Early Bedtime Linked to Weight Loss in Prediabetic Adults

Research from NYU Rory Meyers College of Nursing suggests that going to bed earlier is associated with weight loss among individuals with prediabetes. The findings, published in the journal Nursing Research, reveal that integrating sleep coaching into a diabetes prevention programme has beneficial effects on participants’ sleep quality and daytime alertness, although it did not alter blood sugar levels.

Susan Kohl Malone, assistant professor and lead author of the investigation, emphasised the need to consider not only the quantity of sleep but also its timing. "When we fall asleep—not just how much we sleep—seems to be an important and overlooked factor for weight loss and metabolic health," she stated.

Previous studies have indicated that inadequate sleep, which includes getting less than seven hours per night or irregular sleep patterns, is linked to weight gain and poor glucose regulation. Insufficient sleep raises stress hormone levels like cortisol, leading to insulin resistance and increased hunger due to shifts in appetite hormones. Conversely, later bedtimes are often associated with late-night eating, a period when the body’s insulin sensitivity and glucose tolerance are at their nadir.

In light of this, the research team aimed to clarify the role of sleep health in the context of diabetes prevention. They conducted a randomised controlled trial involving 196 adults aged between 21 and 64, all of whom reported sleeping less than 6.5 hours each night. Participants were assigned to either an eight-week lifestyle programme or the same programme augmented with sleep strategies.

Weekly video sessions covered healthy eating, physical activity, and stress management tailored towards diabetes prevention. The lifestyle-plus-sleep group benefited from additional sessions concentrating on sleep hygiene, reconditioning their perception of the bed as a sleep cue, and gradually shifting their bedtimes to enhance overall sleep duration. Daily sleep diaries were maintained throughout the trial.

Prior to and following the intervention, participants used continuous glucose monitors to assess glucose levels, alongside wrist monitors to track sleep patterns. The outcomes indicated that neither programme led to modifications in glucose levels. However, improvements in sleep and weight loss were observed in both groups, with the lifestyle-plus-sleep cohort reporting enhanced sleep quality and reduced daytime sleepiness.

Researchers noted a significant shift towards earlier bedtime for participants in the lifestyle-plus-sleep group. An analysis of all participants revealed that earlier sleep onset correlated with greater weight loss, independent of total sleep duration. For every hour individuals fell asleep earlier, they lost approximately 1.3 pounds over the eight-week period.

The study's authors propose several explanations for this correlation, asserting that staying awake late may lead to increased exposure to artificial light, heightened sympathetic nervous system activity, and elevated levels of the “hunger hormone” ghrelin, promoting greater appetite.

Malone remarked, "While we expected that extending sleep would improve glucose levels and weight loss in adults with prediabetes who sleep for shorter periods, this wasn’t the case in our study. However, our findings do raise the possibility that earlier sleep onset, independent of sleep duration, could be a promising target for improving metabolic health."