Falling asleep earlier was linked to greater weight loss in adults with prediabetes, according to a new study.
An analysis of data from a randomized trial conducted by NYU’s Rory Meyers College of Nursing found that each hour participants fell asleep earlier was associated with weight loss of about 1.3 pounds over eight weeks, although the results did not prove that going to bed earlier led to weight loss.
“When we go to sleep – not just how long we sleep – appears to be an important and overlooked factor in weight loss and metabolic health,” Susan Kohl Malone, an assistant professor in the nursing school and lead author of the study, said in a press release.
The survey, published in the journal Nursing Research, evaluated 196 adults diagnosed with prediabetes and who regularly slept less than 6.5 hours per night.
Half the group participated in an eight-week lifestyle education course on diet, exercise and stress.
The other half received the same training as well as behavioral coaching designed to get them to go to bed earlier, in progressive phases.
Researchers tracked participants’ blood sugar, sleep, and activity using sensors, sleep diaries, and wrist-worn monitors.
Neither group showed significant improvement in blood sugar levels. Both groups lost weight, but those who received sleep coaching didn’t lose significantly more than those who received lifestyle education alone.
“While we expected that extending sleep would improve glucose levels and weight loss in prediabetic adults who sleep for shorter periods, this was not the case in our study,” Malone said.
Participants who received sleep coaching reported better sleep quality and less daytime sleepiness, and they gradually began going to bed earlier.
In a separate analysis of the two groups, participants who changed their sleep earlier tended to lose more weight.
The researchers suggested that the body’s internal clock might help explain these findings.
Staying up late can increase exposure to artificial light, which can activate the body’s stress response and affect hormones that regulate hunger.
Staying up late also coincides with the hours when human insulin sensitivity is at its lowest.
“In contrast, going to sleep earlier may limit late-night eating and better align food intake with the body’s optimal metabolic window,” Malone noted.
The trial only lasted eight weeks, meaning it’s unclear whether participants could maintain earlier bedtimes or maintain weight loss long-term.
While participants wore wrist monitors, key indicators of sleep, such as quality of rest and daytime sleepiness, relied largely on self-reported recordings.
The results also show an association within the study group rather than a proven cause and effect.
Participants receiving sleep coaching fell asleep about 12 minutes earlier on average, according to Malone, which produced no measurable improvement in blood sugar.
The study received funding from the National Institute of Nursing Research, a division of the National Institutes of Health, and was conducted in collaboration with researchers at the University of Delaware.
Gn Health
