Internalizing and externalizing symptoms association with insomnia, SRMDs, and parasomnias in an ADHD sample and moderating effects of parental characteristics

Objective: Sleep symptoms are highly prevalent among youth with ADHD, yet their heterogeneity and links to co-occurring emotional and behavioral symptoms remain poorly understood. This study examined, within an ADHD sample, how internalizing and externalizing symptoms were associated with sleep symptoms reflecting insomnia, sleep-related movement disorder (SRMD), and parasomnias. It also examined the moderating role of parents' emotions and strategies. Methods: Parents of a national sample of 1,086 children and adolescents (ages 5-18) with ADHD completed validated measures of sleep symptoms, internalizing/externalizing symptoms, parenting practices, and parental emotions. Sleep outcomes were analyzed using binomial generalized linear models. Additional mediation and moderation models were conducted. Results: Internalizing symptoms were the strongest predictor of all sleep outcomes, whereas externalizing symptoms showed more selective associations, emerging mainly for SRMD and parasomnia symptoms. Mediation analyses were consistent with an indirect association of externalizing symptoms with insomnia through internalizing symptoms, whereas for SRMD and parasomnia symptoms both indirect and residual direct associations were observed. Parenting effects were selective: positive parenting attenuated the association between externalizing and SRMD symptoms, whereas negative parenting strengthened the association between internalizing and SRMD symptoms. Positive parental emotion attenuated the association between externalizing and parasomnia symptoms but strengthened the association between internalizing and parasomnia symptoms. Conclusion: These results are encouraging in suggesting a transdiagnostic approach aimed to better understanding the mechanisms underlying their relationship and to pave the way for the development of more refined and novel therapeutic approaches.