Want stable blood sugar? Go to bed earlier and sleep longer, study reveals

By Priyanjana Pramanik, MSc.Reviewed by Susha Cheriyedath, M.Sc.Mar 6 2025

Researchers using continuous glucose monitoring uncover how bedtime habits and sleep length directly affect blood sugar stability, highlighting sleep as a powerful tool in managing diabetes risk and metabolic wellness.

Study: Trajectories of Sleep Duration, Sleep Onset Timing, and Continuous Glucose Monitoring in Adults. Image Credit: Tatiana Shepeleva / Shutterstock

In a recent article in JAMA Network Open, researchers explored the relationship between long-term sleeping patterns and blood glucose levels. They aimed to understand whether late sleep timings or inadequate sleep durations negatively impact glucose regulation, a process critical to preventing diabetes and other metabolic diseases.

Their findings indicate that late sleep onset and inadequate sleep are linked to poorer glycemic control, both separately and together. This underscores the role of healthy sleep habits in reducing the risk of diabetes and improving metabolic health.

Background

Sleep is essential for health and well-being; poor sleep, either because of sleeping too late or not getting enough sleep, is linked with several health issues, including weight gain, weakened immunity, and inflammation.

Poor sleep can also negatively affect blood sugar control. While previous studies have linked sleep to fasting blood sugar levels, its effects on daily fluctuations in blood sugar and, thus, diabetes management have not been thoroughly explored.

Advances in continuous glucose monitoring (CGM) technology allow researchers to track blood sugar changes over time, enabling exploration of the long-term impact of sleep patterns on blood sugar dynamics.

About the study

The research team investigated how long-term duration of sleep and sleep timing affect blood sugar control in middle-aged and older adults in Guangzhou, China. They also examined whether late sleep onset and poor sleep duration together contribute to worsened blood sugar regulation, hypothesizing that individuals with late bedtimes and shorter sleep would exhibit the worst glycemic control.

The participants were between 46 and 83 years old and had lived in Guangzhou for five years or more. They wore a CGM device, which collected glucose readings at 15-minute intervals for 14 days. The research team used this data to calculate glucose control metrics, including fluctuations in blood sugar (glycemic variability), the proportion of time an individual’s blood sugar stayed within the normal range of 3.9 to 10 mmol/L (time in range), and the average daily glucose level.

Sleep duration was collected at three points between 2013 and 2023 using self-reported data, while time of sleep onset was collected at two points between 2017 and 2023 and included information about an individual’s typical bedtime and how long it took them to go to sleep. Out of the 2345 participants enrolled at the beginning of the study, 1156 were included for the sleep duration analysis and 1109 for the sleep timing analysis.

Using this data, researchers applied group-based trajectory modeling to explore statistical relationships between sleep quality and glucose regulation. First, they classified participants into different sleep patterns, with four groups based on sleep duration (adequate, mild inadequate, moderate inadequate, and severe inadequate) and two groups based on sleep timing (persistent early sleepers and persistent late sleepers). This data was analyzed using regression models that adjusted for various lifestyle and demographic factors.

Findings

The average age of the participants was 63 years, and 70.6% were women. At baseline, the average sleep duration was 6.9 hours per night, which declined to 6.6 hours during the first follow-up and 6.4 hours during the second follow-up. During the first follow-up, nearly 72% reported sleeping before midnight.

The group with adequate sleep comprised 11.5% of participants and slept for 8-8.4 hours per night. More than 55% reported mildly inadequate sleep (between 6.8 and 7.2 hours per night), while 27.3% slept 5.5-6 hours a night, classified as moderately inadequate. Only 5.7% had severely inadequate sleep (4.1-4.7 hours per night).

Researchers observed that less sleep was significantly associated with higher glycemic variability, with a coefficient of variation of 1.17% higher for mildly inadequate sleepers and 2.87% higher for severely inadequate sleepers; the standard deviation (SD), mean amplitude of glycemic excursions (MAGE), and mean of daily differences (MODD) were also greater. Severely inadequate sleep was also correlated with lower glucose stability, with a 3.11% reduction in the time that blood sugar stayed within the normal range of 3.9-10 mmol/L.

Early sleepers comprised 79.2% of the population, while late sleepers comprised 20.8%. Late sleepers also showed higher glycemic variability, with a 1.18% higher coefficient of variation, as well as a higher SD and MODD.

Regarding the combined impact of sleep duration and sleep timing, those with both inadequate sleep and late sleep onset had the worst glycemic variability, with the highest coefficient of variation, SD, MAGE, and MODD. Late sleepers also had consistently worse glucose variability than early sleepers across all sleep duration categories. However, researchers noted that the subgroup with adequate sleep duration combined with persistent late sleep onset represented only 1.1% of the sample, limiting the reliability and generalizability of conclusions drawn from this group.

Conclusions

In this study, researchers established clear linkages between poor sleeping habits and increased fluctuations in blood sugar levels using long-term tracking methods. Their methods ruled out reverse causality and biases due to cross-sectional designs or single-period measurements. However, the self-reported sleep data may give rise to inaccuracies, and the effects of sleep disorders were not fully considered. Additionally, the study was limited to middle-aged and older Chinese adults, restricting the generalizability of these findings to other age groups or ethnicities.

Ensuring adequate sleep and maintaining an early bedtime can help stabilize blood sugar levels and reduce health risks. These findings highlight sleep as a key factor in glucose management and overall metabolic health.