Maartje Boer

INTRODUCTION 17 1 In Which Direction Are SMU Intensity and SMU Problems Related to Lower Wellbeing? Another shortcoming of previous research is that they do not show whether lower wellbeing precedes from or follows after higher levels of SMU intensity or SMU problems, either because they largely used cross-sectional data, or longitudinal analysis that did not explore directionality (Bányai et al., 2017; Kelly et al., 2018; Shensa et al., 2017; Van den Eijnden et al., 2018). Theoretically, SMU intensity and SMU problems could both be causes as well as consequences of lower wellbeing. For example, as highlighted above, SMU may increase adolescents’ ADHD-symptoms. Or, it may increase depressive symptoms, whereby upward social comparisons, displacement of schoolwork activities or face-to-face contacts, or cybervictimization possibly play a mediating role (Pera, 2018; Underwood & Ehrenreich, 2017; Verduyn et al., 2020). However, as mentioned earlier, such effects on wellbeing may rather be driven by adolescents’ SMU problems than by their SMU intensity (Shensa et al., 2017; Van den Eijnden et al., 2018). A reverse order, whereby lower wellbeing causes higher levels of SMU intensity or SMU problems, also seems plausible. For example, given that adolescents with ADHD-symptoms are typically sensitive to external distractors (American Psychiatric Association, 2013), they may have a limited ability to forego incoming notifications and messages through social media smartphone applications, and consequently they may often not be able to resist temptations to use social media. Or, adolescents with depressive symptoms may use social media intensively or become dependent on it to cope with or escape from their negative feelings, or to feel more positive about themselves (Caplan, 2003; Griffiths, 2013). It is unclear whether these aspects of lower wellbeing could reinforce high SMU intensity, SMU problems, or both. Establishing the potential causal order of the relation between adolescents’ SMU behaviors and specific aspects of their wellbeing enhances current theoretical knowledge on the emergence as well as potential impact of high SMU intensity and SMU problems. In doing so, disentangling SMU intensity and SMU problems in their association with wellbeing is considered important, because this identifies which particular SMU behavior precedes or follows frompoorer wellbeing. Furthermore, distinguishing between different