Alignment Between 24-h Light-Dark and Activity-Rest Rhythms Is Associated With Diabetes and Glucose Metabolism in a Nationally Representative Sample of American Adults

OBJECTIVE The alignment between environmental stimuli (e.g., dark, light) and behavior cycles (e.g., rest, activity) is an essential feature of the circadian timing system, a key contributor to metabolic health. However, no previous studies have in-vestigated light-activity alignment in relation to glycemic control in human populations. RESEARCH DESIGN AND METHODS The analysis included 7,000 adults (aged 20–80 years) from the National Health and Nutrition Examination Survey (NHANES) (2011–2014) with actigraphy-mea-sured, multiday, 24-h activity and light data. We used phasor analysis to derive phasor magnitude and phasor angle, which measures coupling strength and phase difference between the activity-rest and light-dark cycles, respectively. We used multinomial logistic regression and multiple linear regression to study pha-sor magnitude and phasor angle in relation to diabetes (primary outcome) and multiple secondary biomarkers of glycemic control. RESULTS Lower alignment strength (i.e., a shorter phasor magnitude) and more delayed activity relative to the light cycle (i.e., a larger phasor angle) were both associated with diabetes. Specifically, compared with individuals in the quintiles indicating the most proper alignment (Q5 for phasor magnitude and Q1 for phasor angle), those in the quintiles with the most impaired alignment had a >70% increase in the odds of diabetes for phasor magnitude (odds ratio 1.76 [95% CI 1.39, 2.24]) and for phasor angle (1.73 [1.34, 2.25]). Similar associations were observed for bi-omarkers for glucose metabolism. The results were generally consistent across di-verse sociodemographic and obesity groups. CONCLUSIONS The alignment pattern between 24-h activity-rest and light-dark cycles may be a critical factor in metabolic health.