Ever wondered why a bad night’s sleep leaves you feeling sluggish, irritable or even craving sweets? Turns out, your sleep habits might be doing more than just making you tired—they could be throwing your blood sugar out of balance.
A new study from China’s Westlake Laboratory of Life Sciences and Biomedicine has uncovered a strong link between inadequate sleep and erratic blood glucose levels, a factor that could increase the risk of diabetes and other metabolic disorders.
The sleep-sugar connection
We all know sleep is essential for overall health but researchers have now discovered that both how much you sleep and when you go to bed can significantly impact your body’s ability to regulate blood sugar. Using data from continuous glucose monitoring (CGM), scientists tracked the sleep patterns and blood sugar fluctuations of over 1,100 adults aged 46 to 83 as part of the Guangzhou Nutrition and Health Study.
What they found was eye-opening — people who consistently got less sleep or went to bed late experienced greater fluctuations in their blood sugar levels. This means their bodies struggled more to maintain stable glucose levels, which is crucial for metabolic health and diabetes prevention.
How much sleep do you really need?
Participants in the study were grouped into four sleep categories based on how much rest they got each night:
- Severe inadequate sleep (4–4.7 hours)
- Moderate inadequate sleep (5.5–6 hours)
- Mild inadequate sleep (6.8–7.2 hours)
- Adequate sleep (8–8.4 hours)
Not surprisingly, those who consistently slept the least experienced the biggest blood sugar swings but even people who were not getting quite enough sleep — between 5.5 to 7 hours — showed signs of higher glycemic variability. On top of that, bedtime mattered too.
The study identified two sleep timing groups: early sleepers and late sleepers. Those who stayed up late had a 1.18% higher glycemic variability, while those who both slept fewer hours and went to bed late had the worst blood sugar control of all.
Why does this matter?
Blood sugar fluctuations are not just a concern for people with diabetes—they affect energy levels, hunger cues and overall health. When blood glucose is unstable, it can lead to increased cravings, sluggish metabolism and higher risks of insulin resistance over time.
For those already at risk of diabetes, this research highlights how important it is to not only eat well and exercise but also to prioritise sleep as part of a healthy lifestyle.
How to improve sleep for better blood sugar control
Want to give your metabolism a boost? Try these simple sleep-friendly habits:
- Aim for 7–8 hours of sleep per night – Your body needs this time to regulate hormones and support metabolic function.
- Set a consistent bedtime – Going to bed at the same time each night helps regulate your internal clock.
- Avoid screens before bed – Blue light from phones and TVs can delay melatonin production, making it harder to fall asleep.
- Limit late-night snacks – Eating too close to bedtime can cause glucose spikes that disrupt sleep.
- Get morning sunlight – Exposure to natural light early in the day helps set your circadian rhythm for better sleep at night.
If you are looking to improve your health, do not just focus on diet and exercise—fix your sleep habits too. As this study shows, getting enough rest and maintaining a consistent bedtime could be key to keeping your blood sugar stable and reducing the risk of metabolic issues.
So, the next time you think about staying up late to binge another episode or scroll through social media, consider this: your sleep might be the missing piece in your wellness puzzle.
Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.
