Attention deficit hyperactivity disorder (ADHD) is the most common problem presented to child and adolescent mental health services (CAMHS) and occurs in 4–6% of schoolage children. The core symptoms of ADHD – inattention, hyperactivity and impulsiveness – are often associated with difficulties in regulating behaviour; these are strikingly similar to the difficulties caused by disrupted sleep and sleep deprivation. Sleep problems in children have, therefore, often been associated with ADHD. Sleep–wake disorders have even been included in the diagnostic criteria for ADHD in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) and are often included in ADHD rating scales; for example, Conners’ Rating Scale for parents. It has been theorised that sleep deprivation in children with ADHD could be the result of a primary sleep disorder, or that it could be related to dysregulation of arousal mechanisms, as implicated in the aetiology of ADHD.