It turns out that nodding off in class may not be such a bad idea after all, as a new study has shown that going to sleep shortly after learning new material is the best way to remember it。

　　According to US lead author Jessica Payne, a psychologist at the University of Notre Dame in Indiana, nodding off after learning something new is like ‘telling’ the sleeping brain what to retain。

　　Along with colleagues, she studied 207 students who habitually slept for at least six hours per night。

　　Participants were randomly assigned to study declarative, semantically related or unrelated word pairs at 9am or 9pm, and returned for testing 30 minutes, 12 hours or 24 hours later。

　　Declarative memory refers to the ability to consciously remember facts and events, and can be broken down into episodic memory (memory for events) and semantic memory (memory for facts about the world)。

　　People routinely use both types of memory every day – recalling where we parked today or learning how a colleague prefers to be addressed。

　　At the 12-hour retest, memory overall was superior following a night of sleep compared to a day of wakefulness。

　　At the 24-hour retest, with all subjects having received both a full night of sleep and a full day of wakefulness, subjects' memories were superior when sleep occurred shortly after learning, rather than following a full day of wakefulness。

　　‘Our study confirms that sleeping directly after learning something new is beneficial for memory. What's novel about this study is that we tried to shine light on sleep's influence on both types of declarative memory by studying semantically unrelated and related word pairs,’ Payne said。

　　‘Since we found that sleeping soon after learning benefited both types of memory, this means that it would be a good thing to rehearse any information you need to remember just prior to going to bed. In some sense, you may be “telling” the sleeping brain what to consolidate.’

　　Results of the study were published on March 22 in PLOS One。

　　看來在課堂上打瞌睡也許并不是壞事。一項新研究顯示，學完新知識后馬上打個小盹是最佳的記憶方法。

　　該研究的主要作者、美國印第安納州諾特丹大學的心理學家杰西卡•佩恩認為，在學完新東西后打個盹就像把要記住的東西“告訴”睡眠中的大腦。

　　她和同事一起對207名學生進行了研究，這些學生習慣每晚至少睡六個小時。

　　參與者被隨機分配到幾個學習小組，學習內(nèi)容是陳述性知識，包括語義相連或不相連的詞組。學習時間在早上9點或晚上9點。學完后他們在30分鐘、12小時或24小時后回來做測試。

　　陳述性記憶指的是有意識地記憶事實和事件的能力，可以分為情節(jié)記憶(對事件的記憶)和語義記憶(對事實類知識的記憶)。

　　人們每天都會例行運用這兩種記憶——回想今天我們把車停在了哪里或了解一個同事喜歡別人怎么稱呼他。

　　在12小時后再次進行測試時，總體來看睡了一夜的人相比還沒睡覺的人記憶效果更好。

　　在24小時后再度測試時，所有的實驗對象都睡了一整夜，也在清醒中度過了一個白天。這次，那些在學習后不久就入睡的人比那些學習后過了一整個白天才睡覺的人記憶效果更好。

　　佩恩說：“我們的研究證實，在學習新東西后馬上睡覺對記憶有幫助。這項研究的創(chuàng)新之處在于，我們試圖通過對語義相連和不相連的詞組的記憶研究來揭示睡眠對于兩種陳述性記憶的影響。”

　　“我們發(fā)現(xiàn)在學習之后很快就睡覺對兩種記憶都有幫助，這意味著在上床睡覺前溫習你要記憶的東西將很有好處。在某種意義上，你可能在‘告訴’睡眠中的大腦需要鞏固強化的記憶。”

　　該研究的結(jié)果于3月22日發(fā)表在《科學公共圖書館—綜合》期刊上。