Study objective: To determine the effects of experimental restriction of sleep opportunity on teacher ratings of academic performance and behavior in healthy normal children.
Design: Home-based, within-subjects design in which participants followed 3 week-long sleep schedules-Baseline (self-selected), Optimized, and Restricted-while attending school, with order of conditions counter-balanced (Optimized and Restricted).
Participants: Seventy-four children (39 boys; aged 6 to 12 years, mean = 10) screened for medical and psychological health.
Measurements and results: Teachers masked to assigned hours of sleep completed paper-and-pencil questionnaires at the end of each study condition. Questionnaire items were selected from several published measures. Summary scores included Academic Problems, Hyperactive-Impulsive Behaviors, Internalizing, Oppositional-Aggressive, Sleepiness, Total Attention Problems, and Mean Severity of Attention Problems. Main effects of sleep condition were found forAcademic Problems, Sleepiness, Total Attention Problems, and Mean Severity of Attention Problems. Restricting sleep increased ratings of Academic Problems (medium effect) relative to both Baseline (P < .01, eta(p)2 = .11) and Optimized (P < .05, eta(p)2 = .10) conditions and increased the Mean Severity of Attention Problems (medium effect) relative to Baseline (P < .01, eta(p)2 = .12).
Conclusions: These findings provide experimental support for widely held beliefs about the importance of sufficient time-in-bed for academic functioning in children. Reducing sleep opportunity had a direct effect on academic performance, as rated by teachers, even among healthy students with no history of behavioral problems or academic difficulty. Findings also support insufficient sleep as a direct source of variability in the manifestation of attention problems but not hyperactivity.