Everyday Discrimination Alters Cognitive Benefits of Restorative NREM Sleep in Black Adults

Abstract Study Objectives Restorative non-rapid eye movement (NREM) sleep has been linked to cognitive functioning. Yet, it remains unclear whether experiences of discrimination, a persistent form of identity-based adversity, shape how objectively measured restorative NREM sleep relates to cognitive outcomes in Black Americans. Methods Ninety-two Black adults completed the Everyday Discrimination Scale, a cognitive assessment, and three nights of at-home sleep monitoring. Restorative NREM sleep was indexed using N2–N3 delta power. Moderation analyses evaluated whether everyday discrimination altered the association between restorative NREM sleep and global cognition, assessed with the Montreal Cognitive Assessment, as well as visuospatial memory, assessed with the Benson Complex Figure task, adjusting for age, sex, marital status, education, subjective socioeconomic status, BMI, and sleep efficiency. Results Discrimination moderated the relationship between restorative NREM sleep and global cognition. At lower levels of discrimination, greater level of restorative NREM sleep corresponded to higher global cognition scores, whereas at higher levels of discrimination, a greater level of restorative NREM sleep corresponded to lower global cognition scores. The interaction between restorative NREM sleep and discrimination on visuospatial memory was not significant after full covariate adjustment, with education emerging as a significant independent predictor of visuospatial memory. Conclusions The findings suggest that associations between restorative NREM sleep and global cognition vary across levels of everyday discrimination among Black adults, independent of socioeconomic and health-related factors. These results highlight discrimination as a relevant contextual factor to consider when examining sleep-cognition relationships in cognitive aging.