Monitoring Within-Person Dynamics in Adolescents Hospitalized for Acute Suicidal Distress: Protocol for an Intensive Longitudinal Study

BackgroundAdolescence represents a developmental period marked by heightened vulnerability to suicidal thoughts and behaviors (STBs), which remain a leading cause of death among youth, particularly psychiatric inpatients and after discharge. Contemporary ideation-to-action models conceptualize suicidal crises as dynamic processes driven by proximal psychological factors rather than static risk markers. While recent work has begun to examine these processes as they unfold in daily life, their integration into the clinical course of suicidal distress remains limited. In this perspective, relating short-term micro-level processes of STBs to their broader temporal changes across the transition of adolescents from acute inpatient hospitalization to early ambulatory aftercare constitutes an important area for further investigation.ObjectivesThis protocol describes a multimodal, intensive longitudinal study examining the temporal unfolding of suicidal distress across complementary timescales. The integrative framework aims to identify prototypical trajectories of STBs from inpatient admission through early post-discharge. It further seeks to characterize heterogeneity in within-person processes central to ideation-to-action theories and STB-related affect regulation. Finally, the study aims to interrelate these micro-level dynamics of suicidal distress with its longitudinal trajectories on the macro-level. Within this framework, the study examines how modifiable bioregulatory factors, including sleep and physical activity, as well as clinical process factors such as therapeutic alliance, are dynamically implicated across timescales.MethodsThe study plans to recruit 100 adolescents hospitalized from a single site in French-speaking Switzerland. Within 72h upon admission, participants start a first ambulatory assessment period of up to 14 days, comprising with 4 daily Ecological Momentary Assessment (EMA) surveys and continuous actigraphy recordings. A second assessment period follows participants from discharge over the following 10 days and includes 2 daily EMA surveys. In addition, 4 in-person assessment sessions contextualize the intensive longitudinal time-series with baseline clinical characteristics, diagnostic status, therapeutic processes, and episodic stressors. Planned analyses will use multilevel and latent class modeling approaches to identify longitudinal patterns of STBs, characterize between-person differences in within-person dynamics, and examine how these patterns relate to contextual factors. ResultsRecruitment began in October 2025 and is expected to continue until spring 2028. The protocol was developed by actively the perspectives of former patients and the lived experience of clinicians. Feedback from the first five participants supported maintaining the initial implementation of the protocol.ConclusionsBy focusing on the link between intraindividual short-term ...