Longitudinal Associations of Sleep Curtailment with Metabolic Risk in Mid-Childhood

OBJECTIVE: To examine associations of chronic insufficient sleep with mid-childhood cardio-metabolic health. DESIGN AND METHODS: At 6 months and yearly from 1–7 years, mothers participating in the Project Viva cohort reported children’s 24-hour sleep duration. The main exposure was a sleep curtailment score, ranging from 0 (maximal curtailment) to 13 (never having curtailed sleep). The main outcome was a mid-childhood metabolic risk score, derived as the mean of 5 sex- and cohort-specific z-scores for waist circumference, systolic blood pressure, HDL cholesterol (scaled inversely), and log-transformed triglycerides and HOMA-IR; higher scores indicate higher risk. RESULTS: The mean (standard deviation [SD]) sleep score was 10.0 (2.8); 5.1% scored 0–4, 13.9% scored 5–7, 14.1% scored 8–9, 28.7% scored 10–11, and 38.3% scored 12–13. Mean (SD, range) metabolic risk score was −0.03 (0.6, −1.8 to 2.6). In multivariable models, the metabolic risk score difference for children with most versus least curtailed sleep was 0.29 units (95% Confidence Interval [CI]: 0.02, 0.57). Further adjustment for mid-childhood BMI-z score attenuated this difference to 0.08 units (95% CI: −0.14, 0.30). CONCLUSIONS: Chronic insufficient sleep from infancy to school-age was associated with higher mid-childhood metabolic risk. This association was explained by sleep duration’s influence on mid-childhood adiposity.