(2018·广东实验中学高二检测)

　　There's nothing like a good night's sleep- but what does that really mean? It turns out that the answer depends not only on your age，but also on your lifestyle. Some people are productive and happy with fewer hours of sleep，while others need more. Still，experts can determine guidelines that work for most people. The National Sleep Foundation researched the topic and gave new recommendations this week. The foundation acknowledges that sleep needs will vary- lifestyle and stress should be taken into consideration- but their recommendations offer a general guideline. For example，teenagers (14－17years old) need 8－10 hours，sleep every day.

　　To create the recommendations，some sleep and medical experts reviewed 312 articles from journals published during the last decade. This is the first time that any professional organization has developed age­ specific recommended sleep durations based on a systematic review of the world scientific literature.

　　A lack of sleep can be linked to weight gain，because that causes an increase in appetite，according to the foundation. It can also have serious consequences on the brain. People who do not get enough sleep are at increased risk for depression，and can endanger others. Those that become sleepy while driving，for example，risk both their lives and the lives of those around them.

　　Researchers also have found in the past that too much sleep can have negative effects. Low socioeconomic status and depression reportedly are significantly associated with longer sleep. However，experts nowadays find that research on oversleeping is still unconvincing and needs more attention. Currently，there is no strong evidence that sleeping too much has health consequences. There is，however，laboratory evidence that short sleep duration of four to five hours has negative consequences. We need similar laboratory studies to determine whether long sleep duration results in physiological changes that could lead to disease before we make any recommendations against sleep extension.

语篇解读　本文介绍了睡眠不足和过量睡眠可能会导致的不良后果。但是关于睡眠过量可能导致的后果，还需做进一步的研究。

5．Which is TRUE about sleeping time?

A．The time you need for sleep is related to your state of mind.

B．Experts' guideline for sleeping time applies to all the people.

C．The less you sleep，the more productive you are.

D．The more you sleep，the more energetic you are.

答案　A

解析　细节理解题。根据第一段第三句"Some people are productive and happy with fewer hours