FALLING ASLEEP AFTER MIDNIGHT COULD RAISE YOUR DIABETES RISK, NEW STUDY SAYS
If you typically fall asleep well after midnight, it may be time to change your routine.
Reviewed by Dietitian Annie Nguyen, M.A., RDKey Takeaways
- A new study in JAMA Network Open found that your bedtime and how long you sleep can affect your blood sugar.
- Study participants who didn’t get enough sleep or who fell asleep after midnight had increased glycemic variability.
- Glycemic variability, or how much your blood sugar peaks and falls during the day, is a risk factor for diabetes and diabetes-related complications.
Despite the importance of a good night’s sleep, almost 40% of U.S. adults ages 45 to 64 aren’t getting enough of it. How much sleep you need changes throughout your lifespan—babies, kids and teens need more sleep than adults, who require an average of seven hours of sleep a night.
Sleep quality counts, too. If you have a sleep condition that interferes with sleep—like obstructive sleep apnea—you can get enough hours of sleep, but the OSA reduces sleep quality while increasing your risk of heart disease, high blood pressure, stroke, heart rhythm abnormalities and metabolic syndrome.
We’ve previously reported how irregular circadian rhythms, which are closely related to sleep patterns, have been linked with a whopping 300% increased risk of heart disease. And now a new study, published today in JAMA Network Open, looks at how sleep patterns affect blood sugar levels—especially when it comes to how long you sleep and when you go to bed. Here’s what they found.
Related: These 8 Things Could Increase Your Prediabetes Risk, According to Experts
How Was This Study Conducted?
Researchers in China wanted to know if and how sleep patterns affect blood glucose (sugar) levels in the general population—those without diabetes. They drew their data from a long-term, ongoing study called the Guangzhou Nutrition and Health Study, which included Chinese participants ages 40 to 75. Participants completed follow-up assessments every three years.
From the total study population, researchers pulled out a smaller cohort of 1,156 individuals who had complete sleep and blood glucose information. This group consisted mostly of women (71%) with an average age of 63 at baseline. This cohort’s baseline was their follow-up visit for the main study between 2014 and 2017. During this time, participants reported on their sleep habits.
Sleep duration—how many hours a night on average—was assessed at three time points: baseline (2013-2017), first follow-up (2017-2021) and second follow-up (2021-2023).
Sleep onset was assessed during two follow-up visits—the first follow-up (2017-2021) and the second (2021-2023). For sleep onset, participants were asked to report their typical bedtime and how long it took them to fall asleep.
Participants in this cohort also wore a continuous glucose monitoring device for 14 consecutive days. A CGM is a small disc worn on the back of the arm that monitors blood sugar levels, records the results and sends them to a smartphone, smartwatch or computer. It takes the place of having to prick your finger and use a blood sample. A CGM measures glucose levels every 15 minutes.
Related: 5 Things to Do When You Wake Up for Better Blood Sugar, According to Dietitians
What Did This Study Find?
After researchers ran several statistical analyses, including adjusting for potential confounders—like age, BMI, physical activity, tea and coffee consumption and more—several findings surfaced.
- Participants with inadequate sleep duration and improper timing of sleep—alone and in combination—exhibited larger glycemic variability.
- Both severe and mild inadequate sleep were associated with higher glycemic variability compared to adequate sleep.
- Those who fell asleep after midnight had increased glycemic variability.
Glycemic variability is how much blood glucose levels vary and go up and down. Ideally, they stay within a certain range and show stability. When there is a lot of glycemic variability, it means the person is probably experiencing more extreme highs and lows in their glucose levels. According to these study authors, glycemic variability is a risk factor for chronic disease and early death.
Related: The #1 Habit to Start for Better Blood Sugar, According to Dietitians
How Does This Apply to Real Life?
Essentially, this study found that people who don’t get enough sleep and/or go to bed late have greater fluctuations—highs and lows—in their blood sugar levels. Those fluctuations can be a risk factor for developing type 2 diabetes. And, as the study authors point out, the connection between blood glucose and sleep makes a lot of sense.
The researchers note that previous studies have suggested that chronic sleep insufficiency can activate inflammatory pathways and exacerbate glycemic abnormalities. Growth hormone, which is sleep-dependent, also affects glucose metabolism. And delayed sleep onset disrupts the circadian rhythm, which affects glycemic health by causing shifts in hormone release patterns—like cortisol and melatonin—and increasing compounds that encourage inflammation in the body.
Chronic inflammation is a culprit in many diseases. The kicker is that inflammation has a bidirectional relationship with sleep. That means that a lack of sleep can cause inflammation, but inflammation can also disrupt sleep, interfering with sleep duration and depth and causing wakefulness.
Related: The 7 Best Condiments for Better Blood Sugar, According to Dietitians
We also previously reported on how irregular sleep can increase diabetes risk by up to 35%—and this current study adds to the growing amount of evidence supporting this. What’s really interesting about this study is that going to bed late negatively affected blood glucose levels, even if those individuals got the recommended amount of sleep. This goes hand-in-hand with the evidence surrounding circadian rhythms and disease risk.
So what does this mean for you? Simply put: Go to bed earlier, aim for seven hours of sleep each night and make sure it’s quality sleep. If you snore or are getting enough sleep but are still exhausted, make an appointment with your primary care practitioner. They’ll review your symptoms and can refer you to the appropriate specialists.
There are several things you can do to help get a better night’s sleep, starting with establishing a bedtime routine at least an hour before your head hits the pillow. Ditch your devices, use white noise or a fan, and make sure that your bedroom is cool enough and that your sheets and mattress are cooling and comfortable.
Include foods throughout your day that can help you sleep better at night, like pistachios, salmon, milk and eggs. And avoid caffeine, alcohol and added sugar too close to bedtime.
Related: I Tried a Doctor-Recommended Sleep Routine for 2 Weeks—Here’s What Happened
If your mind tends to jump on the hamster wheel as soon as your head hits the pillow, take some time to journal before bedtime. This includes practicing gratitude—write down what you’re thankful for from that day, even if it’s being thankful for the lessons you learned from dealing with the day’s challenges. Research suggests that engaging in this type of positive psychological strategy—which includes practicing gratitude—can improve sleep.
The Bottom Line
This study suggests that not getting enough sleep and going to bed late—alone and in combination—are associated with larger spikes and dips in blood sugar in people without diabetes. This increases the risk of inflammation and chronic disease, including metabolic syndrome. Study authors stress the importance of getting enough sleep and going to bed earlier. It’s also important to improve the quality of your sleep. And if you feel you’re doing all you can to get plenty of quality sleep but are still exhausted, it’s time to visit your primary care practitioner.
Related: I Have Diabetes and I Tried Eating Only Plants for Two Weeks—Here’s What Happened
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2025-03-05T21:16:50Z