Postdoctoral Research Fellow Hassenfeld Children's Hospital at NYU Langone Brooklyn, New York, United States
Background: Childhood obesity has emerged as a key public health challenge, with increasing focus on prevention during the first two years of life. Researchers have highlighted associations among screen time, sleep duration, and increased weight status in school age and adolescent children. There is a gap in understanding these relationships in the first two years of life, a critical life stage for obesity prevention and risk. Figure 1 displays a conceptual model describing relations between these variables. Objective: Examine the relations between screen time and sleep duration at 12 months old and child weight outcomes at 24 months. Design/Methods: This was a secondary analysis of data from the NYU Children’s Health Environmental Study, a longitudinal pregnancy cohort in New York City. Screen time (TV and tablet) and sleep duration (daytime and night) were derived from questionnaires administered at 12 months. Weight in grams at 24 months was obtained from both electronic health record and questionnaire data. We applied World Health Organization standards to convert weight to weight-for-age z-scores (WFAZ). We controlled for the following covariates: maternal race and ethnicity, insurance type, employment, child assigned sex, parity and household income. We used adjusted linear regressions to assess associations between screen time and sleep duration hours at 12 months old, sleep at 12 months old and WFAZ at 24 months, and finally screen time at 12 months and WFAZ at 24 months. Results: Participants characteristics are presented in Table 1 (n=594). Total screen time at 12 months old is 61.7 minutes, mean total sleep duration at 12 months old was 12.7 hours, and mean WFAZ at 24 months old was 0.76. We detected significant associations between total sleep duration and total screen time hours at 12 months old (B=-0.154 with 95% CI [-0.306, -0.002]. Total sleep duration at 12 months old was also negatively associated with WFAZ at 24 months old (B=-0.040 with 95% CI [-0.079, -0.000]). We did not detect associations between screen time at 12 months and WFAZ at 24 months (B= -0.022 with 95% CI [-0.082, 0.037]).
Conclusion(s): We found that increased total screen time at 12 months was associated with decreased sleep at 12 months. Increased sleep duration at 12 months old was subsequently associated with decreased weight at 24 months old. We did not detect an association between screen time at 12 months and weight at 24 months, future efforts should examine other key variables such as quality of screen time and sleep that were not considered and could be important in understanding further associations.