Sleeping more than eight hours a day is associated with a higher risk for stroke, a new study has found.
一项新研究发现，每天睡眠超过八小时与更大中风风险有关联。
Researchers studied 9,692 people, ages 42 to 81, who had never had a stroke. The study tracked how many hours a night the people slept at the beginning of the study and how much nightly sleep they were getting four years later. Over the 10-year study, 346 of the study subjects suffered strokes.
研究对象为9692名42岁至81岁的人，研究开始前他们从未发生过中风。研究人员记录了这些人在研究开始时及四年后每晚的睡眠时间。在十年的研究中，有346名研究对象中风。

After controlling for more than a dozen other health and behavioral variables, the researchers found that people who slept more than eight hours a day were 46 percent more likely to have had a stroke than those who slept six to eight hours.
在控制了十多项其他健康和行为变量之后，研究者们发现，每晚睡眠超过八小时的人比睡六至八小时的人患中风的可能性高46%。
The study, published online last week in Neurology, also found that the risk of stroke was higher among people who reported that their need for sleep had increased over the study period.
这项研究上周发表在《神经学》周刊(Neurology)的网站上。研究还发现，在研究过程中，自称睡眠需求增大的人中风的风险更大。
The authors caution that the data on sleep duration depended on self-reports, which can be unreliable. In addition, the study identified an association between sleep and stroke risk, rather than cause and effect. Sleeping more may be an early symptom of disease that leads to stroke, rather than a cause.
作者们警告说，睡眠时间数据基于研究对象的自我报告，也许不可靠。另外，这项研究只是表明睡眠和中风风险之间存在联系，并不是存在因果关系。睡得更多可能是导致中风的疾病的早期征兆，而非中风起因。
“It could be that there’s already something happening in the brain that precedes the stroke risk and of which excessive sleep is an early sign,” said the lead author, Yue Leng, a doctoral candidate at the University of Cambridge.
“可能在中风风险出现前，大脑已经发生了某种变化，过量睡眠是其早期迹象之一，”这项研究的主要作者、剑桥大学博士研究生岳伦（音译）说。
In any case, she added, “we don’t have enough evidence to apply this in clinical settings. We don’t want people to think if they sleep longer it will necessarily lead to stroke.”
她补充说，不管怎样，“我们没有足够的证据把研究结果用到临床上。我们不想让人们认为，睡得更久一定会导致中风。”