This study examined the prevalence and chronicity of sleep problems in children who manifest problems believed to be typical of Autism Spectrum Disorders (ASD). Using data from a longitudinal total population study, symptoms of ASD, insomnia and potential explanatory factors were assessed at ages 7-9 and 11-13. Children were included in a group defined as having Autism Spectrum Problems (ASP) if they scored above a strict threshold on the Autism Spectrum Screening Questionnaire (ASSQ). Twenty-eight (0.8%) of 3700 children fulfilled the selected criteria for ASP at both waves, and the prevalence of chronic insomnia was more than ten times higher in these children compared to the controls. Children with ASP developed more sleep problems over time, with an incidence rate at wave 2 of 37.5% compared to 8.6% in the controls. The sleep problems were more persistent over time, with a remission rate of 8.3% compared to 52.4% in the controls. ASP was a strong predictor of sleep problems at wave 2 (OR = 12.44), and while emotional and behavioural problems explained a large proportion of this association, the effect of ASP on insomnia remained significant in the fully adjusted model (OR = 3.25). These findings call for increased awareness of sleep problems in children with ASP. (Contains 3 tables and 1 figure.)