Emergence of racial/ethnic differences in infant sleep duration in the first six months of life.

Objective: Examine the emergence of differences in sleep duration between infants from different racial/ethnic backgrounds and extent to which differences are explained by socioeconomic status (SES) and sleep continuity.

Methods: Sleep duration and continuity (number of night wakings and longest nighttime stretch of sleep) were assessed for 394 infants in the Rise & Sleep Health in Infancy & Early Childhood (SHINE) birth cohort at one- and six-months using the Brief Infant Sleep Questionnaire (BISQ). Multivariable regression was used to estimate associations of race/ethnicity with sleep duration adjusting for individual-level covariates, SES, and sleep continuity.

Results: The sample was 40% non-Hispanic white, 33% Hispanic, 11% Black, and 15% Asian. Mean (SD) durations for daytime, nighttime, and total sleep at one-month were 6.3 (2.0), 8.9 (1.5), and 15.2 (2.7) hours, respectively. Corresponding durations at six-months were 3.0 (1.4), 9.9 (1.3), and 13.0 (1.9) hours. At one-month, Hispanic infants had shorter nighttime sleep than white infants [β: -0.44 h (95% CI: -0.80, -0.08)]. At six-months, Hispanic [β: -0.96 h (-1.28, -0.63)] and Black [β: -0.60 h (-1.07, -0.12)] infants had shorter nighttime sleep than white infants. The near 1-h differential in night sleep among Hispanics resulted in shorter total sleep [β: -0.66 h (-1.16, -0.15)]. Associations across all racial/ethnic groups were attenuated after adjustment for SES at one- and six months. Sleep continuity attenuated associations with nighttime and total sleep duration by 20-60% for Hispanic infants at six-months.

Conclusions: Differences in sleep duration emerge early in life among racial/ethnic groups and are in part explained by SES and sleep continuity.