Associations of sleep-related behaviors and the sleep environment at infant age one month with sleep patterns in infants five months later.

Objective: To characterize family and environmental correlates of sleep patterns that may contribute to differences in infant sleep.

Methods: We studied 313 infants in the Rise & SHINE (Sleep Health in Infancy & Early Childhood study) cohort. Our main exposures were the parent-reported sleep environment, feeding method and sleep parenting strategies at infant age one month. The main outcomes were nighttime sleep duration, longest nighttime sleep and number of awakenings measured by actigraphy at age six months. We used multivariable linear regression models to examine associations, and secondarily also explored the role of sleep-related environmental exposures in mediating previously observed associations of racial/ethnicity and parental education with infant sleep characteristics.

Results: In adjusted models, a non-dark sleep environment (versus an always dark sleep location) and taking the baby to parent's bed when awake at night (versus no co-sleeping) were associated with 28 (95% CI, -45, -11) and 18 (95% CI, -33, -4) minutes less sleep at night, respectively. Bottle feeding at bedtime was associated with 62 (95% CI, 21, 103) minutes additional longest nighttime sleep period. Exploratory mediation analyses suggested a modest mediating role of a non-dark sleep environment on racial/ethnic and educational differences in sleep duration.

Conclusions: Infant sleep duration was positively associated with a dark sleep environment and a focal feed at bedtime while taking the baby to the parent's bed was associated with reduced infant sleep. Modifying the sleep environment and practices may improve infant sleep and reduce sleep health disparities.