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

Objective: The aim of this study was to examine the effects of sleep timing, quality and duration on schoolachievement in adolescents.Methods: Thirty-six Italian students (mean age: 18.14 ± 0.49 years) attending their last year of high schoolparticipated in the study. They completed the Morningness–Eveningness Questionnaire for Children andAdolescents (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 underwenttwo non-consecutive weeks of actigraphy in one-month period to objectively assess: habitualsleep timing through the midpoint of sleep (MS); habitual sleep quality through the parameter of sleepefficiency (SE); and habitual sleep duration through the parameter of total sleep time (TST). Participantsalso 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 obtainedby students in their school leaving exams taken at the end of the school year.Results: A significant positive correlation was observed between SE and exam grades, as well as MEQCAscores and grades. Multiple regression analysis showed that only SE was significantly and positivelyrelated to the final grade.Conclusions: Examining objective and ecological measures, SE (indicator of sleep quality) had the strongesteffect on school achievement in adolescents.