Sleep and Circadian Timing Irregularities as Short-term Risk Factors for Adolescent Suicide: An Intensive Longitudinal Study

/ABSTRACT Suicide is a leading cause of death among adolescents, and rates of suicide in this age group have nearly doubled over the past two decades. However, our ability to predict and prevent suicidal thoughts and behaviors (STB) is limited, in part due to an emphasis on static, distal risk factors. Emerging research suggests that irregularities in sleep and circadian rhythms—systems which undergo marked change during adolescence— may be promising short-term predictors of suicide risk. However, prior studies have largely relied on retrospective self-report measures, long follow-up intervals, and have often overlooked the contribution of the circadian system, which collectively limits insight into the mechanisms underlying these dynamic processes that may increase suicide risk. This K23 project aims to address these gaps by leveraging intensive longitudinal methods, including actigraphy and collecting a biological indicator of endogenous circadian rhythms in a clinically acute adolescent sample. The proposed study will recruit 100 adolescents hospitalized for STB. During hospitalization, participants will continuously wear wrist actigraphs to measure objective sleep metrics (e.g., total sleep time, sleep onset latency) and provide continuous urine samples to estimate endogenous circadian timing using 6-sulfatoxymelatonin (aMT6s), a reliable indicator of circadian timing. Participants will also complete ecological momentary assessments (EMA) of suicidal ideation throughout their inpatient stay. STB will be reassessed at 1 and 3 months post-discharge, a period of heightened suicide risk. Three aims guide the project: (1) to test whether night-to-night variations in sleep predict next-day SI during hospitalization and STB after discharge; (2) to evaluate whether later circadian timing is associated with higher SI during hospitalization, increased risk for STB post-discharge, and shifts in the timing of SI toward later hours; and (3) to examine whether greater circadian misalignment—i.e., discrepancies between sleep behaviors and the biological clock—predicts increased STB both during hospitalization and after discharge. The proposed training plan complements the Candidate's research plan and will provide the Candidate with rigorous training in actigraphy, biological measurement of circadian rhythms, and advanced longitudinal data analysis. A team of leading scholars will provide expert mentorship in the assessment of adolescent suicide, sleep and circadian biology, and, intensive longitudinal methods, and biostatistics. The project is embedded in a rich, interdisciplinary research environment at Massachusetts General Hospital. By identifying modifiable, objective markers of short-term suicide risk, this research has the potential to advance predictive models and inform clinical interventions, particularly chronotherapeutic approaches. The proposed study will promote the Candidate's long-term goal of establishing an independent program of research focused on leveraging sleep and circadian science to improve youth mental health and reduce STB. Project Number: 1K23MH144215-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Mental Health (NIMH) | Principal Investigator: Rachel Walsh | Institution: MASSACHUSETTS GENERAL HOSPITAL, BOSTON, MA | Award Amount: $197,578 | Activity Code: K23 | Study Section: Special Emphasis Panel[ZRG1 SCIL-X (90)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11350523