OBJECTIVE: Longitudinal studies on night sleep trajectories throughout infancy are sparse. Moreover, most studies have examined samples in Caucasian individuals, although cultural differences in sleep habits have been described. To expand on the current literature, we aimed to determine night sleep trajectories in an Asian population from age 3-24 months.
METHODS: Night sleep duration from a subset of 893 infants within the Growing Up in Singapore Towards healthy Outcomes (GUSTO) birth cohort study was determined using the caregiver-reported Brief Infant Sleep Questionnaire. Latent growth curves were used to analyze sleep trajectories at 3, 6, 9, 12, 18, and 24 months.
RESULTS: The overall trajectory was modeled with a piecewise model with two freely estimated curves. In the first phase (age 3-12 months), infants displayed an average curvilinear increase in night sleep trajectories of 0.12 h per month. In the second phase (age 12-24 months), infants continued to display a curvilinear increase, but at a slower average rate of 0.02 h per month.
CONCLUSIONS: The sleep trajectory of Singaporean infants appeared similar to other predominantly Caucasian cohorts for 3-12 months but not for 12-24 months, in which infants from predominantly Caucasian cohorts mostly displayed a decreasing or a stable-plateaued trajectory. This is in concordance with existing studies that suggest that the underlying influences of night sleep shift from predominantly biological influences to increasing environmental influences with age.