Sleep disturbance and cognitive functioning in children with attention-deficit/hyperactivity disorder

Abstract

Children with attention-deficit/ hyperactivity disorder (ADHD) were found to experience greater sleep disturbance than healthy developing children. Sleep disturbance is related to poorer neurocognitive functioning, yet the contribution of sleep disturbance on the neurocognitive impairments in children with ADHD remains unclear at this stage. This thesis consisted of two studies that aimed at investigating the association between parent reported sleep disturbance (Child Sleep Habits Questionnaire) and objectively measured cognitive functioning in children with ADHD (aged 6-12 years). Study 1 was a case control study comparing the cognitive functioning between ADHD children with no or mild sleep problem (n = 31) and those with moderate or severe sleep problem (n = 31). Study 2 was a pilot study evaluating the effects of behavioural sleep intervention for ADHD children with moderate or severe sleep problem (n = 16) on cognitive functioning. Results from study 1 found that the severity of parent reported sleep problem was significantly associated with the reaction time on the continuous performance task and the number of perseverative response on the card sorting task. Results from study 2 found sleep-focused intervention led to a significant improvement in response latency on the letter-digit substitution task in children with ADHD. Parent-reported behavioural sleep problems, particularly insomnia symptoms, were associated with impaired attention and executive functioning in children with ADHD. Furthermore, preliminary evidence suggested that parent-based behavioural sleep intervention could potentially improve cognitive performance (enhancement in processing speed) in children with both ADHD and sleep problem.