title: Academic performance in adolescents with delayed sleep phase.
abstract: BACKGROUND
  Delayed sleep phase (DSP) in adolescence has been linked to reduced academic performance, but there are few population-based studies examining this association using validated sleep measures and objective outcomes.
  
  
  METHODS
  The youth@hordaland-survey, a large population-based study from Norway conducted in 2012, surveyed 8347 high-school students aged 16-19 years (54% girls). DSP was assessed by self-report sleep measures, and it was operationalized according to the International Classification of Sleep Disorders - Second Edition. School performance (grade point average, GPA) was obtained from official administrative registries, and it was linked individually to health data.
  
  
  RESULTS
  DSP was associated with increased odds for poor school performance. After adjusting for age and gender, DSP was associated with a threefold increased odds of poor GPA (lowest quartile) [odds ratio (OR) = 2.95; 95% confidence interval (CI): 2.03-4.30], and adjustment for sociodemographics and lifestyle factors did not, or only slightly, attenuate this association. Adjustment for nonattendance at school reduced the association substantially, and in the fully adjusted model, the effect of DSP on poor academic performance was reduced to a non-significant level. Mediation analyses confirmed both direct and significant indirect effects of DSP on school performance based on school absence, daytime sleepiness, and sleep duration.
  
  
  CONCLUSIONS
  Poor academic performance may reflect an independent effect of underlying circadian disruption, which in part could be mediated by school attendance, as well as daytime sleepiness and short sleep duration. This suggests that careful assessment of sleep is warranted in addressing educational difficulties.
authors: Division of Mental Health, Norwegian Institute of Public Health, Kalfarveien 31, N-5018 Bergen, Norway; The Regional Centre for Child and Youth Mental Health and Child Welfare, Uni Research Health, P.O. Box 7810, N-5020 Bergen, Norway; Department of Psychiatry, Helse Fonna HF, P.O. Box 2170, N-5504 Haugesund, Norway. Electronic address: borge.sivertsen@fhi.no.
authors: Børge
authors: B
authors: Sivertsen
authors: Brain and Mind Research Institute, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, NSW 2050, Australia.
authors: Nick
authors: N
authors: Glozier
authors: Department of Psychology, University of California, 2205 Tolman Hall #1650, Berkeley, CA 94720-1650, USA.
authors: Allison G
authors: AG
authors: Harvey
authors: The Regional Centre for Child and Youth Mental Health and Child Welfare, Uni Research Health, P.O. Box 7810, N-5020 Bergen, Norway.
authors: Mari
authors: M
authors: Hysing
mesh_terms: D000041:Absenteeism; D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology*; D004521:Educational Measurement; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D009664:Norway; D057566:Self Report; D012893:Sleep Wake Disorders / Q000523:psychology*; D012959:Socioeconomic Factors; D055815:Young Adult
keywords: Academic performance; Adolescence; Delayed sleep phase; Epidemiology