Sleep patterns and behaviour in typically developing children and children with autism, Down syndrome, Prader-Willi syndrome and intellectual disability Sue M. Cotton a, *, Amanda L. Richdale b a Orygen Youth Health Research Centre, Centre for Youth Mental Health, University of Melbourne, Locked Bag 10, 35 Poplar Road, Parkville, Victoria 3052, Australia b Olga Tennison Autism Research Centre, School of Psychological Science, La Trobe University, Bundoora, Victoria, Australia 1. Introduction Aberrant sleep patterns commonly occur in children with an intellectual disability (ID), and include frequent daytime sleeping, daytime sleepiness, difficulties setting at bedtime, repeated nocturnal awakenings and early morning awakenings. Estimates of the prevalence of sleep difficulties in children with an ID range from 24% to 86% (Bartlett, Rooney, & Spedding, 1985; Didden, Korzillius, van Aperlo, van Overloop, & de Vries, 2002; Quine, 2001; Robinson & Richdale, 2004). Bedtime disturbances have been estimated to be as high as 50% in children with an intellectual disability (ID; Bartlett et al., 1985), with approximately 39% of the children having shortened sleep patterns (Poindexter & Bihm, 1994). A problem with many of the studies of sleep in children with an ID is the heterogeneity of participant samples. There is often a lack of consideration of the aetiology of the ID with samples often comprising children with a variety of disorders such as autism spectrum disorders, Down syndrome (DS), cerebral palsy, fragile-X syndrome, and Prader-Willi syndrome (PWS) (Bartlett et al., 1985; Clements, Wing, & Dunn, 1986; Quine, 1991). It has been postulated that the nature and extent of sleep Research in Autism Spectrum Disorders 4 (2010) 490–500 ARTICLE INFO Article history: Received 16 November 2009 Accepted 24 November 2009 Keywords: Autism spectrum disorders Down syndrome Prader-Willi syndrome Sleep Behaviour ABSTRACT Sleep problems have often been reported in children with intellectual disabilities (ID). How anomalies in 24-h sleep patterns relate to behaviour difficulties in children with different types of ID remains to be elucidated. The purpose of this study was to assess 24-h sleep and behaviour patterns in children with a variety disorders including autism (n = 34), Down syndrome (DS, n = 12), Prader-Willi syndrome (n = 12), and children with intellectual impairments due to unknown etiologies (n = 24). 33 typically developing (TD) children served as a control group. 24-h sleep and behavioural data were accumulated over a 14-day period using diary methodology. Group differences in daytime behaviour and sleep patterns were noted with children with DS being quieter, having higher levels of daytime sleepiness, and being better behaved than children with autism. Daytime napping was significantly more prevalent in children with PWS than children with autism and TD children. At bedtime children with autism were less likely to be sleepy, and were poorly behaved, which was reflected in a longer sleep latency and later time asleep. Poorer night-time sleep quality and reduced 24-h sleep time were also noted in the autism group. These findings are of clinical importance, as they indicate that different interventions may be required to treat sleep and behaviour problems in children with different developmental disabilities. ß 2009 Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: +61 3 9342 2859; fax: +61 3 9342 2941. E-mail addresses: smcotton@unimelb.edu.au (S.M. Cotton), a.richdale@latrobe.edu.au (A.L. Richdale). Contents lists available at ScienceDirect Research in Autism Spectrum Disorders Journal homepage: http://ees.elsevier.com/RASD/default.asp 1750-9467/$ – see front matter ß 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.rasd.2009.11.006