About a quarter of Australian school children will experience sleep problems, and most of these children will show impaired daytime functioning and poorer academic performance. Sleep disturbances are even more common in children with disorders of attention, such as autism and asperger's syndrome. The role of attention in the effect of sleep disturbance on development are not known. We will study for the first time the inter-relationship between sleep disturbance, attention and the development of cognitive abilities in typically developing primary school aged children and in children with autism and asperger's syndrome. Importantly, we will use objective measures to assess sleep disturbance, attention and cognitive abilities.