Researchers propose how REM and non-REM sleep may work together to help us solve problems

Sleep is known to be important for creative thinking, but exactly how it helps and what role each sleep stage–REM and non-REM–plays remains unclear. A team of researchers have now developed a hypothesis, outlined in an Opinion published May 15 in the journal Trends in Cognitive Sciences, to explain how the interleaving of REM and non-REM sleep might facilitate creative problem solving in different but complementary ways.


Studies show that this kind of restructuring often happens while we are asleep, so Lewis and her co-authors drew on that literature, as well as physiological and behavioral data, to create a model of what might be happening during each stage. Their model proposes that non-REM sleep helps us organize information into useful categories, whereas REM helps us see beyond those categories to discover unexpected connections.


During REM sleep, on the other hand, the hippocampus and cortex don't appear to be nearly as in sync. So, Lewis's team suspects that the cortex is now free to replay stored memories in any combination, regardless of whether they are similar. Meanwhile, evidence suggests that ponto-geniculo-occipital waves cause areas of the cortex to randomly activate, which could trigger the replay of memories from different schemas.


To illustrate, she refers to Earnest Rutherford's discovery of the structure of an atom. He based his design on something that might seem unrelated: the solar system. According to the model that Lewis and her team propose, Rutherford's knowledge of atoms and solar systems would have been categorized into different schemas during non-REM sleep. Then, during REM sleep, his memories of atoms could have been replayed along with a randomly activated memory of the solar system, allowing him to detect the overlap between them and, later, apply it to his work.



The authors are supported by the European Research Council, EPSRC, Cardiff University, UCLA, and the National Institutes of Health.

Trends in Cognitive Sciences, Lewis et al.: "How memory replay in sleep boosts creative problem solving"

Trends in Cognitive Sciences (@TrendsCognSci), published by Cell Press, is a monthly review journal that brings together research in psychology, artificial intelligence, linguistics, philosophy, computer science, and neuroscience. It provides a platform for the interaction of these disciplines and the evolution of cognitive science as an independent field of study. Visit: To receive Cell Press media alerts, please contact [email protected]

Media Contact

Kelly McClorey
[email protected]