Abstract Background Social media (SOME) use has been linked to psychological problems in some studies, but the results are mixed. Digital stress may explain the link between SOME and mental health, but the underlying components that constitute the subjective stress experience that may stem from SOME use remain uncertain. Different conceptualizations of digital stress have been proposed, and frequent suggestions include aspects of availability stress, approval anxiety, fear of missing out (FOMO) and time-wasting. Method A survey was conducted with 3568 students (62% girls) at upper secondary schools, to explore potential underlying components related to SOME as a perceived stressor among Norwegian adolescents. The study used linear regression models to analyze predictors of SOME as a stressor, grouped into two main composite measures: ‘FOMO and affected by use’ and ‘Addiction and interference'. In a nested longitudinal sample (n = 432), a first-differencing model was estimated to test the longitudinal associations between the factors and SOME as a perceived stressor. Results SOME was perceived as a stressor at least sometimes for 31 % of the adolescents, with 16 % for girls and 6 % of boys reporting SOME as a considerable stressor. Collectively, ‘FOMO and affected by use’ and ‘Addiction and interference’ explained 38% of the variance SOME as a perceived stressor. In longitudinal analyses, a one unit increase in the composite score ‘FOMO and affected by use’ yielded a 0.52 (p < 0.001) standard deviation increase in SOME as a perceived stressor, while the corresponding estimate was 0.30 (p < 0.001) for ‘Addiction and interference'. Conclusions Our findings highlight important aspects of SOME use that may underlie the subjective stress experience - both in cross-sectional and longitudinal analyses. Our results are consistent with previous findings and indicate that those aspects are important targets for action for both girls and boys. Key messages • Our study sheds light on the components that contribute to social media as a perceived stressor among adolescents, highlighting important targets for action. • The findings suggest that fear of missing out, affected by use, subjective addiction and interference are significant predictors of social media stress, with implications for both girls and boys.