How Memory Replay in Sleep Boosts Creative Problem-Solving

Creative thought relies on the reorganisation of existing knowledge. Sleep is known to be important for creative thinking, but there is a debate about which sleep stage is most relevant, and why. We address this issue by proposing that rapid eye movement sleep, or ‘REM’, and non-REM sleep facilitate creativity in different ways. Memory replay mechanisms in non-REM can abstract rules from corpuses of learned information, while replay in REM may promote novel associations. We propose that the iterative interleaving of REM and non-REM across a night boosts the formation of complex knowledge frameworks, and allows these frameworks to be restructured, thus facilitating creative thought. We outline a hypothetical computational model which will allow explicit testing of these hypotheses. It is commonly accepted that sleep promotes creative problem-solving, but there is debate about the role of rapid eye movement (REM) versus non-REM sleep. Behavioural evidence increasingly suggests that memory replay in non-REM sleep is critical for abstracting gist information (e.g., the overarching rules that define a set of related memories). The high excitation, plasticity, and connectivity of REM sleep provide an ideal setting for the formation of novel, unexpected, connections within existing cortically coded knowledge. The synergistic interleaving of REM and non-REM sleep may promote complex analogical problem solving.