Sleep exerts a dual effect on learning: on the one hand, good sleep quality allows good daytime aptitudes leading to knowledge acquisition. On the other hand, sleep after learning is necessary for knowledge consolidation. A key role of sleep has clearly been demonstrated in memory consolidation in adults. Sleep leads to strengthen memory by promoting brain plasticity. Surprisingly, sleep influence on learning stabilization has scarcely been studied during childhood and in children affected by sleep disorders. Yet, sleep disorders concern almost 30% of children and are frequently related to a worsening in academic performances. Classical neuropsychological evaluations of these children, based on daytime learning, often fail to determine cognitive profiles explaining their academic difficulties. The investigators hypothesize that a lack of sleep-dependent consolidation could take an active part in these children's cognitive and academic difficulties. This proposal aims at characterizing interactions between sleep, learning and memory processes that have not been studied in children of elementary school age (6-12 years). The investigators will evaluate sleep-dependent memory consolidation processes in children with sleep disorders before and after treatment and healthy controls. Neuropsychological testing and academic performances will be also evaluated.. The comparison of performances obtained before and after medical treatment, will allow to understand whether normalisation of sleep quality permits the restoration of sleep-dependent memory consolidation.