Night-to-night sleep duration and wake-anchored glycemia: associations with continuous glucose monitoring in free-living adolescents.

STUDY

objectivesSleep duration influences metabolic health, but the impact of daily sleep variation on next-day glycaemia in healthy individuals under real-world conditions is poorly understood. MATERIALS AND

methodsWe studied 206 adolescents (18 years) from the Copenhagen Prospective Studies on Asthma in Childhood 2000 cohort with 2245 person-days of overlapping accelerometer-derived sleep and continuous glucose monitoring recordings (median 13 days, IQR 9-13). Sleep duration was assessed using wrist-worn accelerometry, and glycemic concentration, variability, and risk indices were derived from continuous glucose monitoring during the accelerometer-defined waking period. Associations were examined using linear mixed-effects models adjusted for sociodemographic, behavioral, circadian, and cardiometabolic factors, with random effects of individuals across repeated days.

resultsEach additional hour of sleep was associated with higher next-day glycaemic concentration (median β 0.39 mg/dL [0.15, 0.63], p = .002), lower variability (standard deviation (SD) mg/dL β -0.12 [-0.23, -0.01], p = .036), and reduced deviation risk (Average Daily Risk Range, indicating lower risk of extreme glucose excursions; β -0.27 [-0.43, -0.10], p = .002). Within-person deviations in sleep predicted next-day glycaemic concentration and deviation risk, whereas habitual between-person differences were more strongly associated with variability. Higher daytime glycaemic variability predicted shorter subsequent sleep (β -0.11 h [-0.18, -0.05], p < 0.001). The early-morning pre-wake glucose rise partly mediated the link between longer sleep and higher next-day median glucose (indirect effect 5.0%, p = 0.036).

conclusionsThese findings indicate dynamic, bidirectional coupling between sleep and glucose regulation in free-living adolescents, with longer sleep associated with lower next-day glycemic variability and reduced risk of extreme glucose excursions. Statement of Significance Adolescence is a critical period for establishing lifelong sleep and metabolic health patterns, yet real-world links between nightly sleep and glucose regulation remain poorly defined. This study combines accelerometer-derived sleep with continuous glucose monitoring across repeated free-living days in 206 generally healthy adolescents. Wake-anchored analyses showed that longer sleep was associated with modestly higher next-day glycemic concentration, but lower glycemic variability and deviation risk, while greater daytime variability predicted shorter subsequent sleep. A pre-wake glucose rise partly mediated the association between sleep duration and next-day glycemia, suggesting that the transition from sleep to wake may be an important physiological window linking sleep with metabolic regulation.