Background: Sleep is essential for overall health and plays an important role for the mental and physical development of adolescents. The increase in sleep problems during adolescence coincides with rising levels of mental health problems, such as depression and suicidality. Improving the understanding of the relationship between adolescents’ sleep and mental health could inform the development of preventive interventions and clinical treatments. The aim of this study was to investigate the relationship between different sleep parameters and depression, as well as suicidal ideation, in a large sample of adolescents.
Methods: Questionnaire data were obtained from a representative sample of Swedish adolescents (n=10288; 50.3% boys; aged 12-16). Sleep parameters were assessed by a validated sleep measurement instrument, the Karolinska Sleep Questionnaire (KSQ). Depression was defined as >13 BDI-II scores. Suicidal ideation was defined as seriously considering or planning for attempting suicide during the previous two weeks, measured through an item from the Paykel scale. Logistic regression was used to estimate the effects of sleep duration, sleep quality, and chronotype on depression (n=8449) as well as suicidal ideation (n=4433).
Results: A large proportion of Swedish adolescents (46%) did not meet the recommendation of 8 hours sleep per night on weekdays. Weekday sleep duration was shorter in adolescents with depression (M=7:11h compared to M=8:04h) and suicidal ideation (M=6:54h compared to M=7:54h). Shorter weekday sleep duration was associated with depression (OR=0.773, p<.0001) and suicidal ideation (OR=0.759, p<.0001). Late chronotype was associated with depression (OR=1.126, p=.0017). Sleep quality had the strongest effect and was associated with both depression (OR=0.327, p<.0001) and suicidal ideation (OR=0.524, p<.0001). The effects of sleep duration and sleep quality on suicidal ideation remained even after adjusting for the effect of depression.