The major recent advance in our understanding of paediatric sleep is the publication of reference values for sleep in children aged 3.2-8.6 years. These data show developmental changes reflecting a subtle process of the maturation of the central nervous system with regard to sleep in childhood. In infants, a significant negative correlation has been observed between a snore-associated arousal index and an infant development scale, underlining that snoring is less innocent than has been suggested. A link between obstructive sleep apnoea (OSA) and airway inflammation has been demonstrated, with children with OSA having significantly higher expression of the leukotriene (LT) 1 and 2 receptors and higher concentrations of LT C4/D4/E4 and LT B4 in adenotonsillar tissues than children with recurrent rhinitis who have no OSA. This explains the efficacy of treatment for OSA with montelukast, a LT receptor antagonist, alone or in combination with corticosteroids. By using peripheral arterial tonometry, a noninvasive technique that allows the moment-to-moment measurement of sympathetic tone, persistent waking-associated autonomic nervous system dysfunction has been demonstrated in young children with sleep-disordered breathing (SDB). As such, SDB in childhood may represent a cardiovascular risk factor in adulthood.