It is one thing to learn a new piece of information, such as a new phone number or a new word, but quite another to get your brain to file it away so it is available when you need it。

　　A new study published in the Journal of Neuroscience by researchers at the University of York and Harvard Medical School suggests that sleep may help to do both. The scientists found that sleep helps people to remember a newly learned word and incorporate new vocabulary into their "mental lexicon"。

　　During the study, researchers taught volunteers new words in the evening, followed by an immediate test. The volunteers slept overnight in the laboratory while their brain activity was recorded using an electroencephalogram. A test the following morning revealed that they could remember more words than they did immediately after learning them, and they could recognize them faster demonstrating that sleep had strengthened the new memories。

　　This did not occur in a control group of volunteers who were trained in the morning and re-tested in the evening, with no sleep in between. An examination of the sleep volunteers' brainwaves showed that deep sleep (slow-wave sleep) rather than rapid eye movement (REM) sleep or light sleep helped in strengthening the new memories。

　　These results highlight the importance of sleep and the underlying brain processes for expanding vocabulary. Lead author Jakke Tamminen, said: "New memories are only really useful if you can connect them to information you already know." he said their study identifies the brain activity during sleep that organizes new memories and makes those vital connections with existing knowledge。

　　学习新知识——比如记个电话号码或者一个新单词——是一回事，而将它们存进大脑并在需要时调用就完全是另外一回事了。

　　英国约克大学和美国哈佛医学院联合在《神经科学杂志》刊登的研究论文称，睡眠能够兼修学习能力和记忆能力。科学家们发现，睡眠可以帮助人们记住新学到单词，并将其纳入“人脑词典”。

　　在研究中，研究人员在晚上教会志愿者新单词，随后立即测试。然后志愿者在实验室入睡，研究人员同时检测脑电波以观察他们的大脑活跃度。次日早晨的测试结果证明，志愿者睡后记住的单词比刚学完记住的单词还要多，并且能很快回想起新学单词，这表明睡眠有助于加强新记忆。

　　而另一组受控志愿者在早上学习，晚上测试，中间没有睡眠，研究人员发现这种学习效果差强人意。而对睡眠人员的脑电波进行监测后发现，相较于睡眠浅的志愿者，睡眠较深的志愿者的新增记忆得到了更有效的巩固。

　　这些研究结果突出了睡眠的重要性，并解释了扩充词汇量的脑部机制。研究论文主要撰稿人Jakke Tamminen称：“如果你能将新增记忆和自己已有的知识储备联系起来，新增记忆才算真正有用。”他还说他们的研究证实了人们在睡觉时大脑组织新记忆并将其与已有知识联系起来。