Earlier Bedtimes Linked To Weight Loss

A new analysis suggests that the timing of sleep may influence weight management for adults with prediabetes. Researchers from the NYU Rory Meyers College of Nursing found that participants who fell asleep earlier experienced greater weight loss over an eight-week period. However, the data indicates an association rather than a direct cause and effect relationship between bedtime and metabolic changes.

The study evaluated 196 adults who typically slept fewer than 6.5 hours per night. The participants were divided into two groups. One group completed a standard eight-week lifestyle education course covering diet, exercise, and stress management. The second group received the same training plus behavioral coaching designed to shift their bedtimes earlier in gradual phases. All participants wore wrist monitors and kept sleep logs to track their activity and rest.

The financial and health metrics showed mixed results. Both groups lost weight, but the cohort receiving sleep coaching did not shed significantly more pounds than the control group. Neither group achieved significant improvements in blood sugar levels. Despite this, the sleep-coached participants reported better sleep quality and reduced daytime drowsiness. On average, this group went to bed approximately 12 minutes earlier than before the intervention.

Susan Kohl Malone, the study’s lead author and an assistant professor at the nursing college, explained that the body’s internal clock likely plays a role in these outcomes. She noted that staying up late increases exposure to artificial light, which can trigger stress responses and alter hunger hormones. Additionally, late-night hours coincide with the time when human insulin sensitivity is at its lowest. Malone stated that falling asleep earlier may limit late-night eating and better align food intake with the body’s optimal metabolic window.

When researchers analyzed the data across both groups, a pattern emerged. Each additional hour of earlier sleep was associated with approximately 1.3 pounds of weight loss over the eight-week trial. Malone acknowledged that while extending sleep was expected to improve glucose levels and weight loss for short-sleeping adults, the study did not confirm those expectations for blood sugar.

The trial was funded by the National Institute of Nursing Research, a division of the National Institutes of Health, and conducted in collaboration with the University of Delaware. The results were published in the journal Nursing Research. The study noted that key sleep metrics such as rest quality relied heavily on self-reported logs rather than objective measurement alone. The eight-week duration leaves questions about long-term sustainability of earlier bedtimes and weight loss.

Malone emphasized that when the body falls asleep, not just the duration of sleep, appears to be an important factor for metabolic health. The research suggests that shifting sleep schedules could be a simple adjustment for some individuals, though it does not guarantee a change in blood sugar control.