Early Bedtime Linked to Weight Loss in Adults With Prediabetes

Falling asleep earlier has been associated with greater weight loss in adults with prediabetes. New research from NYU Rory Meyers College of Nursing highlights this connection. Participants who fell asleep an hour earlier lost around 1.3 pounds over eight weeks. This finding does not imply causation, but it suggests the timing of sleep may influence weight loss and metabolic health.

When we fall asleep— not just how much we sleep— seems to be an important and overlooked factor for weight loss and metabolic health, said Susan Kohl Malone, assistant professor and lead author of the study.

The study, appearing in Nursing Research, evaluated 196 adults with prediabetes. All participants had less than 6.5 hours of sleep nightly. They were divided into two groups. One attended an eight-week lifestyle education course on diet, exercise, and stress. The other received the same course, plus behavioral coaching to progressively move their bedtimes earlier.

Researchers monitored participants’ blood sugar, sleep, and activity with sensors, sleep logs, and wrist-worn devices. Neither group had significant blood sugar improvements. The weight loss was consistent across both groups. However, those with sleep coaching reported better sleep quality and less daytime drowsiness.

Body’s Internal Clock and Behavior

The researchers posited that the body’s internal clock might contribute to these findings. Staying up late exposes individuals to artificial light, potentially activating the body’s stress response and affecting hunger-regulating hormones. The study projected that moving bedtime earlier by 60 minutes could account for roughly 1.3 pounds of weight loss over eight weeks.

A later bedtime also aligns with periods of reduced insulin sensitivity, which can lead to late-night eating. In contrast, an earlier sleep schedule may reduce late-night food consumption and sync food intake with optimal metabolic conditions.

The trial lasted for eight weeks, leaving questions about the sustainability of the changes. Participants relied on self-reported logs for key sleep metrics, affecting the study’s conclusions on rest quality and drowsiness.

The research was funded by the National Institute of Nursing Research, part of the National Institutes of Health. It involved collaboration with the University of Delaware.