THE ARISING · Longevity & Healthspan
Earlier Bedtime Linked to More Weight Loss in Prediabetes Sleep Trial
Adding sleep coaching did not significantly improve blood sugar or weight loss compared with lifestyle coaching alone. An exploratory analysis linked earlier sleep onset with greater weight loss.
The finding comes from a randomized controlled trial of 196 adults with A1c-confirmed prediabetes and short sleep confirmed by wrist-worn activity monitors, published in the journal Nursing Research in 2026. Susan Kohl Malone and colleagues compared a lifestyle program with the same program plus a sleep intervention.
Short sleep is a modifiable barrier to diabetes prevention, the authors write. Yet no adequately powered trial had tested whether building a behavioral sleep intervention into a lifestyle program improves blood sugar or weight loss in this group.
Both programs lasted eight weeks and were delivered one-on-one by video call. Before and after, participants spent two weeks at home wearing a continuous glucose monitor and an activity monitor that estimates sleep. The main outcome was the share of time sensor glucose sat above 140 mg/dL.
On that outcome, the two groups did not differ significantly. Both groups slept more and lost weight by the end, with no significant difference between them on either measure.
The sleep group did report gains the lifestyle-only group did not match. Their self-reported sleep quality and daytime sleepiness improved significantly more. Their sleep onset also moved earlier, a change that was significant only in the sleep group, although the difference between groups did not reach statistical significance.
The weight result came from a post hoc analysis, meaning it was run after the main results, across all participants regardless of group. Earlier sleep onset was independently associated with greater weight loss. Changes in sleep duration were not.
According to Medical Xpress, which covered the study for NYU, each hour earlier that people fell asleep was associated with about 1.3 pounds (0.6 kilograms) of weight loss over the eight weeks.
"When we fall asleep—not just how much we sleep—seems to be an important and overlooked factor for weight loss and metabolic health," Malone said, as quoted by Medical Xpress. She also told the outlet that falling asleep earlier may limit late-night eating and better align food intake with the body's optimal metabolic window.
The authors write that circadian timing, the body's daily rhythm, is a promising and modifiable target for diabetes prevention. They call for prospective trials designed to test sleep timing interventions on metabolic outcomes, and those trials are the next thing to watch.