Sleeping on a problem really can help solve it, say scientists who found a dreamy nap boosts creative powers.

    They tested whether "incubating" a problem allowed a flash of insight, and found it did, especially when people entered a phase of sleep known as REM.

    Volunteers who had entered REM or rapid eye movement sleep - when most dreams occur - were then better able to solve a new problem with lateral thinking.

    Proceedings of the National Academy of Sciences has published the US work.

    In the morning of the test day, 77 volunteers were given a series of creative problems to solve and were told to mull over the problem until the afternoon either by resting but staying awake or by taking a nap monitored by the scientists.

    Compared with quiet rest and non-REM sleep, REM sleep increased the chances of success on the problem-solving task.

    The study at the University of California San Diego showed that the volunteers who entered REM during sleep improved their creative problem solving ability by almost 40%.

    The findings suggest it is not merely sleep itself, or the passage of time, that is important for the problem solving, but the quality of sleep.

    Lead researcher Professor Sara Mednick said: "We found that, for creative problems you've already been working on, the passage of time is enough to find solutions.

    "However for new problems, only REM sleep enhances creativity."

    The researchers believe REM sleep allows the brain to form new nerve connections without the interference of other thought pathways that occur when we are awake or in non-dream-state sleep.

    "We propose that REM sleep is important for assimilating new information into past experience to create a richer network of associations for future use," they told PNAS.

    Dr Malcolm von Schantz of the Surrey Sleep Research Centre at the University of Surrey said: "Whatever the importance of the dreams themselves are, this paper confirms the importance of REM sleep, the sleep stage when most of our dreaming takes place."

    他們測試"孵化"一個問題能否使靈光乍現，結果表示是能夠的，特別是當我們進入一個稱為REM的睡眠階段。

    參與實驗的志愿者進入較多夢的REM階段，或快速眼動期（rapid eye movement sleep）,都較能以水平思考解決新的問題。

    《國家科學研究院學報》（Proceedings of the National Academy of Sciences/PNAS）刊登美國這項研究。

    在測試當天的早上，77名志愿者給派發一連串創意問題，并需要仔細思考問題直至下午，然后選擇保持清醒地休息，或是小睡，由科學家觀察情況。

    與靜靜地休息及沒快速眼動睡眠相比，有快速眼動期睡眠的人成功地解決問題的機會增加了。

    加州大學圣地亞哥分校進行的這項研究顯示，志愿者睡覺時進入快速眼動期，解決問題的創意能力提升近四成。

    結果表示解決問題最重要的關鍵，不單是睡眠本身，或者睡眠時段，而是睡眠的質素。

    首席研究員梅德里克（Sara Mednick）教授說：「我們發現，對于思考中的創意問題，睡眠時段已能夠找出解決方法。」

    「對于解決新的問題，只有快速眼動期的睡眠，才可以提升創意能力。」

    研究員相信在快速眼動期睡眠期，大腦能不受其它思緒干擾，形成新的神經網絡，那是在清醒或無夢狀態睡眠時不能做到的。

    「新信息吸收后并融入過去經驗中，形成一個可將來使用的豐富聯想網絡，在這方面，我們認為快速眼動期扮演重要角色。」他們向《國家科學研究院學報》說。

    Surrey大學Surrey睡眠研究中心的Malcolm von Schantz博士說：「無論夢境本身有何重要，這份研究證實了快速眼動期睡眠的重要，這是睡眠中大多夢境出現的時候。」