遇到難題解決不了？科學告訴你，不妨先睡一覺再說！

It is often said that the best way to get to the bottom of a hard problem is to sleep on it. But how accurate is this advice?

關於如何追根究底找到解決問題的方法，通常有個普遍的說法 —— 最好先睡上一覺，或許會找到解決方案。不過這個說法到底有幾分可信度呢？

A new study forthcoming in the journal Psychological Science may have the answer.

一項即將在《心理科學期刊》刊登的最新研究報告或許能給出答案。

A team of researchers led by Kristin Sanders of Northwestern University designed an experiment to test whether cueing music associated with unsolved brain teasers during sleep increased people's ability to solve those same brain teasers the next morning. Fascinatingly, they found that it did.

美國西北大學克里斯汀·桑德斯領導的一組研究人員設計了一個實驗。在測試者睡眠期間，播放與尚未解決腦筋急轉彎相關的提示音樂，研究他們在次日早晨解決同樣問題的能力是否有所提高。實驗結果令人驚喜，測試者次日解決問題的能力確實得到了提高。

"Numerous studies in humans and other animals demonstrate better memory after sleep compared with a similar time awake," state the researchers. "Sleep-related memory processes not only strengthen but also can optimize, organize, and transform information."

研究人員稱：“根據對人類和其他動物的大量研究，在相似的時間段，睡眠之後的記憶力比清醒時效果更佳。與睡眠相關的記憶形成過程，不僅能在睡眠中得到加強的效果，還起到組織、優化、和轉換信息的作用.”

To arrive at this conclusion, the researchers invited 57 students at Northwestern University to participate in a three-day, two-night study. On the first day, participants were presented with a series of difficult spatial and verbal puzzles. Here is one example. (The answer is provided at the end of this article.)

爲了證實這個結論，研究人員邀請美國西北大學57名學生參與三天兩夜的實驗研究。第一天，測試者需要解決一系列的空間和文字難題。舉個例子：（答案於本文文末）

On a wall outside a closet door are three standard on/off switches. One (and only one) controls a light bulb inside the light-tight, well-insulated closet. The other two switches do nothing. You can only open the closet door once, and cannot change any switches after the door is open (or re-closed, for that matter). Damaging or disassembling the door, walls, or switches is against the rules. Within these constraints, how can you determine with certainty which switch controls the light bulb? — Sanders et al. (2019)

壁櫥門外的牆上有三個同樣規格的標準開關。其中有且僅有一個開關控制壁櫥內的一個燈泡，壁櫥密不透光、完全隔絕。其餘兩個開關不起任何作用。你有且僅有一次機會可以打開壁櫥門，確定你選擇的開關是否是控制該燈泡。門開之後或重新關閉前，都不可更改任何開關。禁止損毀或拆卸壁櫥門、牆以及開關，否則作違規處理。在這些約束條件下，你是如何確定燈泡的開關呢？—— 桑德森等（2019）

Forty-two puzzles like the one presented above were used in the experiment. Importantly, each puzzle was paired with a sound clip. The experimenters encouraged participants to try to solve the puzzles as well as to remember the different sound clips associated with each puzzle. Participants worked through the brain teasers until a total of six puzzles remained unsolved.

實驗中測試者需解決42道類似上述的智力題。值得一提的是，每個智力題都配備一個聲音文件。研究人員鼓勵測試者在解決智力題的同時，儘可能地記住與每個智力題相關的聲音片段。最後測試者成功解決這些問題，但還有六道尚未找到解決方法。

Next, participants took home a sleep monitoring device and sound cueing system that gathered data and played music while they slept. For instance, every time the machine detected slow-wave sleep(i.e., the type of sleep in which dreaming and memory re-organization is thought to occur), the machine cued music associated with some, but not all, of the unsolved brain teasers.

隨後，測試者帶回家一個睡眠監測設備和一個聲音提示系統設備。在他們睡眠期間，設備可收集與睡眠相關的數據以及播放音樂。例如，當機器檢測到慢波睡眠時（該睡眠狀態被認爲夢和記憶會出現重組的情況），機器便會播放部分與尚未解決的腦筋急轉彎相關的聲音片段。

The next morning, participants were asked to try to figure out the puzzles they were not able to solve the day before. The experiment was repeated later that day and night, and participants again attempted to solve the unsolved puzzles the next morning.

次日早上，再要求測試者解決前一天尚未解決的智力題，同時在當天重複前一天的實驗；到第三天早上，測試者再一次解決未解決的智力題。

Over the course of the two experimental sessions, the researchers found that participants were 55 percent more likely to solve puzzles on their second try when the corresponding sound clip was surreptitiously played while they slept. They also reported that the effect was not dependent on the type of puzzle; solve rates for both spatial and verbal puzzles increased when cued during sleep.

通過這兩次實驗，研究人員發現，在測試者睡覺時偷偷播放與未解智力題相應的聲音片段，他們在第二次解決問題的可能性高達55%。研究報告還指出這種效應與智力題的類型無關，如果測試者在睡眠期間接收到相關聲音的提示，空間和文字問題的解決率都有所提高。

The authors conclude, “By demonstrating for the first time that targeted reactivation of puzzle memories during sleep improves problem-solving the following morning, we add to a growing literature recognizing sleep as useful for both strengthening and reorganizing memory.”

研究人員總結說：“這次實驗首次證明，在睡眠期間，有針對性地重新激活未解難題的記憶，有助於提高解決該問題的能力。我們爲這方面的研究增加了有科學依據的參考文獻，讓人們認識到睡眠對於增強和重組記憶是有效果的。”

So, the next time you're faced with a difficult problem, sleep on play some music to remind yourself of the challenge.

因此，不論你遇到什麼難題，不妨先睡一覺，同時播放一些能夠提示你解決該問題的音樂，或許醒來後你就找到了解決方案。