Effects of sleep timing, sleep quality and sleep duration on school achievement in adolescents

• The effects of sleep timing on school achievement in adolescents were explored.
• The effects of sleep quality and sleep duration were also analyzed.
• Morningness (ideal sleep timing) was positively correlated to the actual grade.
• Sleep efficiency (objective sleep quality) was positively correlated with the grade.
• At multiple regression analysis, sleep efficiency was the only predictor of grade.

ObjectiveThe aim of this study was to examine the effects of sleep timing, quality and duration on school achievement in adolescents.MethodsThirty-six Italian students (mean age: 18.14 ± 0.49 years) attending their last year of high school participated in the study. They completed the Morningness–Eveningness Questionnaire for Children and Adolescents (MEQ-CA). This was used to determine their ideal sleep timing by computing the total score, with higher scores corresponding to a greater tendency toward morningness. In addition, students underwent two non-consecutive weeks of actigraphy in one-month period to objectively assess: habitual sleep timing through the midpoint of sleep (MS); habitual sleep quality through the parameter of sleep efficiency (SE); and habitual sleep duration through the parameter of total sleep time (TST). Participants also completed the Mini Sleep Questionnaire, which allowed us to assess perceived sleep quality, at the end of each actigraphic-recording week. School performance was assessed using the grades obtained by students in their school leaving exams taken at the end of the school year.ResultsA significant positive correlation was observed between SE and exam grades, as well as MEQ-CA scores and grades. Multiple regression analysis showed that only SE was significantly and positively related to the final grade.ConclusionsExamining objective and ecological measures, SE (indicator of sleep quality) had the strongest effect on school achievement in adolescents.