An estimated 25-50% of children and adolescents with attention-deficit hyperactivity disorder (ADHD) experience problems with sleep. The most common sleep problems reported in children with ADHD include delayed sleep onset, sleep or bedtime resistance, prolonged tiredness upon waking and daytime sleepiness. Higher incidences of sleep disorders such as restless legs syndrome, periodic limb movement disorder and sleep-disordered breathing have been reported in paediatric ADHD populations compared with control populations. In some cases, medications for ADHD and/or co-morbid disorders may also contribute to sleep disturbances. Assessment tools, such as parent-child questionnaires and sleep diaries, can help clinicians evaluate sleep disturbances. Sleep problems may potentially exacerbate ADHD symptoms, and interventions targeted at ensuring adequate sleep (including behavioural, dietary, specific pharmacological agents for treatment-induced insomnia, and melatonin) could in turn potentially attenuate symptoms associated with ADHD, such as irritability. Whether metabolic or neurological pathways common to both sleep and ADHD may be disrupted, and whether targeting treatments to these pathways may simultaneously improve both ADHD and sleep symptoms, needs further elucidation.