title: Later school start time is associated with improved sleep and daytime functioning in adolescents.
abstract: OBJECTIVE
  Chronic insufficient sleep is a growing concern among adolescents and is associated with a host of adverse health consequences. Early school start times may be an environmental contributor to this problem. The purpose of this study was to examine the impact of a delay in school start time on sleep patterns, sleepiness, mood, and health-related outcomes.
  
  
  METHODS
  Boarding students (n = 197, mean age = 15.6 yr) attending an independent high school completed the School Sleep Habits Survey before and after the school start time was experimentally delayed from 8:00 a.m. to 8:25 a.m.
  
  
  RESULTS
  The delay in school start time was associated with a significant (29 min) increase in sleep duration on school nights. The percentage of students receiving 8 or more hours of sleep on a school night increased to more than double, from 18% to 44%. Students in 9th and 10th grade and those with lower baseline sleep amounts were more likely to report improvements in sleep duration after the schedule change. Daytime sleepiness, depressed mood, and caffeine use were all significantly reduced after the delay in school start time. Sleep duration reverted to baseline levels when the original (earlier) school start time was reinstituted.
  
  
  CONCLUSIONS
  A modest (25 min) delay in school start time was associated with significant improvements in sleep duration, daytime sleepiness, mood, and caffeine use. These findings have important implications for public policy and add to research suggesting the health benefits of modifying school schedules to more closely align with adolescents' circadian rhythms and sleep needs.
authors: Departments of *Psychiatry and Human Behavior and †Pediatrics, Alpert Medical School of Brown University, Providence, RI; ‡Bradley-Hasbro Children's Research Center, Rhode Island Hospital, Providence, RI; §Division of Pulmonary and Sleep Medicine, Children's National Medical Center, Washington, DC; ‖Department of Pediatrics, School of Medicine and Health Sciences, George Washington University, Washington, DC.
authors: Julie
authors: J
authors: Boergers
authors: Christopher J
authors: CJ
authors: Gable
authors: Judith A
authors: JA
authors: Owens
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D012574:Schools / Q000458:organization & administration*; D012890:Sleep / Q000502:physiology*; D013334:Students / Q000706:statistics & numerical data*; D013997:Time Factors