Sleep disturbances are common and consequential in children with attention deficit hyperactivity disorder (ADHD). Diet also influences ADHD symptoms. Interrelationships between diet, sleep and behaviour in children diagnosed with ADHD are little studied. We investigated, via parental report, the relationships between sleep and diet in 88 Australian children aged 6-13 years old (M = 8.94, SD = 1.78). This pilot data shows that 30 per cent of the children had sleep disturbance (≥ 2 standard deviations above the mean) with significant relationships between ADHD symptoms, sleep disturbance and diet. Parents who reported more sleep disturbance also reported a higher intake of carbohydrate, fats, and, most particularly, sugar which was also a significant predictor of night time sweating. These findings suggest an interrelationship between diet and sleep in children with ADHD. Given that both sleep and dietary intake are potentially modifiable behaviours within treatment regimes of children with ADHD, further investigation is needed.