The Joint contribution of sleep, intelligence and motivation to school performance

In this study.. a structural equation model was used to examine the contribution of sleep duration and sleep quality on school performance in the last two grades of elementary school. Intelligence, achievement motivation, and test anxiety were used as control variables. Mean age of the 153 children was I I years and seven months. The relationship with school performance has been modelled more explicitly by two latent variables 'chronic sleep reduction' and 'eagerness'. 'Chronic sleep reduction' is indicated by three variables: usual time in bed during school days, bedtime at the weekend, and allowance to children to set their own bedtime. The latent variable 'eagerness' is related to debilitatory and facilitatory test anxiety and it is influenced by the observed variable 'sleep quality'. The relationship of chronic sleep reduction, eagerness, achievement motivation, and intelligence with school performance (as shown in the model) demonstrates that less chronic sleep reduction, greater eagerness, higher achievement motivation and intelligence give rise to a better school performance. The average contribution of each of these variables is 10%. Together, these variables explain 43% of the variance in school performance. (C) 2003 Elsevier Ltd. All rights reserved.