文章大意:这是一篇说明文。文章主要讲了一项针对老年人的多年研究发现,短时间睡眠者和长时间睡眠者的认知能力都比睡眠适量的人衰退得更严重,即使考虑到早期阿尔茨海默病的影响。
Like so many other good things in life, sleep is best at a right length. A multi-year study of older adults found that both short and long sleepers experienced greater cognitive (认知的) decline than people who slept a proper amount, even when the effects of early Alzheimer's disease were taken into account.
“Our study suggests that there is a middle range, or ‘sweet spot’, for total sleep time where cognitive performance is stable over time. Short and long sleep time is associated with worse cognitive performance,” said first author Brendan Lucey, an associate professor of the Washington University Sleep Medicine Center. “An unanswered question is if we can intervene to improve sleep, would that have a positive effect on their cognitive performance so they no longer decline? We need more further data to answer this question.”
Lucey and colleagues turned to volunteers who participate in Alzheimer's studies through the university's Charles F. and Joanne Knight Alzheimer Disease Research Center. Such volunteers experienced annual clinical and cognitive assessments, and provided a blood sample to be tested. For this study, each participant slept with a tiny EEG monitor attached to their heads for four to six nights to measure their brain activities during sleep.
The researchers found a U-shaped relationship between sleep and cognitive decline. Overall, cognitive scores declined for the groups that slept less than 4.5 or more than 6.5 hours per night while scores stayed stable for those in the middle of the range.
The U-shaped relationship held true for measures of specific sleep phases, including rapid-eye movement (REM), or dreaming sleep and non-REM sleep. Moreover, the same is true even after adjusting for factors that can affect both sleep and cognition, such as age, sex, levels of Alzheimer's proteins. “It was particularly interesting to see that not only those with short amounts of sleep but also those with long amounts of sleep had more cognitive decline,” said Professor Beau M. Ances.
“Each person's sleep needs are unique, and people who wake up feeling rested on short or long sleep schedules should not feel forced to change their habits,” said co-senior author David Holtzman, MD. “But those who are not sleeping well should be aware that sleep problems often can be treated.”
12. What's the passage mainly about?
A.The effects of Alzheimer's disease. | B.The benefits of best sleep. |
C.The influence of sleep time on cognition. | D.The good things in life. |
13. According to the passage, which sleep time is suitable?
A.4 hours. | B.6 hours. |
C.7 hours. | D.7. 5 hours. |
14. What can we know about U-shaped relationship?
A.The sleep time has no connection with cognitive scores. |
B.The longer sleep time is, the higher cognitive scores are. |
C.Cognition is related to different sleep phases. |
D.It is not effective when age, sex, and so on are considered. |
15. What does David Holtzman's words imply?
A.Quality of sleep is the key. |
B.Long time sleepers do not have cognitive decline. |
C.Short sleep schedules must change their habits. |
D.Both long time and shot time sleepers have sleep problems. |