SLEEP ONSET ENHANCES NOVEL IDEA GENERATION VIA FLEXIBLE MEMORY RECOMBINATION

While sleep may enhance creativity, the behavioural and neural mechanisms remain unclear. Divergent thinking, a core component of creativity, relies on associative recombination, through which existing memory elements are reorganized into novel configurations. Sleep onset (wake-to-N1 transition) is often accompanied by vivid but counterfactual visual imagery. Accordingly, we hypothesize that the wake-to-N1 transition enhances novel idea generation by enabling the flexible recombination of recently experienced memory elements. We tested this by developing a novel behavioural paradigm, the Associative Imagination Task (AIT), in which participants generated as many new ideas as possible from combinations of two elements belonging to different visual modalities (e.g., colour and texture). Sixty-two adults (Sleep: N = 30; Wake: N = 32) performed the AIT twice. For the Sleep group, the task session was separated by a morning nap with simultaneous EEG-fMRI recording; the Wake group remained awake and engaged in unrelated cognitive tasks. Behaviourally, the Sleep group generated significantly more novel ideas than the Wake group. Importantly, this improvement was specific to novel associations formed from pre-exposed visual elements. fMRI analyses showed that enhanced activity in the right anterior prefrontal cortex (R aPFC) and right pars opercularis of the inferior frontal gyrus (R IFG) during the wake-to-N1 transition predicted this behavioural facilitation. Furthermore, the aPFC decorrelated spontaneous activity in visual cortical regions encoding the pre-exposed visual elements, supporting the flexible recombination of distant concepts. Overall, our results implicate the aPFC and IFG in supporting novel idea generation triggered by brain state change during the wake-to-N1 transition.