LAUSR

Adolescents’ daily lives have been disrupted during the Coronavirus disease 2019 (COVID‐19) pandemic. It remains unclear how changes in adolescents’ daily physical and social behaviours affect their sleep. The present study examined the daily and average effects of physical activity and social media use (i.e., video chatting, texting, and social networking sites) on adolescent girls’ sleep during the COVID‐19 pandemic. Adolescent girls aged 12–17 years (N = 93; 69% White) from a larger longitudinal study completed a 10‐day daily diary protocol during state‐mandated stay‐at‐home orders. Girls reported on daily sleep (duration, timing, quality), physical activity, and social media use during COVID‐19. Multilevel modelling was used to examine the within‐ and between‐person effects of physical activity and social media on sleep duration, timing, and quality during the 10‐day period. Between‐person associations indicate that youth with greater social media use (texting, video chatting, and social networking) and less physical activity had later sleep timing across the 10‐day study period. Only video chatting was associated with shorter sleep duration. There were no within‐person effects of physical activity or social media activities on sleep outcomes. Findings indicate that physical activity and social media use may impact later adolescent sleep timing during the COVID‐19 pandemic. It will be critical for research to examine the potential long‐term costs of delayed sleep timing, and whether targeting specific youth behaviours associated with sleep and circadian disruption improve mental and physical health during the COVID‐19 pandemic and beyond.