Objective: Children with autism spectrum disorder (ASD) experience greater sleep challenges than their neurotypical peers, but sleep patterns for infants later diagnosed with ASD are unknown. This study examined differences in total sleep duration and proportion of sleep experienced at night within the first 6 months of life among infants later diagnosed with ASD, infants who demonstrated subclinical characteristics of ASD and were classified as exhibiting the broad autism phenotype (BAP), and their typically developing (TD) peers. In addition, associations between infant sleep variables and developmental outcomes at 24 months were explored.
Methods: Participants included 79 infants enrolled in a prospective, longitudinal study of the early development of ASD. Between ages 1 week and 6 months, participants completed a monthly retrospective 24-hour sleep log. At 24 months, participants received a comprehensive diagnostic evaluation, including the Autism Diagnostic Observation Schedule-2 and Mullen Scales of Early Learning and Vineland-II and were clinically characterized as ASD, BAP, or TD.
Results: When accounting for the influence of age, infants later diagnosed with ASD slept less within the 24-hour period than infants in TD or BAP groups from 0 to 6 months ( p = 0.04). Percentage of sleep experienced during nighttime hours did not significantly differ between groups from 0 to 6 months ( p = 0.25). Greater nighttime sleep percentage at 6 months predicted higher receptive language ( p < 0.001) and fine motor scores ( p < 0.0001) at 24 months. Total sleep duration at 6 months did not predict any developmental outcomes at 24 months.
Conclusion: Findings suggest that differences in sleep may occur among autistic individuals earlier in life than previously documented and have cascading effects on development.
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