Adolescence is often characterised by changes in sleep patterns, with reports that the average adolescent does not get the recommended sleep time. Recent qualitative research has identified the use of electronics at bedtime and engagement with social media platforms as barriers to gaining sufficient time and quality of sleep during adolescence. A systematic review and thematic synthesis was undertaken following the three-step thematic synthesis framework. Four databases were searched, and full texts were screened based on pre-existing inclusion/exclusion criteria. Fourteen studies were included, encompassing 967 participants. Three analytical themes were developed: 1) social motivations; 2) habitual smartphone use and 3) recognition of a problem. Findings confirmed how bedtime social media use requires a new framework for recognising the importance of peer relations, where increased frequency and immediacy of communication lays the foundation for social accountability to meet communicative norms and fear of missing out. In the review, adolescents commonly express a lack of control in relation to their social media use which triggered discussion of the habitual aspects of bedtime social media use. The importance of intervention strategies which recognise the wider peer-to-peer social implications of bedtime social media use is discussed with some practical insights offered.