The Impact of Napping and Sleep History on Perceptual Speech Learning and Memory Consolidation

This study examines the memory consolidation effects of a 90-minute nap on perceptual speech learning and explores the variability in consolidation outcomes related to individual differences in sleep history. Previous research shows that sleep facilitates the stabilization of memory, yet the role of sleep history and napping on cognitive performance remains less understood. We explored whether individuals with varying amounts of sleep the night before would benefit differentially from a nap in terms of memory consolidation and perceptual learning performances. In a sample of 53 participants, we employed a pretest-training-posttest design with synthetic speech recognition tasks. Subjects were randomly assigned to a nap or wake condition following morning training sessions. Performance was assessed across multiple posttests throughout the day, with a final session in the evening. Results indicated that while all participants demonstrated perceptual learning, those in the nap condition showed stabilized performance post-nap, consistent with the hypothesis that napping aids in memory consolidation. Conversely, the wake group experienced a decline in performance throughout the day, suggesting that napping can mitigate perceptual speech performance degradation over waking retention intervals. Importantly, a regression analysis revealed that longer sleep the night before the experiment correlated with less maintenance of learning in the wake group, whereas napping appeared to buffer this effect. This thesis provides novel insights into the complex interplay between sleep history and the cognitive benefits of napping. It suggests that even brief periods of sleep, such as naps, can positively impact memory consolidation, potentially offering cognitive benefits. These findings carry significant implications for optimizing learning and memory consolidation strategies.