A recent study published in the Journal of Sleep Research provides evidence that sleep, particularly rapid eye movement (REM) sleep, enhances problem-solving ability through analogical transfer. The researchers found that participants who took a nap were more successful at solving complex problems after sleep than those who remained awake. This improvement appeared to result from the nap group’s increased ability to recognize structural similarities between different problems rather than improved memory of prior problems.
The researchers conducted this study to explore how sleep might enhance creative problem-solving, particularly when individuals struggle to recognize connections between different problems. Analogical problem-solving involves applying knowledge from a previously encountered problem to solve a new, structurally similar problem. However, people often fail to transfer knowledge effectively because they focus too much on superficial differences rather than underlying similarities.
Prior research suggests that REM sleep facilitates creative problem-solving by strengthening connections between weakly related memories. This sleep stage, characterized by vivid dreaming, rapid eye movements, and heightened brain activity, may help integrate and reorganize information in novel ways. The researchers tested this theory by investigating whether a nap could improve participants’ ability to solve problems they had previously struggled with.
“My previous research has focused on understanding how memories change during sleep. However, the reorganization of knowledge that occurs during memory consolidation undoubtedly impacts other aspects of cognition as well. I was specifically interested in how the initiation and/or strengthening of connections between new and old memories can assist in problem solving,” said study author Carmen E. Westerberg, a professor at Texas State University and head of the Cognitive Neuroscience Lab.
For their study, the researchers recruited 58 participants aged 18 to 29 from Texas State University and randomly assigned them to one of two groups: a nap group or a wake group.
At the start of the experiment, participants were presented with eight source problems, one at a time. Each problem was displayed on a screen, and participants had three minutes to attempt to solve it. Afterward, they were shown the correct solution and asked to remember it.
Next, they were presented with eight target problems, which were structurally similar to the source problems but had different surface features. Participants had three minutes to attempt to solve each target problem, but unlike the source problems, they were not shown the solutions. These target problems were used to assess whether participants could apply knowledge from the earlier source problems to solve new but related problems.
After these initial problem-solving tasks, participants took a two-hour break. The nap group slept in a quiet, dark room in the laboratory while researchers monitored their brain activity using electroencephalography. The wake group remained awake and was instructed not to sleep, use drugs, or consume alcohol.
At the end of the break, participants attempted to solve the target problems they had previously been unable to solve. They also completed a memory test to recall the solutions to the source problems and rated how similar they perceived the source and target problems to be.
The researchers found that participants who took a nap solved significantly more target problems after the break than those who remained awake. This effect was not due to differences in initial problem-solving ability, as both groups had similar solution rates before the break.
Additionally, the nap and wake groups did not differ in their ability to remember the source problem solutions, indicating that the benefit of sleep was not merely due to improved memory. Instead, participants who napped perceived greater similarity between source and target problems, suggesting that sleep helped them recognize deeper connections that were not initially apparent.
“The main takeaway is that if you have a difficult problem that you cannot solve, processes that occur while you are sleeping may give you insights after waking that could help to solve the problem,” Westerberg told PsyPost.
Furthermore, within the nap group, the amount of time spent in REM sleep predicted the proportion of target problems solved after the break. This finding suggests that REM sleep plays a key role in enhancing problem-solving ability by strengthening weak associations between related ideas.
“I was surprised that REM sleep specifically was implicated in increased problem solving, given that participants spent a relatively short amount of time in REM during their naps—approximately 13 minutes on average,” Westerberg remarked. “Apparently even small amounts of REM sleep can boost problem-solving ability.”
One limitation of the study is that sleep was restricted to a short afternoon nap, which may not fully reflect how sleep impacts problem-solving over a longer period. While the results suggest that REM sleep played a key role in improving analogical transfer, it remains unclear whether the same effect would be observed following a full night’s sleep, which includes longer durations of deep sleep stages.
“My long-term goals are to extend these findings to overnight sleep and to examine how REM sleep may contribute to other types of creative problem solving and decision-making,” Westerberg said.
The study, “An afternoon nap facilitates analogical transfer in creative problem solving”, was authored by Carmen E. Westerberg, Sean E. Fickle, Chloe E. Troupe, Anna Madden-Rusnak, and Rebecca G. Deason.
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