Abstract
Background
Adolescent sleep disturbances are a growing public health concern linked to mental health problems, including self-harm and suicidal ideation. However, most studies are cross-sectional, limiting understanding of temporal relationships. We examined the longitudinal association between sleep during adolescence and subsequent self-harm and/or suicidal ideation.
Methods
Data were drawn from the STARS cohort in Western Sweden at ages 13, 15, and 18 (n = 1,243, 62.5% females). Sleep duration, insufficient sleep, and sleep onset difficulties (SOD) were assessed at all time points; self-harm and suicidal ideation at age 18. Generalised estimating equations and generalised linear models analysed repeated sleep measures by outcome groups, while logistic and multinomial regression examined associations, adjusting for sex, immigrant background and parental education.
Results
School-day sleep duration declined (8.6, 8.0 and 7.6 hours at ages 13, 15, and 18), while insufficient sleep increased (12.9%, 34.0% and 51.8%). SOD also increased (19.1%, 22.0% and 25.3%) and was more common in females, who had shorter duration and more insufficient sleep at ages 13 and 15 (not 18). A higher proportion of females than males reported self-harm and suicidal ideation. Longer sleep duration at age 15 (not 13) was associated with lower odds of self-harm [OR (95%CI): 0.62 (0.52-0.74)] and suicidal ideation [0.58 (0.49-0.69)]. Insufficient sleep at age 15 (not 13) was associated with higher odds of self-harm [2.00 (1.47-2.74)] and suicidal ideation [2.38 (1.72-3.29)]. SOD at ages 13 and 15 were associated with higher odds of self-harm (age 13: [2.60 (1.82-3.71)]; age 15: [1.80 (1.27-2.56)] and suicidal ideation (age 13: [2.39 (1.65-3.44)]; age 15: [2.49 (1.75-3.56)].
Conclusions
Worsening sleep during mid-adolescence predicted later self-harm and suicidal ideation, highlighting sleep quality and duration as modifiable targets for early population-level interventions.
Key messages
• Worsening sleep during mid-adolescence predicted later self-harm and suicidal ideation.
• Sleep quality and duration are pivotal as modifiable targets for early interventions.