Associations between sleep duration, insomnia, depression, anxiety and registry-based school grades: A longitudinal study among high-school students.

This study explored the prospective associations between sleep patterns, mental health and registry-based school grades among older adolescents. In the spring of 2019, 1st year high-school students in Western Norway were invited to a survey assessing habitual sleep duration, insomnia, depression and anxiety. Sleep patterns, depression and anxiety were assessed using the Munich ChronoType Questionnaire, the Bergen Insomnia Scale, the Patient Health Questionnaire-9, and the Generalized Anxiety Disorder-7. Students consenting to data linkage with the county school authorities were re-invited 2 years later. Registry-based grade point averages for each of the included school years were accessed through the school authorities. The final longitudinal sample included 1092 students (65.1% girls; initial mean age 16.4 years). Data were analysed using linear mixed models. Longer school night sleep duration and less severe symptoms of insomnia, depression and anxiety were all associated with higher grade point averages at baseline in crude analyses. Shorter school night sleep duration, as well as more severe symptoms of insomnia and depression at baseline, all predicted better grade point averages at 2-year follow-up when controlled for baseline grade point averages. By contrast, anxiety symptomatology at baseline was unrelated to changes in grade point averages over time. The longitudinal associations between school night sleep duration and insomnia symptoms on grade point averages were significant also when adjusted for sex and baseline symptoms of depression and anxiety. These findings indicate that shorter school night sleep duration and more severe insomnia symptoms predict lower grade point averages development over time, irrespective of co-existing symptoms of depression and anxiety.