Speech-sound memory consolidation over a daytime nap in adults with and without developmental language disorder

Introduction Sleep plays a critical role in memory consolidation, yet its contribution to the formation of perceptual-linguistic representations remains only partially understood. In the current study, we examined sleep spindles and slow oscillations (SOs) in relation to offline changes in speech-sound memory in adults across a wide range of language ability. Methods Twenty-nine monolingual English-speaking participants completed a perceptual training task contrasting retroflex /ɖ/ and dental /d̪/ consonants, followed by a polysomnography-monitored nap. Results Slow spindle density was positively associated with perceptual discrimination performance following a nap, whereas slow oscillation (SO) density was negatively associated. SO-slow spindle coupling strength was significantly correlated with language difficulty amongst those with developmental language disorder, such that those with a lower synchronization index were observed with greater difficulties in language ability. Discussion Together, these findings point to the potential relationship between sleep and perceptual-linguistic representation, and developmental language disorder.