Youth Suicide and Self-Harm Intervention: Clinical and Biological Outcomes Study

The goal of this clinical trial is to develop and evaluate youth-focused intervention programs for suicide and self-harm that are tailored to the psychological, developmental, and cultural characteristics of Korean adolescents and young adults. The study examines whether two structured, mindfulness-based intervention programs-one for middle and high school students and one for young adults-reduce suicidal ideation, self-harm behaviors, depressive symptoms, and emotion-regulation difficulties. The study also aims to determine whether these clinical improvements are associated with biological changes, including alterations in resting-state functional brain activity (e.g., ALFF, ReHo, and functional connectivity) and social rhythm patterns. The main questions this study seeks to answer are: * Does the youth suicide and self-harm intervention program reduce suicidal ideation and self-injurious thoughts/behaviors? * Does the program improve mood, sleep, hopelessness, and emotion regulation? * Are improvements in clinical outcomes accompanied by changes in biological markers of suicide risk? * Researchers will compare the intervention program to usual care provided in hospitals, schools, and community mental health settings. Participants will: * Participate in the structured suicide/self-harm intervention program or receive usual care. * Complete standardized assessments of mood, sleep, emotion regulation and suicide/self-harm risk. * Undergo biological assessments, including resting-state fMRI and rhythm-related measures, at baseline and follow-up. * Be followed for up to 12 weeks.