Executive Dysfunction in Children with ADHD and Sleep Problems: Does Physical Activity Matter?

BACKGROUND: Children with attention deficit hyperactivity disorder (ADHD) experience high rates of sleep problems and have an increased risk of executive dysfunctions and physical inactivity. Physical activity (PA) may be protective; however, few studies have objectively measured PA, sleep parameters and executive functions (EFs) in ADHD populations. This study aimed to assess PA and sleep using wearable motion sensors and to examine the relationships with EFs in children with ADHD. METHODS: The ActiGraph GT9X Link accelerometer was used to measure PA and sleep parameters in 282 children with ADHD (age range: 6-12 years; mean age = 8.59 ± 1.35 years; 78.4% boys) over seven consecutive days. Sleep status was assessed using the Pittsburgh Sleep Quality Index (PSQI), with scores ≥5 indicating poor sleep quality. Core EFs (i.e., inhibitory control, working memory, and cognitive flexibility) were assessed using Inquisit Lab™ 5. RESULTS: Within this large, well-characterized ADHD cohort, approximately 60% of children exhibited sleep problems. Compared with children with ADHD without sleep problems, those with sleep problems demonstrated longer actigraphy-derived sleep latency, poorer performance on cognitive flexibility tasks, spent less time per day in moderate-to-vigorous physical activity (MVPA), and were less likely to meet the World Health Organization-recommended 60 minutes of MVPA. Self-reported sleep quality, sleep efficiency, daytime dysfunction, and MVPA guideline attainment were significantly associated with EFs in children with ADHD. The relationships between daytime dysfunction and cognitive flexibility were moderated by MVPA guideline attainment. CONCLUSIONS: Daytime dysfunction predicts poorer cognitive flexibility only in children with ADHD who engage in low PA levels. Further investigation is warranted to determine whether adherence to MVPA guidelines can mitigate sleep problems and executive dysfunction.