title: The influence of school time on sleep patterns of children and adolescents.
abstract: This epidemiological study evaluated the impact of school time on sleep parameters of children and adolescents.
  
  
  
  This cross-sectional study involved 639 elementary and high school students (mean age 13.03 years, range 8-18, 58.5% female) from the south of Brazil. Participants answered the Morningness-Eveningness Questionnaire (MEQ), and were asked about their sleeping habits on weekdays and weekends. Sleep deficit was defined as the difference between sleep duration on weekdays and weekends.
  
  
  
  The morning-school-time students presented significantly higher age, bedtime and wake up differences, sleep deficits, and social jetlag. The sleep deficit presented by girls was greater than that observed in boys of the same age. The difference between weekday and weekend waking times was also significantly greater in girls than in boys aged 13-18 years. Sleep deficit was significantly positively correlated with age and differences in wake up times, and significantly negatively correlated with MEQ scores, social jetlag, difference between weekday and weekend bedtimes, midpoint of sleep on weekends, and midpoint of sleep on weekends corrected for sleep deficit. A step-by-step multivariate logistic regression identified social jetlag, the difference between waking times on weekdays and weekends, and the midpoint of sleep on weekends as significant predictors of sleep deficit (Adjusted R(2) = 0.95; F = 1606.87; p <0.001).
  
  
  
  The results showed that school time influences the sleep parameters. The association of school schedules and physiological factors influence the sleep/wake cycle.
authors.affiliation: Laboratório de Cronobiologia do Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil; Programa de Pós-Graduação em Ciências Médicas: Psiquiatria, UFRGS, Porto Alegre, Brazil. Electronic address: alicia.ufrgs@gmail.com.
authors.forename: Alicia
authors.initials: A
authors.lastname: Carissimi
authors.affiliation: Laboratório de Cronobiologia do Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil; Programa de Pós-Graduação em Ciências Médicas: Psiquiatria, UFRGS, Porto Alegre, Brazil.
authors.forename: Fabiane
authors.initials: F
authors.lastname: Dresch
authors.affiliation: Laboratório de Cronobiologia do Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.
authors.forename: Alessandra Castro
authors.initials: AC
authors.lastname: Martins
authors.affiliation: Laboratório de Cronobiologia do Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil; Programa de Pós-Graduação em Ciências Médicas: Psiquiatria, UFRGS, Porto Alegre, Brazil.
authors.forename: Rosa Maria
authors.initials: RM
authors.lastname: Levandovski
authors.affiliation: Department of Psychiatry and Clinical Psychobiology, School of Psychology, University of Barcelona, Spain; Institute for Brain, Cognition and Behavior (IR3C), University of Barcelona, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Adan
authors.affiliation: Department of Psychology, University of Bologna, Bologna, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Natale
authors.affiliation: Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Martoni
authors.affiliation: Laboratório de Cronobiologia do Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil; Programa de Pós-Graduação em Ciências Médicas: Psiquiatria, UFRGS, Porto Alegre, Brazil; Departamento de Psiquiatria e Medicina Legal da Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Maria Paz
authors.initials: MP
authors.lastname: Hidalgo
mesh_terms: D000293:Adolescent; D001938:Brazil; D002940:Circadian Rhythm / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006184:Habits; D006801:Humans; D008297:Male; D012574:Schools; D012737:Sex Factors; D012890:Sleep / Q000502:physiology*; D013334:Students; D011795:Surveys and Questionnaires; D013997:Time Factors
keywords: Adolescent; Child; Chronotype; Circadian rhythm; School schedules; Sleep deficit