Adults with AS display a high grade of insomnia. Sleep patterns of AS adults have similarity to those described in AS children but to date it is unclear whether insomnia in this population is due to comorbid psychiatric disorders or of the AS itself or a combination of both factors. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC270035/)

A growing body of evidence indicates that people with autism frequently experience sleep disorders and exhibit atypical sleep architecture. In order to establish whether sleep disorders truly belong to the autism spectrum disorder (ASD) phenotype, we conducted a subjective and objective study of sleep in a group of high-functioning adults with ASD but without sleep complaints, psychiatric disorders or neurological comorbidity.
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In conclusion, these findings indicate that atypicalities of sleep constitute a salient feature of the adult ASD phenotype and this should be further investigated in younger patients. Moreover, the results are consistent with an atypical organization of neural networks subserving the macro- and microstructure of sleep in ASD. (http://brain.oxfordjournals.org/content/128/5/1049.full)

Twenty-eight (0.8%) of 3700 children fulfilled the selected criteria for ASP [Autism Spectrum Problems] at both waves, and the prevalence of chronic insomnia was more than ten timeshigher 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).
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Looking at other risk factors for sleep problems in ASP children, the presence of hyperactivity symptoms as measured by the SDQ was a strong and independent risk factor for sleep problems in children with ASP. Children with ASD are at a much increased risk for having a co-morbid attention deficit hyperactivity disorder (ADHD) or ADHD symptoms (Corbett and Constantine, 2006; Goldstein and Schwebach, 2004; Rommelse et al., 2010), and our study shows that this additionally increases the risk for sleep problems. This finding is in line with previous studies on children with ASD, which have also found a relationship between sleep problems and psychopathology, including ADHD (DeVincent et al., 2007).
(http://folk.uib.no/phpbs/files/autism.pdf)