Relationship Between Sleep and Meal Timing with Glycemia Parameters in Individuals with Obesity Participating in a Randomized Time-Restricted Eating Study.

Background/Objectives: Circadian misalignment, including mistimed sleep or eating, is associated with altered glucose metabolism. The importance of eating window timing for time-restricted eating (TRE) is increasingly recognized. This secondary analysis examined associations between meal to sleep timing intervals and glycemic parameters in individuals with obesity across three dietary interventions [TRE, CR: caloric restriction, and UE: unrestricted eating]. Methods: Participants aged 18-65 years with obesity were randomized to a 12-week intervention: TRE (8 h eating window), CR (15% reduction in daily caloric intake), or UE (usual eating habits). CGM and actigraphy were assessed over two weeks at baseline and end-intervention. Mixed effects models examined associations between continuous glucose monitoring (CGM) outcomes and two intervals: last meal to sleep onset (PM meal-Sleep) and awakening to first meal (Awake-AM meal). Results: Each hour increase in the Awake-AM meal interval was associated with lower overnight (1 AM-5 AM) average glucose, lower glycemic variability, lower %time > 180 mg/dL, and greater %time < 70 mg/dL. Each hour increase in the PM meal-Sleep interval was associated with lower overnight (1 AM-5 AM) average glucose. Both associations persisted after adjustment for baseline sleep duration, HbA1c, and randomization assignment. Conclusions: In individuals with obesity, morning (Awake-AM meal interval) and evening (PM meal-Sleep interval) fasting relative to sleep were differentially associated with glycemic control. These findings highlight the relevance of eating and sleep timing to glycemic parameters and may inform eating window selection for individuals practicing TRE.