Whose sleep matters? Untangling the relationships between maternal sleep, child sleep, and maternal depressive symptoms in the first two years of life.

Infants frequently experience sleep problems in early childhood. Poor infant sleep can impact not only infants' cognitive development but also maternal sleep and maternal mental health. Studies have reported associations between infant sleep and maternal sleep and between infant sleep and maternal depression. However, methods utilized in these studies are unable to disentangle the directionality of these relationships. The purpose of this study was to assess the bi-directional relationships between child sleep, maternal sleep, and maternal depression in the first two years of life in a multi-ethnic Asian cohort. Data were drawn from the Growing Up in Singapore Towards healthy Outcomes (GUSTO) cohort. Child nighttime sleep duration, maternal sleep (PSQI), and maternal depression scores (BDI) were assessed at 26 weeks gestational age, and when the child was 3, 12, and 24 months old in 1,131 children. We used autoregressive latent trajectory modeling with structured residuals (ALT-SR) to assess associations. Higher maternal depression scores at 3 months were predictive of longer nighttime sleep duration when the child was 12 months (BDI → ChildSleep:Ѱ = 0.04, p = .01), but at other timepoints this cross-lagged relationship was not significant, (BDI → ChildSleep: Ѱ = 0.02, p = .49; BDI → ChildSleep: Ѱ = 0.03, p = .07). In addition, better maternal sleep at 3 months predicted longer nighttime child sleep duration at 12 months (PSQI → ChildSleep: Ѱ = - 0.08, p = 0.01), but not at other timepoints (PSQI → BISQ: Ѱ = -0.06, p = .29; PSQI → ChildSleep: Ѱ = -0.05, p = 0.18). When using methods that properly differentiate between-person and within-person effects, we found that higher maternal depression scores were protective of infant sleep, but infant sleep did not affect maternal sleep or depression scores.