Original ArticleLate bedtimes weaken school performance and predispose adolescents to health hazards

Study objectivesOur study explored if bedtimes influenced school performance and motivation, as well as the odds ratio (OR) for health-related concerns in adolescents.MethodsThe School Health Promotion Study was based on an anonymous self-report questionnaire conducted in 90% of the municipalities in Finland. The study was conducted during 2008 and 2010 in Southern Finland, Eastern Finland, and Lapland, and during 2009 and 2011 in Western Finland, Northern Finland, and Åland. Several indicators were used to measure school performance and motivation. Accidents and health-related complaints, such as depressive symptoms, sleep quality, neck or shoulder pains, lower back pains, stomachaches, anxiety or nervousness, irritation or tantrums, headaches, and tiredness or dizziness were analyzed in relation to the usual bedtime. Our study had a relatively large sample size (N = 384,076), consisting of students in the eighth and the ninth grades of secondary schools and the first and the second grades of upper secondary and vocational schools (ages 14-20 years) in Finland.ResultsAll of the various indicators used to assess school performance and motivation suggest that the later the bedtime of adolescents, the lower their school performance and their motivation. Similarly later bedtimes increase the OR for depressive symptoms and other negative health consequences in adolescents as well as a tendency towards accidents. All of these problems were emphasized in students with bedtimes of 11:30 PM and later.ConclusionsLate bedtimes, especially those after 11:30 PM, indicate poor sleep which deteriorates school performance and motivation and increases the OR for depressive symptoms and other health-related issues in adolescents.