“…Based on our hypothesis of disrupted arousal-related circadian rhythm in ADHD (i.e., hypo-and hyperarousal at different times of day), we expected (i) a significant difference in cortisol increase after awakening among the three groups (ADHD+ODD, ADHD, and controls), and (ii) a significant interaction of group x time, reflecting that group differences in cortisol level depend on the time of day when samples were collected for these measurements. The influence of other factors that may modulate levels of arousal such as age, sex, pubertal stage, body mass index (BMI) (Adam, 2006;Oskis, et al, 2009), and internalizing problems (such as depressive and anxiety symptoms) (Van den Bergh, Van Calster, Pinna Puissant, & Van Huffel, 2008) was evaluated, also.…”