The joint association between sleep quality, moderate-to-vigorous physical activity, cardiorespiratory fitness, and working memory in Chinese adolescents.

Background: Poor sleep quality is a prevalent health concern among Chinese adolescents. Although significant focus has been given to the impact of sleep problems on cognitive function, research on the association between sleep quality and working memory in typically developing adolescents remains limited. The aim of this study is to examine this association in Chinese adolescents.

Methods: The present study randomly recruited 2428 adolescents aged 12-18 years from four schools in Shanghai and Suzhou, eastern China in 2023 through two-stage cluster sampling. Information on sleep quality was collected using the questionnaire (Pittsburgh Sleep Quality Index). Adolescents' working memory was evaluated using the N-back task. A general linear regression analysis was conducted to evaluate the association between sleep quality and working memory, adjusted for potential confounders. Interaction terms, representing the product of sleep quality and each modifier, were included to test for interaction effects.

Results: In the adjusted model, adolescents with good sleep quality served as the reference group. Those with poor sleep quality had increased reaction times by 0.11 s (95%CI:0.09-0.13) during the 1-back task and by 0.10 s (95%CI:0.08-0.12) during the 2-back task. Moderate-to-vigorous physical activity (MVPA) time, cardiorespiratory fitness (CRF) and age significantly modified the associations between sleep quality and working memory (P for interaction < 0.05).

Conclusions: Chinese Adolescents with poor sleep quality exhibited poorer working memory, particularly among those who were younger, had insufficient MVPA time, and lower CRF. Good sleep quality is significant in improving cognition function among Chinese adolescents.