Bedtime social media use is associated with poor sleep during adolescence, which in turn contributes to poor mental health, impaired daytime functioning and lower academic achievement. However, the underlying drivers for these bedtime social media habits remain understudied. This study adds an adolescent perspective on motivations for bedtime social media use and perceived impact on sleep.Adolescents aged 11-17 years (n = 24) participated in focus group discussions exploring their experiences of using social media, particularly at night. Inductive reflexive thematic analysis produced themes that captured underlying drivers for social media use and associated impact on sleep.Our analyses produced two overarching themes: Missing Out and Norms & Expectations. Adolescents' nighttime social media use was driven by concerns over negative consequences for real-world relationships if they disconnected (often reporting delayed bedtimes, insufficient sleep and daytime tiredness). These concerns included the risk of offline peer exclusion from missing out on online interactions, and the fear of social disapproval from violating norms around online availability and prompt responses.These findings offer novel insight into why adolescents may choose to prioritize social media over sleep. Researchers and practitioners can respond to the evolving needs of today's adolescents by approaching social media use not as a technology-based activity, but as an embedded social experience underpinned by the same concerns as offline interactions.