Association of accelerometry-derived social jetlag and sleep with temperament in children less than 6 years of age.

STUDY OBJECTIVES: Social jetlag (SJL) measures the discrepancy between circadian and social clocks. Using accelerometry-derived data, our objective was to assess the prevalence of SJL in young healthy children and determine the association of SJL and sleep with temperament. METHODS: Of 117 children participating in TARGet Kids!, a Canadian cohort of healthy preschool-aged children, 78 children (39 girls; 50%; mean age [SD]: 35.1 [20.5] months) were included. Sleep was measured objectively using accelerometry. Temperament dimensions (surgency, negative affectivity, and effortful control) were assessed with the very short forms of Rothbart's child and infant behavior questionnaires. We examined associations of SJL and sleep with temperament using multivariable linear regression models adjusted for sex, age, ethnicity, and preschool/daycare attendance. RESULTS: 20 out of 78 (25.6%) experienced SJL of greater than 30 minutes. SJL was greater in children who attended preschool/daycare compared with children who did not (26.3[18.8] minutes vs 17.6 [14.8] minutes; P < .05). There was no evidence of an association between SJL and any temperament dimension. We found evidence of an association between increased sleep duration and increased negative affectivity scores (longer 24-hour sleep; ß: 0.347; 95% confidence interval: 0.182, 0.512; P < .0001; and longer nighttime sleep duration: ß: 0.413; 95% confidence interval: 0.163, 0.663; P = .002). CONCLUSIONS: In our cohort, 1 in 4 preschool-aged children experienced SJL. Increased sleep duration was associated with increased negative affect, which could have implications for children developing internalizing behavior such as depression or low self-esteem. We found that sleep duration, but not SJL, was associated with temperament and may impact daytime behavior of young children. CITATION: Giannoumis M, Mok E, Borkhoff CM, et al. Association of accelerometry-derived social jetlag and sleep with temperament in children less than 6 years of age. J Clin Sleep Med. 2022;18(8):1993-1999.