Glucose homeostasis during recurrent periods of sleep restriction and recovery in healthy young adults.

STUDY

objectivesTo investigate if glucose homeostasis was impaired during recurrent periods of sleep restriction and recovery, and if the impairment was moderated by sleep duration variability across nights.

methodsIn this 16-day laboratory-based study, 48 healthy young adults underwent two baseline nights of 8-h time-in-bed (TIB), followed by two cycles of "weekday" sleep opportunity manipulation (control group's TIB: 8-h/night; stable short sleep group: 6-h/night; variable short sleep group: 8-, 4-, 8-, 4-, and 6-h from the first to fifth night) and "weekend" recovery (all groups: 8-h/night). Plasma glucose and insulin concentrations during fasting and oral glucose tolerance tests (OGTTs) were measured at the end of baseline and each manipulation period.

resultsNo significant group×day interaction on glucose or insulin outcomes was found (p > .15). At 2-h post-glucose load, the control group's glucose levels remained relatively stable in all OGTTs (p > .08), although their insulin levels increased from baseline (p < .02) probably due to sedentariness in the laboratory. The stable short sleep group also showed increased insulin levels in the first week (p = .02), but their glucose levels still increased from baseline (p = .02; Cohen's dz = 0.39). Importantly, in both weeks of sleep restriction, the variable short sleep group failed to significantly elevate their insulin levels (p > .30); hence, their glucose levels increased from baseline (p < .01, dz ≥ 0.99) more prominently than the stable short sleep group.

conclusionsGlucose homeostasis was impaired in healthy young adults after recurrent periods of sleep restriction. Variable and stable short sleep schedules may impair glucose tolerance to different extents and in different pathways. CLINICAL TRIAL: Performance, Mood, and Brain and Metabolic Functions During Different Sleep Schedules (STAVAR), https://www.clinicaltrials.gov/study/NCT04731662, NCT04731662. Statement of Significance Simulating two consecutive work weeks, our study showed that weekday sleep restriction led to decreased glucose tolerance despite intervening weekend recovery sleep. The extents and presentations of glucose tolerance depended on the variability in night-to-night sleep duration: the stable short sleep group experienced early signs of insulin resistance with compensatory insulin hypersecretion and small elevation in glucose concentrations, while the variable short sleep group experienced possible beta cell functional impairment, resulting in an absence of significant compensatory insulin hypersecretion and prominent increases in glucose levels. Critically, having a time-in-bed within the age-specific recommended range every night appeared to be the only way to optimize glucose tolerance, thereby minimizing the risk for type 2 diabetes mellitus.