title: Morningness-eveningness correlates with sleep time, quality, and hygiene in secondary school students: a multilevel analysis.
abstract: At the onset of puberty, students shift their sleep to later hours, but school starts early. It is suggested that evening orientation and early school start times do not go well together. Therefore, the aim of this study was to investigate sleep problems in adolescence, and it was expected that the adolescents' eveningness orientation is associated with many sleep-related problems. Students of secondary education (n = 3201; mean = 13.8 ± 1.8 years) filled out a self-report questionnaire containing measures of morningness-eveningness, sleep time (midpoint of sleep, social "jetlag"), sleep length (on schooldays and on weekends), sleep quality, and sleep hygiene as well as questions on electronic screen media use. The impact of circadian preference on sleep time (midpoint of sleep and social jetlag), sleep length (on schooldays and on weekends), sleep quality, and sleep hygiene of adolescents was tested via multilevel analyses while controlling for covariates on the student level (age, sex, screen media use, and time leaving home) and on the class level (school type, grade level, and school start time). Morningness-eveningness was a significant predictor of all dependent variables and associations were highest (β > 0.40) for midpoint of sleep, social jetlag, problems with going to bed, problems with falling asleep, and problems with returning to wakefulness. Providing guidance for parents on sleep hygiene behavior routines for their child, an educational program in sleep hygiene, and later school start times could help to synchronize adolescents' circadian rhythms to daily educational and social demands.
authors.affiliation: Institute of Psychology, University of Education Heidelberg, Heidelberg, Germany. Electronic address: vollmer@ph-heidelberg.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Vollmer
authors.affiliation: Faculty of Psychology, University of Warsaw, Warsaw, Poland.
authors.forename: Konrad S
authors.initials: KS
authors.lastname: Jankowski
authors.affiliation: Faculty of Psychology, Complutense University of Madrid, Madrid, Spain.
authors.forename: Juan F
authors.initials: JF
authors.lastname: Díaz-Morales
authors.affiliation: Department of Biology, University of Tuebingen, Tuebingen, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Itzek-Greulich
authors.affiliation: Institute of Science, Technology & Geography, University of Education Heidelberg, Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Wüst-Ackermann
authors.affiliation: Institute of Science, Technology & Geography, University of Education Heidelberg, Heidelberg, Germany; Department of Biology, University of Tuebingen, Tuebingen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Randler
mesh_terms: D000293:Adolescent; D002940:Circadian Rhythm; D005260:Female; D005858:Germany; D006801:Humans; D006920:Hygiene; D008297:Male; D055361:Multilevel Analysis; D012890:Sleep; D013334:Students; D011795:Surveys and Questionnaires; D013997:Time Factors
keywords: Adolescents; Circadian rhythm; School start time; School type; Sleep hygiene; Sleep quality