Longitudinal associations of sleep curtailment with metabolic risk in mid-childhood.

Objective: To examine associations of chronic insufficient sleep with mid-childhood cardiometabolic health.

Methods: At 6 months and yearly from 1 to 7 years, mothers participating in the Project Viva cohort reported children's 24-h 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 five 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 (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.