Sleep Related Behavioural and Cognitive Functioning
Several factors have been outlined as having a negative impact on cognitive and behavioral functioning of individuals with Autism Spectrum Disorders (ASD). Sleep is the main focus of the current study since a number of studies reported that children with ASD experience severe sleep problems. Since sleep has been found to play an active role in children’s memory consolidation, it is vital to assess the impract of sleep on children's functioning.
The study had two chief aims: primarily to examine sleep-dependent memory consolidation on children with ASD, and furthermore to provide insights on children’s nocturnal sleep habits in relation to their cognitive abilities. Additionally, as Greece is a country in which napping is a common practice, diurnal sleep habits of children were assessed. Participants included, 12 typically developing (TD)and 12 children with ASD (5-16 years of age).
Methods: Sleep dependent memory consolidation was assessed using Animal Names task, a recently developed child-friendly and engaging declarative memory task. Sleep was further assessed using Childhood Sleep Habits Questionnaire, a napping questionnaire and actigraphy.
Results: Repeated measures ANOVAs were conducted to assess performance between the Animal Names task sessions (Test 1, 2, 3) across each group (TD, ASD) and sleep and wake condition. TD children had higher scores than the ASD children on all tests.
TD children had higher scores on the Animal Names task following intervals of sleep, rather than wake, indicating that during periods of active sleep children’s memory traces of the animal’s names were strengthened. The new memories the children had made of the non-words improved following periods of sleep irrespective of whether the training had happened in the morning or in the evening. Contrary to expectations, despite the challenges that children with ASD experience during sleep, the positive effects of sleep remained. New memories were not merely protected and strengthened, but were also maintained after a period of 24 hours. Sleep-dependent memory consolidation was possible for children with ASD, regardless of whether the training had occurred in the morning or evening. Significant differences in Sleep Duration, Night Wakings were found between the groups. Moreover, ASD children had higher CSHQ total scores than TD children. Children with ASD had significantly higher sleep onset delay and decreased sleep.
Conclusions: The findings suggest that sleep, does in fact play an active role in children with ASD, despite the reported sleep problems which are suggested to characterize them. Due to the scarcity of previous research on the area, the findings of the study emphasize the importance of sleep in children with ASD and stress its role in the process of learning. It is concluded, that sleep had a strengthening and stabilizing effect on the memories of both TD and children with ASD.
Gaining better understanding of the influence of sleep on children with ASD is important for the creation of teaching interventions. Such understandings will aid children’s learning and development. It is therefore essential that teachers, educators and researchers focus on transmitting to parents and children the prominent role of sleep.