Autistic children's sleep patterns

A study shows that autistic children sleep for shorter periods of time and wake more easily than non-autistic children.

Sleep problems are common in children with Autism. Studies have revealed that 50 to 80% of children with autism experience sleep difficulties at some time. Past research has focused on disrupted sleep patterns linked to Autism however; the quality of the evidence accumulated to date has often been compromised by small sample size, lack of agreed definitions, and poor comparability of study participants.

In this new study researchers examined longitudinal sleep patterns in children with autistic spectrum disorders (ASDs) by using long term data from the Avon Longitudinal Study of Parents and Children (ALSPAC), a cohort study of children born in Avon, England during 1991 and 1992. The study tracked the health and development of more than 14,000 children.

Parents were asked about their children's sleeping patterns when their kids were 6, 18, 30, 42, 69, 81, 115 and 140 months old, including when their children routinely went to bed and woke up on week days, and how much time they spent sleeping during the daytime.

Researchers also took into account other key information that included the results of the validated The Social Communications Disorders Check List (SCDC) a questionnaire completed by parents which measures social reciprocity and verbal/non-verbal characteristics similar to those found in Autism. The Wechsler Intelligence Scale for Children (WISC-III) was administered at age seven years. TheWISC-III considers a variety of constructs in determining the Full Scale Intelligence Quotient.

Eighty six of the children had been diagnosed with autistic spectrum disorders by the time they were 11 years old. Thirty had classic autism; 15 had atypical autism; and 23 had Asperger's syndrome.

The final analysis was based on 39 children with autistic spectrum disorders and 7043 typical children for who complete data across all time points were available.

Before the age of 30 months (2.6 yrs.) there was no major difference in sleep patterns between the two groups. However, from 30 months onwards, children with autistic spectrum disorders tended to sleep less in total, with the greatest discrepancy (43 minutes) persisting up to 140 months of age, a difference that remained significant after adjusting for sex, ethnicity, high parity and epilepsy.

The reduction in total sleep was wholly due to changes in night rather than daytimesleep duration. Night-time sleep duration was shortened by later bedtimes and earlierwaking times. Frequent waking (3 or more times a night) was also evident among the children with ASD from 30 months of age.

When it comes to disturbed sleep patterns the authors suggested that an increasing body of data suggests that production of the sleep hormone melatonin may be impaired in some children with autistic spectrum disorders.

The authors acknowledge it is unclear just what impact this shortened sleep pattern may have, however they point out that other researchers have suggested that sleep loss may have impact on neuronal development.

"If this hypothesis of cumulative sleep reduction resulting in neuronal loss is confirmed, then clinically [children with autism] might gain from even a small consistent increase in total sleep time," write the team.

In their conclusion the researchers write “Sleep duration in children with ASD is reduced from 30 months of age and persists until adolescence.”

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