Study objective: To review evidence on sleep and alertness in children with attention-deficit/hyperactivity disorder (ADHD) controlling for potential confounding factors.
Methods: A PubMed search. Studies using ADHD diagnostic criteria other than DSM-III-R or IV and studies not excluding or controlling for psychiatric comorbidity or medication status were not included in the review. Results from objective studies were combined using meta-analysis.
Results: From the 46 studies located, 13 were retained. With regard to objective studies, the proportion of subjects who fell asleep during the Multiple Sleep Latency Test, the number of movements in sleep, and the apnea-hypopnea index were significantly higher in children with ADHD than in controls. We found no significant differences in other objective parameters (sleep-onset latency; number of stage changes; percentages of stage 1 sleep, stage 2 sleep, slow-wave sleep, or rapid eye movement sleep; rapid eye movement sleep latency; and sleep efficiency). Limited evidence from subjective studies suggests no significant differences in sleep-onset difficulties and bedtime resistance between children with ADHD and controls, after controlling for comorbidity and medication status. Data on sleep duration, night and morning awakenings, and parasomnias are still very limited.
Conclusion: Results from our systematic review suggest that children with ADHD have higher daytime sleepiness, more movements in sleep, and higher apnea-hypopnea indexes compared with controls. Given the limited number of studies controlling for confounding factors, further subjective and objective studies are needed to better understand alterations in sleep and alertness in children with ADHD.