Irregular Sleep Linked to Severe Metabolic Dysfunction in Black Adults

In addition to irregular sleep duration, later sleep timing and poor sleep continuity are associated with more severe metabolic dysfunction among Black adults, according to study findings published in The Journal of Clinical Endocrinology & Metabolism.

From 2017 to 2020, non-Hispanic Black adults had the highest prevalence of obesity in the United States (49.9%). Black individuals are also disproportionately affected by obesity-related diseases (type 2 diabetes, cardiovascular disease), which are leading causes of preventable deaths.

To examine relationships between sleep domains and metabolic dysfunction among Black individuals, investigators conducted an observational cross-sectional analysis using data from the Jackson Heart Sleep Study (JHSS). Adjustments were considered for age, smoking, physical activity, alcohol use, socioeconomic factors, and moderate to severe obstructive sleep apnea (OSA).

The JHSS sought to evaluate sleep health as risk factors for cardiovascular disease and stroke among Black adults aged 21 to 95 years from the Jackson, Mississippi metropolitan area between 2012 and 2016. Individuals with continuous positive airway pressure use were excluded.

Overall, 754 participants (mean [SD] age, 63.1 [10.7] years; 66.1% women) had:

• Mean (SD) body mass index (BMI) of 31.8 (6.8) kg/m²;
• Mean (SD) sleep onset time of 23:10 (1:24) hh:mm;
• Mean (SD) sleep duration of 6.7 (1.1) h;
• Median (IQR) sleep maintenance efficiency of 88.9% (85.7-91.5); and,
• Median (IQR) sleep fragmentation index of 28.3% (23.2-34.0).

Among the participants, 54.9% had obesity (BMI≥30kg/m²), 80.3% had elevated waist circumference, 86.2% had dysglycemia, 85.0% had hypertension, and 27.7% had diabetes.

Each 1 h increase in sleep duration variability was associated with 34% higher odds of severe metabolic syndrome (MetS; odds ratio [OR], 1.34; 95% CI, 1.01-1.77), and each 1 h later in mid-sleep time was associated with 14% higher odds of severe MetS (OR, 1.14; 95% CI, 1.01-1.30).

Each 1% increase in sleep fragmentation index was associated with 2% higher odds of having severe MetS (OR, 1.02; 95% CI, 1.01-1.04), whereas each 1% increase in sleep maintenance efficiency was associated with 5% lower odds of having severe MetS (OR, 0.95; 95% CI, 0.92-0.98).

Study limitations include the cross-sectional design, absence of dietary data to evaluate interaction between sleep and food, and possible residual confounding.

The researchers concluded that “sleep health is multidimensional beyond sleep duration, with sleep timing, regularity, and continuity contributing to metabolic health in Black individuals… irregular sleep duration, poor sleep continuity, and later sleep timing assessed by actigraphy were each associated with severe MetS, after accounting for sociodemographic and lifestyle factors and the presence of untreated moderate-to-severe OSA.”

This article originally appeared on Endocrinology Advisor