Insomnia symptoms, objective sleep duration and hypothalamic-pituitary-adrenal activity in children

Background Insomnia symptoms are the most common parent-reported sleep complaints in children; however, little is known about the pathophysiology of childhood insomnia symptoms, including their association with hypothalamic-pituitary-adrenal (HPA) axis activation. The objective of this study is to examine the association between parent-reported insomnia symptoms, objective short sleep duration and cortisol levels in a population-based sample of school-aged children. Design A sample of 327 children from the Penn State Child Cohort (5-12years old) underwent 9-h overnight polysomnography and provided evening and morning saliva samples to assay for cortisol. Objective short sleep duration was defined based on the median total sleep time (i.e., <77h). Parent-reported insomnia symptoms of difficulty initiating and/or maintaining sleep were ascertained with the Pediatric Behavior Scale. Results Children with parent-reported insomnia symptoms and objective short sleep duration showed significantly increased evening (0.33 +/- 0.03g/dL) and morning (1.38 +/- 0.08 mu g/dL) cortisol levels. In contrast, children with parent-reported insomnia symptoms and normal' sleep duration showed similar evening and morning cortisol levels (023 +/- 003g/dL and 113 +/- 008g/dL) compared with controls with normal' (028 +/- 002g/dL and 110 +/- 004g/dL) or short (028 +/- 002g/dL and 113 +/- 004g/dL) sleep duration. Conclusions Our findings suggest that insomnia symptoms with short sleep duration in children may be related to 24-h basal or responsive physiological hyperarousal. Future studies should explore the association of insomnia symptoms with short sleep duration with physical and mental health morbidity.