Adults diagnosed with prediabetes who shifted their bedtime earlier experienced slightly greater weight loss over an eight‑week period, according to a new analysis of data from a randomized trial led by the NYU Rory Meyers College of Nursing.
Study design and participants
The investigation, published in Nursing Research, enrolled 196 participants who regularly slept fewer than 6.5 hours per night. Researchers divided the cohort into two equal groups. One half completed an eight‑week lifestyle education program covering diet, exercise and stress management. The other half received the same curriculum plus behavioral coaching aimed at gradually moving their bedtime earlier.
Throughout the trial, participants wore wrist‑mounted monitors and kept sleep logs. Sensors tracked blood‑sugar levels, activity and sleep patterns. The study was funded by the National Institute of Nursing Research, a branch of the National Institutes of Health, and involved collaborators from the University of Delaware.
Results on weight and glucose
Both groups lost weight during the eight weeks, but the addition of sleep‑timing coaching did not produce a statistically significant advantage over lifestyle education alone. Neither group showed meaningful improvements in blood‑sugar measurements.
When researchers examined the combined data across both arms, they observed a correlation between earlier sleep onset and greater weight loss. Specifically, each hour participants fell asleep earlier was associated with an average loss of about 1.3 pounds over the study period. Participants who received sleep coaching reported falling asleep roughly 12 minutes earlier on average and also noted better sleep quality and reduced daytime drowsiness.
Potential mechanisms and limitations
The authors suggested that circadian timing may help explain the association. Late‑night exposure to artificial light can trigger stress responses and alter hormones that regulate hunger. Moreover, insulin sensitivity naturally declines in the late evening, so eating later may be less efficiently processed. By sleeping earlier, individuals might limit late‑night snacking and align food intake with a more favorable metabolic window.
Despite these observations, the study does not establish a causal link between bedtime and weight loss. The trial lasted only eight weeks, leaving open questions about the durability of earlier bedtimes and sustained weight change. Additionally, while wrist monitors captured some sleep metrics, key outcomes such as sleep quality and daytime alertness relied heavily on self‑reported logs.
Lead author Susan Kohl Malone, an assistant professor at NYU’s nursing college, emphasized that the timing of sleep—rather than total sleep duration—appears to be an overlooked factor for metabolic health. She noted that the expected improvements in glucose control did not materialize, underscoring the need for further research to clarify the relationship between sleep timing, weight management and blood‑sugar regulation.
Overall, the findings add to a growing body of evidence that circadian alignment may influence weight outcomes, but they also highlight the complexity of translating modest sleep‑timing shifts into clinically meaningful benefits for people with prediabetes.
Mitchell Landsberg is a Senior Technology Correspondent at News Raise. He covers consumer electronics, artificial intelligence, software developments, and digital privacy trends.
