Using Real-Time Methods to Investigate Emotion Regulation as a Modifiable Target Connecting Adolescent Social Media Use and Mood - PROJECT SUMMARY/ABSTRACT Adolescent social media (SM) use is linked to adverse mental health outcomes (e.g., depression, anxiety, suicidal thoughts/behaviors) for some adolescents but not others. Adolescent rates of depression and suicidal thoughts and behaviors are steadily rising. In 2021, 42% of high school students reported persistent feelings of depression and hopelessness, and 10% attempted suicide. As SM may contribute to these staggering numbers, it is crucial to understand what separates positive from negative SM mental health outcomes among adolescent SM users. Emotion regulation is a modifiable factor and widely used clinical intervention target that may amplify or buffer against negative mental health outcomes resulting from adolescent SM use. For example, if an adolescent has a negative experience on SM, if they choose an adaptive emotion regulation strategy (e.g., reappraisal), they may decrease negative mood and ultimately not experience mental health consequences. On the other hand, if they repeatedly choose maladaptive strategies (e.g., avoidance, rumination), they could amplify their negative mood, increasing risk for developing mental health concerns (e.g., depression, suicidal thoughts/behaviors). To inform future intervention work targeting emotion regulation to maximize adolescent SM and mental health outcomes, this NRSA proposes to identify: 1) How adolescents regulate their emotions following negative SM experiences, 2) Which emotion regulation strategies amplify or buffer against negative mood following a negative SM experience, and 3) The specificity of these relationships to SM relative to other social contexts. This study will recruit 50 adolescents (age 14-17; grades 9-12). Participants will complete ecological momentary assessment (EMA) prompts 3x/day over the course of four weeks to measure 1) negative SM experiences, 2) emotion regulation strategy selection following each experience, and 3) mood. Passive smartphone sensing will additionally capture SM use behaviors. This study will build upon and extend the sponsor (Dr. Hamilton)’s K01 study (K01MH121584). Using this high-dimensional data, multilevel models will evaluate which emotion regulation strategies adolescents most commonly use following a negative SM experience, differential effectiveness of these emotion regulation strategies, and the specificity of these effects to SM relative to in-person social contexts. The immediate impact of this study will be to identify whether emotion regulation strategies have the potential to modify mood following a negative SM experience. More broadly, this study will inform clinical interventions targeting emotion regulation—a core element of many existing evidence-based treatments—to buffer against possible negative mental health effects of adolescent SM use.