Relations between daytime pre-ejection period reactivity and sleep in late childhood.

The sympathetic nervous system and children's sleep serve critical arousal regulation functions. Shortened pre-ejection period, a reliable indirect index of greater sympathetic nervous system activity, has been associated with reduced sleep duration and quality in adults, but limited evidence exists in children regarding associations between pre-ejection period and sleep. We examined relations between pre-ejection period reactivity in response to a laboratory-based stressor and multiple parameters of actigraphy-based sleep duration and quality in children. The sample included 123 boys and 112 girls [mean age = 11.31 years, standard deviation (SD) = 0.63 years]. Controlling for body mass index, sex and pre-ejection period baseline, increased sympathetic nervous system reactivity, indexed by a lower level of pre-ejection period during the challenge than the baseline, was associated with worse sleep quality indicated by lower sleep efficiency, greater sleep activity and greater long wake episodes. The findings add to a small literature on relations between sympathetic nervous system functioning and children's sleep, suggesting that poor sleep quality is related to dysregulation of this stress response system.