Trying to Solve a Problem? Sleep on it!
By Carolina Kuepper-Tetzel
A while ago we featured a blog post on sleep and memory. In today’s post, I want to give an overview of the benefits of sleep on problem-solving and creativity.
To find a solution to a problem, students need to restructure the problem in a way that allows seeing it from different angles. The sudden realization of the problem solution is referred to as insight and is usually described as an “Ah-ha” experience. Insight is a key factor when solving a problem and it is often accompanied by a “feeling of warmth” (1). One way to facilitate insight and, thus, to get closer to the solution of a problem is incubation. Incubation means that one comes up with a solution to a problem after spending time away from it: One form of incubation is sleep. But why should sleep help problem solving at all? The idea here is that when you spend some time trying to solve a problem without success, you have tried different ways and approaches. This leads to the accumulation of numerous failed strategies which decreases the chance of solving the problem. It is assumed that during sleep misleading information and dead ends are being forgotten which allows one to return to the problem with a fresh mind.
In one study by Beijamini, Pereira, Cini, and Louzada (2), participants played a video game, but soon reached an impasse and could not proceed. One half of the participants were then given the opportunity to take a 60-min nap whereas the other half stayed awake during that time. Afterwards, participants returned to the video game. The results were impressive: Compared to participants who stayed awake, participants who had slept were twice as likely solve the puzzle in the video game and overcome the obstacle! In another study (3), participants had to solve math puzzles using two simple rules. However, the puzzles could also be solved with a difficult to find short cut of which participants were not aware of. After a practice period, participants either slept or stayed awake during an 8-hr interval. Participants were then given new math puzzles to solve: About 60% of the participants in the sleep condition discovered the hidden short cut, whereas only 23% of participants in the wakefulness condition managed to find it. This is remarkable because at no point in the study were participants told that there was a hidden short cut and yet participants who had slept were twice as likely to spontaneously detect and use it.
Since problem solving requires the restructuring of a problem in novel ways, creativity has been identified as a factor supporting that process. Creative solutions to problems are original, i.e., not many people will come up with the type solution, and relevant, i.e., the proposed strategy is actually a valid solution to the problem. In one study (4), participants took the Remote Associates Test. In this test, participants are presented with three seemingly unrelated words, e.g., Heart / Sixteen / Cookie, and they are asked to come up with a new word that links the three words together (If you want to give it a try, follow this link). Participants in this study first worked on the Remote Associates Test and then completed in an analogy task (e.g., Chips : Salty – Candy : S_ _ _ _ _). The purpose of this analogy task was to activate appropriate words that may become useful when taking the Remote Associated Test again. In the example above, activating the word “Sweet” can help generating it later when trying to find the one word that links “Heart”, “Sixteen” and “Cookie” together. After doing the analogy task, half of the participants took a 90-minute nap whereas the other half stayed awake. Afterwards, all participants retook the Remote Associates Test. It turned out that participants who had slept during the 90-minute interval were particularly successful in using information that they generated during the analogy task to solve items in the Remote Associates Test. In addition, the researchers found that a good amount of Rapid Eye Movement sleep – the sleep phase where dreaming occurs – was crucial for integrating previously encountered information in order to solve problems creatively.
Thus, it seems that creative solutions to problems can be enhanced through sleep. Ritter, Strick, Bos, van Baaren, and Dijksterhuis (5) went one step further and explored whether this effect can be further enhanced. In their experiment, participants engaged in the “Unusual Uses Task” which requires them to come up with as many creative solutions to a problem as possible. In the first step of the study, participants came to the lab in the evening and watched a video clip introducing the problem to them which was “how to motivate people to participate in volunteer work”. While watching the clip, a vanilla scent was sprayed in the room. All participants were sent home with an envelope and asked to open it before going to bed. The envelope contained a reminder of the creativity task that would happen the following morning and a scent diffuser. One group received a scent diffuser featuring the same vanilla scent, a second group received a scent diffuser featuring a different scent, and a third group did not receive a scent diffuser (control group). Participants who received a scent diffuser were asked to position it in close proximity to their bed. The next morning, all participants had to list as many creative solutions to the problem as possible. Ritter et al. found that participants who had been exposed to the same scent during sleep and encoding of the problem (i.e., while watching the video clip introducing the problem) came up with more creative solutions than participants who had been exposed with a different scent during sleep than during encoding or participants in the control condition. Thus, the mere exposure of the scent that was experienced when learning about the task in the first place triggered creative problem solving during sleep that benefitted later performance in the task. The authors conclude that “we do not have to passively wait until we are hit by our creative muse while sleeping [instead] we may be able to actively trigger creativity-related processes during sleep” (p. 646).
Taken together, a good night’s sleep or even a nap can improve our ability to solve problems in an efficient and creative way. If you are working on a hard problem and have reached an obstacle that seems insuperable, spend some time away from it and for the maximum effect: Sleep on it! You may be surprised with the solutions you can come up with.
(1) Metcalfe, J., & Wiebe, D. (1987). Intuition in insight and noninsight problem solving. Memory & Cognition, 15, 238-246.
(2) Beijamini, F., Pereira, S.I., Cini, F.A., & Louzada, F.M. (2014). After being challenged by a video game problem, sleep increases the chance to solve it. PLoS One, 9, e84342.
(3) Wagner, U., Gais, S., Haider, H., Verleger, R., & Born, J. (2004). Sleep inspires insight. Nature, 427, 352-355.
(4) Cai, D.J., Mednick, S. A., Harrison, E. M., Kanady, J. C., & Mednick, S. C. (2009). REM, not incubation, improves creativity by priming associative networks. Proceedings of the National Academy of Sciences, 106, 10130-10134.
(5) Ritter, S.M., Strick, M., Bos, M.W., van Baaren, R.B., & Dijksterhuis, A. (2012). Good morning creativity: task reactivation during sleep enhances beneficial effect of sleep on creative performance. Journal of Sleep Research, 21, 643-647.