Joint Association of Sleep and Physical Activity with Central Obesity in Chinese Adults

OBJECTIVE: To examine the associations of sleep duration and physical activity (PA) with central obesity among Chinese adults. METHODS: Based on the Prediction for Atherosclerotic Cardiovascular Disease Risk in China (China-PAR) project, 175,373 observations from 106,518 participants were included. Generalized estimating equations quantified the associations of sleep duration and PA with waist circumference (WC) and central obesity. Stratified and joint analyses were performed to evaluate combined effects, and an isotemporal substitution model was used to assess substitution effects. RESULTS: Suboptimal sleep duration (< 7 h/day or ≥ 9 h/day) and inadequate PA were associated with higher WC and an increased risk of central obesity. Compared with optimal sleep duration (7 - < 9 h/day), both longer (≥ 9 h/day) and shorter (< 7 h/day) sleep durations were associated with increased WC (0.27 cm [95% confidence interval ( CI): 0.18, 0.35] and 0.15 cm [95% CI: 0.04, 0.27], respectively) and a higher risk of central obesity (odds ratio, 1.09 [95% CI: 1.07, 1.12] and 1.05 [95% CI: 1.02, 1.08], respectively). Joint analyses revealed that individuals with inadequate PA and short sleep duration had the highest WC and highest risk of central obesity. Among individuals sleeping > 8 h/day, substituting 30 min/day of sleep with moderate-to-vigorous PA significantly reduced the risk of central obesity. CONCLUSION: Suboptimal sleep duration has a detrimental effect on central obesity, and adequate PA can mitigate this effect. The impact of reallocating sleep duration varies by sleep duration, highlighting the need to optimize both PA and sleep patterns in China.