单选题：If you are worried about things and are under a lot of stre

If you are worried about things and are under a lot of stress at work or school，then you are probably not sleeping well．Worry can keep you awake，tossing and 26 in bed until the early hours of the morning when you eventually27asleep．When you wake up，you don’t feel 28，but tired and worn out and 29 to face a new day．
Dr．Henry Winkle，in a recent newspaper article30 Stress and Sleep，31 that stress and lack of sleep are directly32．Dr．Winkle says，“the more we worry，the33 we sleep，the more we are unable to deal with34．”“If we can find a way to get a good night’S sleep，”he 35．“we can often find the36 to deal with what’S worrying US．”
So,what is a good night’s sleep ? Research shows that the amount of sleep which people need in order to keep healthy37a lot．Seven hours is about the average amount，38strangely enough，sleeping longer often gives you a headache 39 0f making you feel more refreshed.
Dr．Winkle believes that preparing for sleeping is important．People who work late should try to give themselves a short40and do something restful before going to bed．This could be watching TV or listening to music．Doing some exercise41in the day should help you to feel physically as well as42 tired．A bedtime drink Can also help，but coffee or tea should be avoided as they contain caffeine(咖啡因)and will keep you 43．“When you put the light 44，”Dr．Winkle says，“concentrate on relaxing your muscles．Working slowly up from your feet，and you’11 be asleep45 you know it．”
根据以上内容，回答题。
A．turning
B．rolling
C．twisting
D．rotating