Sleep problems in children with attention-deficit/hyperactivity disorder: Impact of subtype, comorbidity, and stimulant medication

Objective: To determine the relationship of sleep problems to attention-def icit/hyperactivity disorder (ADHD), diagnostic subtype, camorbid disorders, and the effects of stimulant treatment. Method: On the basis of clinical d iagnostic interviews, children aged 6 to 12 years were assigned to 4 groups : unmedicated ADHD (n = 79), medicated ADHD (n = 22), clinical comparison ( n = 35), and healthy nonclinical comparison (n = 36). These groups were com pared on 2 sleep questionnaires completed by the parents that assessed curr ent sleep problems and factors associated with sleep difficulties (i.e., sl eep routines, sleep practices, child and family sleep history). Results: Fa ctor analysis revealed 3 sleep problem categories: dyssomnias, parasomnias, and sleep-related involuntary movements. Linear regression analyses showed that (1) dyssomnias were related to confounding factors (i.e., comorbid op positional defiant disorder and stimulant medication) rather than ADHD; (2) parasomnias were similar in clinical and nonclinical children; and (3) the DSM-IV combined subtype of ADHD was associated with sleep-related involunt ary movements. However, sleep-related involuntary movements were more highl y associated with separation anxiety. Conclusions: The results suggest that the relationship between sleep problems and ADHD is complex and depends on the type of sleep problem assessed as well as confounding factors such as comorbid clinical disorders and treatment with stimulant medication.