0055 Leptin Moderates the Relationship Between Sleep Quality and Memory Function: A Population-based Study

Abstract Introduction Sleep is crucial for memory, as it promotes its encoding, consolidation, storage, and retrieval. Sleep periods following learning enhance memory consolidation. Leptin, a hormone that regulates appetite and energy balance, also influences memory and neuroplasticity. It plays a neurotrophic role in the hippocampus, enhancing synaptic function and promoting memory processes. Given these associations between sleep, memory, and leptin, this study aimed to evaluate the interplay between sleep quality, memory complaints and leptin levels. Methods Using data from the São Paulo Epidemiologic Sleep Study (EPISONO) 2007 edition, we analyzed data from 881 participants who underwent evaluations for subjective sleep quality (Pittsburgh Sleep Quality Index), memory function (Prospective and Retrospective Memory Questionnaire), body mass index and plasmatic leptin levels. Linear regression explored variable relationships, and a mediation/moderation model assessed causal effects on sleep quality, memory, and leptin, with age as a covariate. Analyses were performed on all volunteers and separately by sleep quality, considering sex as a potential influence. The statistical software used was Jamovi version 2.3.24, with a significance level set at 5% (p< 0.05). Results After confirming that subjects with poor sleep quality had more memory complaints (p< 0.001) in our cohort, we observed that leptin levels were increased in individuals with more memory complaints (p< 0.001) but there was no association between leptin levels and sleep quality (p=0.177). Mediation analysis reinforced the direct effect of sleep quality on memory function, but leptin had no indirect effect as mediator over the sleep-memory association. Moderation analysis revealed that leptin acted as a moderator in the relationship between sleep quality and memory (p< 0.001), with increased leptin levels enhancing the effect of sleep quality over memory function. Conclusion Leptin, a hormone involved in appetite control and energy balance, acts as a moderator of the relationship between sleep quality and memory performance. Individuals with high leptin levels are more susceptible to the negative effects of poor sleep on memory. This finding highlights the complexity of the interaction between sleep, memory, and metabolic factors, such as leptin, and its potential implications for overall health and well-being. Support (if any) AFIP, FAPESP, CNPq.