Relationship between sleep and measures of attention, executive functions, and processing speed in children with autism spectrum disorder: systematic review.

Sleep disorders represent a common comorbidity among children and adolescents with autism spectrum disorder with prevalence ranging from 50 to 80%. Poor quality sleep has negative impact on individuals' cognitive functions such as self-regulation, attention, executive functions, memory, and speed of processing. The aim of this literature review was to examine the correlation between sleep and measures of attention, executive functions, and processing speed among children with autism. This review included research articles published between 2012 and May 2022 in PubMed and Scopus databases, using the keywords "sleep" AND "attention" OR "executive functions" OR "processing speed" AND "autism" AND "children". These key-words were accompanied by synonym, close-related, or underlying terms using the Boolean connector OR. 1226 results yielded but the total number of original papers was reduced to 90 after checking for duplicate publications and title/abstract screening. 68 out of the 90 articles were excluded as irrelevant to the scope of the present study, after reading the full text. As a result, 22 studies were included in the present review, which was compiled by the PRISMA protocol. Exclusion criteria were papers published in any other language rather than English, non-research articles and studies in typically developing and/or adult population. Regarding the measurement of sleep quality, most studies used subjective measures, such as questionnaires with reports and parental observations of participants' sleep habits and behaviours. In terms of measuring the under examination cognitive functions, most studies used subjective rather than objective instruments. In the case of attention, most studies tested it as a unitary construct by using questionnaires. Contrary, regarding Executive Functions, the majority of studies examined specific aspects, such inhibition, shifting and working memory, rather than executive functions as a unitary construct. Results showed a strong correlation between sleep and measures of attention, whereas results for executive functions and processing speed are less clear. Early and accurate diagnosis of sleep disorders could prove to be crucial in the regulation of these cognitive functions in children with autism, as it implies early and targeted intervention. Conclusively, further research on sleep quality improvement interventions is needed in autism individuals.