An eight-week study involving nearly 200 adults found that falling asleep earlier was linked to greater weight loss, highlighting the importance of sleep timing in managing body weight.
Going to bed earlier may do more than help people feel fresh in the morning. A new study has found that people with prediabetes who fall asleep earlier may experience greater weight loss, suggesting that sleep timing could play an important role in weight management.
The study, published in the journal Nursing Research, involved nearly 200 adults with prediabetes who slept for less than 6.5 hours every night. Researchers examined how changes in sleep habits affected weight loss over an eight-week period.
Participants were randomly divided into two groups. Both groups followed a lifestyle improvement programme that included healthy eating, physical activity and stress management through weekly video calls. However, one group also received additional sleep coaching.
The coaching focused on improving sleep hygiene, following a regular sleep schedule, gradually moving bedtime earlier and developing healthier sleep habits. Participants maintained daily sleep diaries and wore wrist monitors to track their sleep patterns. Continuous glucose monitors were also used to measure blood sugar levels.
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The findings showed that participants in both groups experienced improvements in sleep and weight. However, those who received sleep coaching reported better sleep quality and less daytime sleepiness.
Interestingly, falling asleep earlier was linked to greater weight loss, regardless of the group participants belonged to. Each hour earlier that participants fell asleep was associated with approximately 1.3 pounds (0.73 kg) of weight loss over eight weeks.
Susan Kohl Malone, assistant professor at New York University’s College of Nursing and the study’s lead author, said, “When we fall asleep – not just how much we sleep – seems to be an important and overlooked factor for weight loss and metabolic health.”
Researchers believe that going to bed earlier may reduce late-night snacking, limit exposure to artificial light and help the body’s natural metabolic processes. Sleep timing may also influence hormones linked to hunger, appetite and stress.
However, the study did not find significant improvements in participants’ blood sugar levels during the programme.
The researchers suggest that maintaining an earlier and consistent bedtime could support weight management, particularly among people with prediabetes. However, it should complement, not replace, healthy eating, regular exercise and medical advice.
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