Sleeping Toward Behavioral Regulation: Relations Between Sleep and Externalizing 
      Symptoms in Toddlers and Preschoolers
Objective: The aim of this study was to investigate the concurrent and longitudinal relations between sleep and externalizing symptoms among young children. Method: Sixty-four families (mostly Caucasian; 36 boys) were met twice, when children were 2 (T1) and 4 years of age (T2). At T1, children wore an actigraph monitor for a 72-hour period, and both mothers and fathers completed the Child Behavior Checklist (CBCL). At T2, both parents as well as the daycare educator filled the CBCL. Results: At T1, longer sleep duration and higher sleep efficiency was associated with fewer externalizing symptoms as assessed by mothers. Results also indicated that higher sleep efficiency at T1 was related to fewer parent-reported externalizing symptoms at T2 (while controlling for prior externalizing symptoms). Relations between sleep efficiency at T1 and externalizing symptoms as assessed by mothers at T1 and by fathers at T2 were moderated by child sex, such that links were significant among boys only. Results pertaining to educators’ reports were inconclusive. Conclusions: The current study highlights the importance of rapidly treating sleep difficulties, which are associated with persistent behavioral maladjustment, perhaps especially for boys.
Child sleep Externalizing symptoms Actigraphy Preschoolers