and (iv) rhythmicity in neuroendocrine and neurophysiological responsiveness. On this basis, we propose a neurobiological framework to guide future study, which sees circadian effects in ADHD, along with other aspects of ADHD arousal-related deficits (e.g., cognitive energetic deficits), as being the result of dysregulated locus coeruleus function. Based on this perspective specific recommendations for future research are presented.