Sleep Architecture and Phenotype In Children with Autism

Background:  Disrupted sleep in children is associated to behavioral problems during daytime. Children with autism present with high prevalence of sleep disorders as reported by parents, including long sleep latency and nocturnal awakenings. Laboratory polysomnographic recordings support these observations. Poor sleep in children with autism may thus be associated with disturbances in daytime functioning and modulate core symptoms of autism.

Objectives: 1- To compare sleep characteristics of children with autism, as measured with questionnaires filled by parents and laboratory polysomnography; 2- To evaluate the relationship between sleep characteristics in children with autism and core symptoms of autism.

Methods: Thirteen boys diagnosed with autism according to DSM-IV criteria (ASD: 10.7 ± 1.9 years) and 21 typically-developing boys (10.7 ±1.7) spent 2 consecutive nights in a sleep laboratory. All had a normal IQ and were free of psychiatric or neurologic conditions. None reported difficulties with sleep. Sleep was evaluated in two ways: 1) The Children’s Sleep Habits Questionnaire (CSHQ), filled by parents; 2) Polysomnographic recordings. The ADI-R (current scores) measured daytime functioning. Groups were compared using t-tests for independent samples. Pearson’s correlation coefficients evaluated the association between sleep and daytime functioning.

Results: The CSHQ showed that ASD children have more problems than TD children with sleep onset delay and sleep duration. Compared to the TD group, polysomnographic recordings of ASD children showed a longer sleep latency (30.4 ± 7.2 min, vs. 13.5 ± 4.6; p=0,006), more awakenings (15.54 ± 2.47 min, vs. 13.97 ± 2.31; p=0.055 ), less slow-wave sleep (18.4 ± 0.8 %, vs. 24.0 ± 1.3 %; p=0.002), but the same amount of REM sleep (18,9 ± 0,9 %, vs. 17,0 ± 1,0; p=0,186). The density of EEG sleep spindles per hour of stage 2 was the same over the central electrodes (294.4 ± 32.0, vs. 288.4 ± 26.7; p= p=0.70) but inferior over the frontal electrodes (147.1 ± 19.6 vs. 213.0 ± 26.9; p= p=0.08). In the ASD group, CSHQ sleep latency showed a positive correlation with ADI-R on the communication (r=0.72; p=0.008) and the repetitive behavior scale (r=0.665; p= 0.018) sum scores; CSHQ daytime sleepiness showed a positive correlation with the ADI-R socialization sum score (r= 0.590; p=0.043); PSG sleep efficiency showed a negative correlation with the ADI-R on the communication sum score (r= -0.742, p=0.006).

Conclusions: Objective and subjective measures show signs and symptoms of alterated sleep in children with autism. Sleep atypicalities in children with autism is associated with prototypicality of the autism phenotype: the more the sleep is modified in comparison to typical individuals, the higher are the scores indexing the atypicality of the autism phenotype.