Nonsignificance of sleep relative to IQ and neuropsychological scores in predicting academic achievement.

OBJECTIVE: The goal of the study was to determine the relative importance of sleep, IQ, neuropsychological, and attention-deficit/hyperactivity disorder (ADHD) scores in predicting academic achievement.
METHOD: Objective overnight polysomnograph sleep scores, parent ratings of sleep problems, IQ, neuropsychological test scores, and parent ratings of ADHD were used to predict academic achievement in a general population sample of 412 elementary schoolchildren, 6 to 12 years of age with IQs of 71 to 147.
RESULTS: Using stepwise linear regression analysis, IQ was the best single predictor of reading and math achievement test scores. The most powerful combined predictors of achievement were IQ and some of the neuropsychological test scores. Subjective parent-reported sleep problems and objective polysomnograph scores (apnea-hypopnea index, mean oxygen saturation and lowest saturation percentage during sleep, snoring frequency and severity, sleep latency, minutes to rapid eye movement (REM) sleep, arousal index, number of awakenings, sleep efficiency, and percentage of stage 1, 2, 3, 4, and REM sleep) did not contribute significantly more to the prediction of achievement. Children with and without sleep problems did not differ from each other in achievement. IQ, neuropsychological test scores, and ADHD ratings were all significantly related to achievement, but correlations between achievement and objective and subjective sleep scores were all nonsignificant.
CONCLUSIONS: There may be individual children for whom sleep problems affect achievement, but for a large group of community children, sleep was not significantly related to academic functioning. In contrast, IQ and neuropsychological test scores were powerful predictors of achievement.