Sleep habits and sleep problems among children born extremely preterm: A Norwegian population-based cohort study

Objective: The objective of this thesis was to investigate the prevalence of general and specified sleep problems during childhood and the sleep habits of children aged 11 years who had been born extremely preterm (EPT). Furthermore, the study aimed to explore possible associations between sleep characteristics and neurodevelopmental disabilities (NDD), prenatal and neonatal factors, behaviour and respiratory health. Methods: A national cohort of all EPT children (gestational age [GA] < 28 weeks or birth weight< 1,000 g) born in Norway in 1999–2000 was investigated. In Paper 1, parental questionnaires mapped the children’s current sleep habits at 11 years of age and the prevalence of general and specified sleep problems throughout childhood up to this age. The prevalence of sleep problems throughout childhood and sleep habits at 11 years of age were compared with those of a control group. The EPT children were clinically assessed and given an NDD score at five years of age. In Papers 2 and 3, four current specified sleep problems, namely, difficulty falling asleep or frequent awakenings, snoring, daytime sleepiness and non-recommended sleep duration (