Early bird catches the worm? The relation between school schedule, sleep quality, and depression in Croatian adolescents

Sleep problems and depression increase in adolescence. Adolescents tend to go to sleep at a later time, which results in shorter sleep duration especially if they attend school in the morning. The aim of this study was to examine the relation between school schedule (morning school schedule and afternoon school schedule), sleep quality, and depression in Croatian adolescents. A total of 253 students of third and fourth grades of high school (17 and 18 years of age) completed measures of sleep quality and depression. Results have shown that participants who attend school in the morning also sleep less, have more difficulties in daily functioning due to problem with sleep and are more depressed, but their habitual sleep efficiency is better than in participants who attend school in the afternoon. Furthermore, depression was correlated with poorer sleep latency, sleep duration, more sleep disturbances, use of sleep medication, daytime dysfunction, as well as poorer global sleep quality index. Finally, morning school schedule, poorer sleep duration, sleep disturbances, use of sleep medication, and daytime dysfunction predicted depression, with sleep duration and daytime dysfunction mediating the relation between school schedule and depression.