Children's objective and subjective sleep disruptions: links with afternoon cortisol levels.

OBJECTIVE: The purpose of this study was to determine possible relations between the quality and amount of children's sleep and cortisol in healthy children. DESIGN: Children's sleep was monitored with actigraphs for 7 nights. Children came to the laboratory to provide saliva samples, which were used to assess cortisol. Children reported on their sleepiness and sleep/wake problems. Sixty-four healthy children participated (M = 8.75 years; SD = .55). MAIN OUTCOME MEASURES: Self-reported sleepiness and sleep/wake problems, actigraphy-measured total sleep minutes, sleep efficiency, minutes awake after sleep onset, and sleep activity, and afternoon cortisol levels. Results: After controlling for demographic variables and child characteristics, higher levels of cortisol were related to increased subjective sleep problems and objective measures of shorter sleep duration and poorer sleep quality. CONCLUSION: These findings are of importance for understanding critical facets of children's health and well-being, and are noteworthy given the high prevalence of sleep disruptions in otherwise normally developing children in the United States.