Behavioral sleep problems and internalizing and externalizing comorbidities in children with attention-deficit/hyperactivity disorder

Behavioral sleep problems are common in children with attention-deficit/hyperactivity disorder (ADHD), as are internalizing and externalizing comorbidities. The prevalence of these difficulties and the extent to which they co-exist in children with ADHD could inform clinical practice, but remains unclear. Therefore, we examined the association between sleep problems and internalizing and externalizing comorbidities in children with ADHD. Children aged 5-13 years were recruited from 21 pediatric practices across Victoria, Australia (N = 392). Internalizing and externalizing comorbidities (none, internalizing, externalizing, co-occurring) were assessed by the telephone-administered Anxiety Disorders Interview Schedule for Children IV/Parent version. Sleep problem severity was assessed by primary caregiver report (no, mild, moderate or severe problem). Moderate/severe sleep problems were confirmed using International Classification of Sleep Disorders. Seven specific sleep problem domains (bedtime resistance, sleep anxiety, sleep onset delay, sleep duration, night waking, parasomnias and daytime sleepiness) were assessed using the Children's Sleep Habits Questionnaire. Data were analyzed using adjusted logistic and linear regression models. Compared to children without comorbidities, children with co-occurring internalizing and externalizing comorbidities were more likely to have moderate/severe sleep problems (adjusted OR 2.4, 95 % CI 1.2; 4.5, p = 0.009) and problematic sleep across six of seven sleep domains. Children with either comorbidity alone were not at risk of moderate/severe sleep problems, but at the sleep domain level, children with internalizing alone had more sleep anxiety, and those with externalizing alone had less night waking. In conclusion, children with ADHD experiencing co-occurring internalizing and externalizing comorbidities are at an increased risk of sleep problems.