题型：任务型阅读 题类：模拟题 难易度：普通
北京海淀区2019届高三英语二模试卷
Sleep and Teens--Biology and Behavior
How much sleep do teens need? And how much sleep are they realistically getting? Based on current data, most teens need about 9-plus hours to have the best or most suitable sleep night.
Many factors combine to decrease sleep in adolescents. We can think in general of two major factors: biological, the brain processes that regulate the amount and timing of sleep, and behavior, all the psychological, parental, societal, cultural features of teen's life.
These changes lay the ground work for the biological night to occur later during the teen years than before. Circadian Rhythms (daily biological clock) seems to slow down as young people progress through the middle school years. At the same time, the sleep pressure system appears to change in a way that makes it easier to stay awake longer, though without changing the amount of sleep that is needed.
Moreover, many teens have a "technological playground" in their bedrooms: television, computer with 24/7 Internet access, telephones, electronic game stations, MP3 players, and so forth. These technologies provide instant and constant contact with peers. Societal and media pressure to consume these technologies is now higher than ever. Yet society also requires that teens go to school at a time of day that is at odds with their biological and social lives. So we see teens turn to caffeine, late-night Internet and cramming in activity after activity as a means to keep awake.
Problems emerge for lack of sleep. For some, grades begin to suffer as they struggle to keep awake during class and while doing homework. And others may simply feel moody, never knowing how to feel or do their best. Worse still, many teens suffer from both physical and mental illness.
The earlier teens can start this good sleep habit, the easier it will be for them to stay healthy, happy and smart.
A. Sleep experts recommend teens keep consistent sleep and wake schedule
B. Teens may schedule sleep like any other daily activity and make sleep a priority
C 
Then they are trapped into a terrible situation where they would never get enough sleep
D. The sleep-wake bio-regulatory factors appear to change significantly during adolescence
E. Some teenagers struggle to wake up in the morning 
often resulting in late or missed school
F. Teens may be driven to things that can wake them up because they'll fall asleep if they do not
G. However, it is indicated that most teens fall short of this goal, many by a considerable amount.
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