Associations of Sleep Health and Metabolic Syndrome Severity in Black Individuals: The Jackson Heart Sleep Study

Context The influence of sleep and circadian-related factors on metabolic outcomes among Black Americans are under-studied, despite the disparities in both metabolic and sleep health in this population. Objective This work aimed to investigate the relationship between domains of sleep and metabolic dysfunction severity in Black individuals. Methods We conducted a cross-sectional analysis of the Jackson Heart Sleep Study (2012-2016), using logistic regression to assess the associations between actigraphy parameters (sleep timing, duration and regularity, continuity) and severe metabolic syndrome (MetS), defined as the highest tertile of a validated sex-, race-, and ethnicity-specific MetS severity Z score. Models were adjusted for age, socioeconomic factors, physical activity, smoking, alcohol use, and moderate to severe obstructive sleep apnea. Results Among 754 participants (mean age 63 ± 11 years, 66% women, mean body mass index 31.8 ± 6.8), mean sleep onset was 23:10 ± 1:24 (hh:mm), mean sleep duration was 6.7 ± 1.1 hour, median sleep maintenance efficiency was 88.9% (interquartile range [IQR], 85.7-91.5), and median sleep fragmentation index was 28.3% (IQR, 23.2-34). In adjusted models, each 1-hour later in mid-sleep time was associated with 14% (95% CI, 1.01-1.30) higher odds of severe MetS and each 1-hour increase in sleep duration variability was associated with 34% (95% CI, 1.01-1.77) higher odds. Each 1% decrease in sleep maintenance efficiency was associated with 5% (95% CI, 0.92-0.98) higher odds of having severe MetS, and each 1% increase in sleep fragmentation index was associated with 2% (95% CI, 1.01-1.04) higher odds. Conclusion Later sleep timing, irregular sleep duration, and poor sleep continuity were associated with more severe metabolic dysfunction in Black individuals, highlighting the importance of sleep health, beyond sleep duration, on metabolic health.