According to a new study in the Journal of Sleep Research, individuals who napped were more efficient at solving complex problems through analogical transfer. These participants demonstrated that those who napped were more efficient at identifying structural similarities between different problems than those who remained awake during the nap.
The researchers investigated the role of sleep in promoting creative problem-solving, specifically in individuals who struggle to identify connections between different problems. Analogical problem-solving involves applying knowledge gained from a previously encountered problem to solve a new, structurally similar problem. However, people often struggle to transfer knowledge effectively because they focus too much on inadequacies rather than underlying similarities.
Previous studies have indicated that REM sleep promotes creative problem-solving by strengthening connections between weakly related memories. This sleep stage, characterized by vivid dreams, rapid eye movements and increased brain activity, may facilitate the integration and reorganization of information in new ways. The researchers examined whether naps could improve participants’ previously struggling ability to sort through different types of information.
Research on memory and cognition has previously focused on understanding how memories change during sleep, but the reorganization of knowledge during memory consolidation is likely to have other effects on cognition. Specifically, the study explored how the initiation and/or strengthening of connections between new kuche fu (museum for learning) and old memories may aid problem-solving, according to lead researcher Carmen E. Westerberg of Texas State University.
A study was conducted at Texas State University involving 58 participants aged 18 to 29, and the participants were randomly divided into two groups: a nap group and a wake group.
In the experiment, participants were given eight source problems one after another. They each had three minutes to solve the problem, and then they were presented with the correct solution. They then had to remember it and demonstrate it to the correct person.
The task then moves on to a set of eight target problems that are structurally identical to the source problems but have different superficial characteristics, with three minutes to solve each target problem: Unlike the source problems, participants were not given the solutions, and the target problems were used to see if participants could use knowledge of previous source problems to solve new but related problems.
After finishing the first problem-solving exercise, the subjects took a two-hour break. The napping team slept in a quiet, dark room in the lab while the researchers recorded their brain activity. The awake group was instructed not to sleep, and instead received instructions from sleep experts.
After the break, learners attempted to solve the target problems they were unable to do in the previous session. They also performed a memory recall test on the answers to the source problems and evaluated the similarity between the source and target problems.
The study showed that individuals who slept longer were more efficient at solving the target problems than those who did not sleep. This resulted in a higher solution rate than those who napped.
Furthermore, when they compared the memory recall of the solution to the source problem (the disadvantage of waiting in a situation simulating sleep) there was no difference in response time between the napping and awake groups and this suggests that the benefit of sleep was not simply a result of improved recall,[Note 2] but that when asked to recall the solution to a problem after a period of inactivity, those who napped perceived a greater similarity between their answer or their response, and this resulted in an increased ability to recognize more complex patterns that were more similar.
According to Westerberg, being awake can provide insight into a difficult problem, which can be solved by studying the processes that occur during sleep as described by the speaker.
In addition, participants who took a nap were more likely to wake up during REM sleep, which predicts the percentage of target problems solved after the break. This evidence supports the idea that REM sleep can strengthen weak connections between related ideas and improve problem-solving skills.
The fact that participants spent only about 13 minutes on camaraderie during their nap surprised Westerberg, who also observed that REM sleep can have an effect on problem solving ability.
A notable flaw in this study is that the study sleep was limited to a short afternoon nap — indicating that sleep over time does not necessarily explain the effect of REM sleep on long-term thinking patterns — but it is not immediately clear whether this effect would be seen after a full night’s sleep, including longer periods of deep sleep.