Sleep Disturbances, Chronotype Characteristics, and Urinary 6-hydroxymelatonin Sulfate Levels in Adolescents with Suicidal Behavior and Non-suicidal Self-injury: A Case-control Study

Objective: Sleep disturbances and circadian dysregulation are implicated in adolescent self-harming behaviors.This study compared sleep disturbances, chronotype, and urinary 6-hydroxymelatonin sulfate (6-OHMS) levels among adolescents with suicidal behavior (SB), non-suicidal self-injury (NSSI), and healthy controls (HC).Methods: This cross-sectional case-control study included 120 adolescents aged 12-18 years (SB = 40, NSSI = 40, HC = 40).Diagnoses were established using Kiddie Schedule for Affective Disorders and Schizophrenia for School-Aged Children-Present and Lifetime Version for DSM-5.Sleep disturbances were assessed with Sleep Disturbance Scale for Children (SDSC), chronotype with Children's Chronotype Questionnaire (CCTQ), and melatonin secretion through 24-hour urinary 6-OHMS measurements.Group comparisons, covariance analyses, and correlation analyses were performed.Results: Total SDSC scores differed significantly among groups (p ＜ 0.001), with SB and NSSI showing greater sleep disturbances than HC.Significant differences were found in Disorders of Initiating and Maintaining Sleep, Sleep-Wake Transition Disorders, excessive somnolence, and arousal disorders.Although categorical chronotype distributions did not differ significantly, CCTQ scores were higher in NSSI than HC (p = 0.018).Urinary 6-OHMS levels did not significantly differ among groups (p = 0.091).Lower 6-OHMS levels were observed in the combined clinical sample than controls, but this association was not significant after adjustment for age, sex, and body mass index (p = 0.055).Chronotype scores were positively correlated with sleep disturbance severity.Conclusion: Adolescents with SB and NSSI demonstrated substantial sleep disturbances, while those with NSSI showed greater eveningness.Although urinary 6-OHMS levels did not significantly differentiate groups, the findings support a role of sleep and circadian processes in adolescent self-harm and warrant longitudinal investigation.