Attention‐Deficit/Hyperactivity Disorder Through a Circadian Lens: When the Brain's Clock Disrupts Attention Regulation

ABSTRACT Attention‐deficit/hyperactivity disorder (ADHD) is increasingly linked to disturbances in circadian regulation, yet this temporal dimension remains insufficiently integrated into research and clinical practice. This perspective synthesises current evidence on circadian misalignment in ADHD, reframing commonly reported sleep disturbances and diurnal symptom variability within a chronobiological context. Drawing on the two‐process model of sleep regulation, we distinguish sleep insufficiency from delayed circadian phase and highlight how misalignment between endogenous timing and externally imposed schedules may exacerbate attentional and executive dysfunction. Convergent findings from behavioral phenotyping, dim light melatonin onset (DLMO) and cortisol dynamics indicate systematic alterations across development. We further review emerging chronotherapeutic strategies, including melatonin and light‐based interventions and discuss their methodological and translational limitations. Greater integration of objective circadian markers into assessment and intervention may enhance precision and inform future mechanistic and clinical research in ADHD.