needs to be addressed.
The purpose of the text is to_____ .

A．persuade workers to have a good sleep

B．advise night workers to keep healthy

C．encourage workers to do day work

D．help night workers to sleep well

What does the author recommend?

A．A suitable amount of alcohol to help sleep.

B．A regular life on weekday’s and weekends.

C．A bright room without phones to sleep in.

D．A break for sleeping anytime during the day.

On which condition should a person turn to a sleep specialist for help?

A．If he suffers from a sleep disorder for the first time.

B．If a good sleep environment is greatly needed for him.

C．If he fails to get quality sleep through his own efforts.

D．If he has the problem of falling asleep in the daytime.

We can learn from the text that_____________.

A．night workers need a long time to fall asleep

B．constant breaks at work help to improve performance

C．it is difficult to create a good sleep environment

D．night work requires people to adjust their body clocks