title: Do later wake times and increased sleep duration of 12th graders result in more studying, higher grades, and improved SAT/ACT test scores?
abstract: BACKGROUND
  The aim of this study was to investigate the relationship between sleep duration, wake time, and hours studying on high school grades and performance on the Scholastic Aptitude Test (SAT)/ American College Testing (ACT) college entrance exams.
  
  
  METHODS
  Data were collected from 13,071 recently graduated high school seniors who were entering college in the fall of 2014. A column proportions z test with a Bonferroni adjustment was used to analyze proportional differences. Analysis of covariance (ANCOVA) was used to examine mean group differences.
  
  
  RESULTS
  Students who woke up prior to 6 a.m. and got less than 8 h of sleep (27 %) were significantly more likely to report studying 11 or more hours per week (30 %), almost double the rate compared to students who got more than 8 h of sleep and woke up the latest (16 %). Post hoc results revealed students who woke up at 7 a.m. or later reported significantly higher high school grades than all other groups (p < 0.001), with the exception of those students who woke up between 6:01 a.m. and 7:00 a.m. and got eight or more hours of sleep. The highest reported SAT/ACT scores were from the group that woke up after 7 a.m. but got less than 8 h sleep (M = 1099.5). Their scores were significantly higher than all other groups.
  
  
  CONCLUSIONS
  This study provides additional evidence that increased sleep and later wake time are associated with increased high school grades. However, this study also found that students who sleep the longest also reported less studying and lower SAT/ACT scores.
authors.affiliation: Center for Postsecondary Research, Indiana University, 1900 East 10th St, Suite 419, Bloomington, IN, 47406, USA. colejs@indiana.edu.
authors.forename: James S
authors.initials: JS
authors.lastname: Cole
mesh_terms: D000293:Adolescent; D001077:Aptitude Tests / Q000706:statistics & numerical data*; D002940:Circadian Rhythm; D003099:College Admission Test / Q000706:statistics & numerical data*; D004522:Educational Status; D005260:Female; D006801:Humans; D008297:Male; D009042:Motivation; D000070263:Sleep Hygiene; D013223:Statistics as Topic; D013334:Students / Q000523:psychology*; D014851:Wakefulness
keywords: Academic performance; Sleep duration; Studying; Wake time