NYU study of 196 adults with prediabetes: earlier sleep onset linked to 590 g weight loss
In an eight-week study, each hour of earlier sleep onset was associated with about 590 g of weight loss; the authors stress it is a statistical link, not proof of cause.
Researchers at the Rory Meyers College of Nursing, New York University (NYU), found that adults with prediabetes who fell asleep earlier tended to lose more weight over eight weeks, according to c14.co.il, which cites a paper in the journal Nursing Research. Each hour of earlier sleep onset was associated with a loss of about 590 g. c14.co.il
c14.co.ilc14.co.ilOpen source ↗ The authors stress that this is a statistical association and not proof that going to bed earlier caused the weight loss.
Study design
The analysis covered data from 196 adults diagnosed with prediabetes who usually slept less than six and a half hours a night. The researchers wanted to test whether better sleep habits, and earlier sleep onset in particular, affect body weight and metabolic indicators.
Participants were split into two groups for eight weeks. The first took part in a healthy-lifestyle program covering diet, physical activity and stress management. The second received the same program plus behavioral coaching meant to shift sleep onset earlier step by step.
The team tracked participants with blood glucose sensors, sleep diaries and wrist bracelets that recorded sleep and physical activity patterns. c14.co.il
c14.co.ilc14.co.ilOpen source ↗
Results and limitations
Both groups lost weight, but there was no significant difference between the coached participants and those who received only the lifestyle program. Blood glucose levels did not improve significantly in either group. When the researchers analyzed all participants together, those who fell asleep earlier tended to lose more weight, with about 590 g per hour of earlier onset.
Participants who received sleep coaching reported better sleep quality and less daytime sleepiness. They did move sleep onset earlier, but by only about 12 minutes on average, a change that did not lead to a measurable improvement in glucose.
The authors suggest the circadian clock, which helps regulate metabolism and hormone secretion, as one possible explanation. Staying awake late may prolong exposure to artificial light, affect the stress response and disrupt hormones linked to hunger. Late-night hours also coincide with lower insulin sensitivity, and an earlier bedtime might reduce night eating and bring meals closer to the hours when the body handles food better. c14.co.il
c14.co.ilc14.co.ilOpen source ↗
Lead researcher Susan Malone of NYU said that when we fall asleep, and not only how long we sleep, appears to be an important and often overlooked factor in weight loss and metabolic health. She added that the results did not fully match expectations: the team had hoped that longer sleep in short-sleeping adults with prediabetes would improve glucose and weight, and this did not happen.
The authors list several limitations. The study lasted only eight weeks, so it is unclear whether participants can keep an earlier bedtime or whether the association persists over time. Some sleep measures, including rest quality and daytime sleepiness, relied on self-reports. And the fact that people who went to bed earlier lost more weight does not show that the earlier bedtime was the cause.
