A study by public health scientists has revealed that getting too much or too little sleep can prematurely age your brain by up to seven years.
公众健康专家发布的报告称，过多或过少的睡眠都会使大脑早衰，最多可早衰7年。

They found that middle-aged adults whose sleep decreased to less than six hours a night over a five-year period suffered lower scores in reasoning and vocabulary tests.
科学家发现连续5年每晚睡眠少于6小时的中年人在关于推理和词汇的测试中得分较低。

Those whose nightly sleep increased to more than eight hours also showed signs of accelerated cognitive decline.
那些每晚睡眠超过8个小时的人也表现出感知能力衰退的迹象。

But they found that women who had maintained seven hours of sleep per night performed best in cognitive tests as did men who slept between six and eight hours.
科学家发现每晚睡7小时的女人和每晚睡6-8小时的男人在感知能力测试中表现最好。

The findings suggest that regularly sleeping for seven hours during the night can help to reduce the cognitive decline that occurs as we grow older.
这项发现表明每晚睡7小时，能减少大脑早衰。