The links between attention-deficit hyperactivity disorder (ADHD) and sleep disorders remain unclear. Specific sleep disorders are a frequent comorbid condition associated with ADHD according to a categorical approach. However, sleep disorders can also induce ADHD-like symptoms according to a dimensional approach and are thought to be the consequence of excessive daytime sleepiness. It may thus be difficult for clinicians to differentiate the diagnosis of ADHD comorbid with a sleep disorder from sleep disorders with ADHD-like symptoms. This distinction could be important for the appropriate management of patients with dual complaints of trouble maintaining attention and daytime sleepiness. This paper summarizes the main sleep disorders associated with ADHD: sleep-related breathing disorders, sleep-related movement disorders, circadian rhythm sleep-wake disorders, and central disorders of hypersomnolence (aka hypersomnias). The history of presenting symptoms should be taken into account since ADHD is a neurodevelopmental disorder whereas ADHD symptoms comorbid with sleep disorder are not. Finally, we propose a model to clarify the links between ADHD, ADHD symptoms, and excessive daytime sleepiness induced by sleep disorders. Clinicians should therefore routinely assess, monitor, and manage the sleep problems of patients with ADHD who have both comorbidities and should search for the presence of ADHD symptoms in subjects with sleep disorders.