Sleep and Blood Sugar: Why Your Bedtime Habits Matter More Than You Think

Julene Montgomery
Jul 14
4 min read

The Blood Sugar-Sleep Connection You Can’t Ignore

We often focus on food and exercise when it comes to managing blood sugar, but there’s a quiet powerhouse working behind the scenes: sleep. Whether you’ve been diagnosed with prediabetes or you're just trying to keep your blood sugar steady, sleep plays a much bigger role than most people realize. In this article, we’ll break down the science, bust a few myths, and share simple strategies to help you sleep better—and wake up with more stable blood sugar.

Why Sleep Matters for Blood Sugar

Let’s start with the basics. Your body has an internal clock—your circadian rhythm—that governs everything from hormone production to digestion. When you don’t get enough quality sleep, that rhythm gets disrupted, and your blood sugar takes a hit.

Here’s what poor sleep does:

Increases insulin resistance, making it harder for your cells to use glucose
Elevates cortisol levels, which can raise blood sugar
Disrupts hunger hormones like ghrelin and leptin, leading to more cravings
Reduces your body’s ability to repair and regulate glucose overnight

Even just one night of poor sleep can make your blood sugar more erratic the next day. Imagine what chronic sleep issues can do!

Sleep Deprivation and Prediabetes: The Hidden Link

Several studies have shown that people who consistently sleep less than 6 hours a night have a significantly higher risk of developing prediabetes. One study published in Diabetes Care found that sleep restriction alone (without diet changes) can induce insulin resistance in healthy people.

So if you’ve been dialing in your meals but skipping on rest, your blood sugar may still be out of balance. Think of sleep as a non-negotiable foundation for metabolic health.

How Blood Sugar Affects Your Sleep (Yep, It Goes Both Ways)

The relationship is two-way. Poor sleep worsens blood sugar, but high blood sugar also disrupts sleep. Here’s how:

High blood sugar can cause frequent urination at night, dehydration, and restlessness
Blood sugar crashes (especially from nighttime snacking) can cause you to wake up suddenly or have trouble staying asleep
Low magnesium and B vitamins—common in people with blood sugar issues—can also affect sleep quality

In other words, if you’re tossing and turning, your blood sugar may be part of the reason.

Signs Your Sleep May Be Affecting Your Blood Sugar

You wake up tired even after 7–8 hours
You need caffeine or sugar to “get going” in the morning
You crave carbs or sweets more on days after poor sleep
Your CGM shows higher fasting glucose on days you sleep poorly
You feel more stressed, foggy, or irritable

If any of those sound familiar, it might be time to audit your sleep habits.

Tips for Better Sleep (and Better Blood Sugar)

Stick to a Sleep Schedule Go to bed and wake up at the same time—even on weekends. This strengthens your circadian rhythm and supports stable glucose metabolism.
Watch the Evening Snacking Late-night eating can lead to higher glucose levels overnight. Try to finish meals 2–3 hours before bed.
Create a Blood Sugar-Friendly Dinner Include protein, healthy fats, and fiber to avoid glucose spikes that disrupt sleep.
Ditch the Screens Before Bed Blue light can suppress melatonin, your sleep hormone. Try dimming lights and powering down devices at least 60 minutes before bed.
Get Natural Light Early in the Day Morning sunlight exposure helps regulate cortisol and melatonin, improving nighttime sleep.
Use a CGM or Track Sleep Devices like a CGM (continuous glucose monitor) or the Oura Ring can help you spot patterns between your sleep and glucose trends.
Supplement Smartly Talk to your practitioner about magnesium glycinate, glycine, or inositol—all of which can support sleep and metabolic health.

But What If You’re Doing Everything Right and Still Can’t Sleep?

If you’ve cleaned up your sleep hygiene and still struggle, it’s worth checking for deeper issues:

Sleep apnea: Especially common in people with insulin resistance and belly fat
Restless leg syndrome: Linked to iron or magnesium deficiency
Chronic stress or high cortisol: This may call for stress management strategies like meditation, breathwork, or adaptogens (like ashwagandha or rhodiola)

You’re not failing—your body might just need more targeted support.

What’s the Ideal Sleep Window for Blood Sugar?

While everyone’s needs vary, most adults do best with 7–9 hours of quality sleep. It’s not just quantity—it’s consistency and depth that matter. Deep, uninterrupted sleep is when your body does most of its hormonal repair work.

Sleep between 10 p.m. and 6 a.m. aligns best with natural melatonin and cortisol rhythms, but even if your schedule shifts, try to keep your sleep/wake times stable.

Real Talk: You Can’t Out-Eat or Out-Exercise Poor Sleep

Yes, food and movement matter. But if you’re trying to manage blood sugar without prioritizing sleep, it’s like trying to patch a leaky boat with duct tape.

Your insulin, your hunger cues, your motivation—they all depend on how well you sleep.

So instead of just asking, “What should I eat for better blood sugar?” also ask, “How can I sleep better tonight?”

Final Thoughts: Sleep Is the Unsung Hero of Blood Sugar Balance

If you’ve been focusing on food and exercise but haven’t yet looked at your sleep habits—start there. It’s free, powerful, and something you do every day.

And if you’re supporting someone with prediabetes? Helping them sleep better might be the most loving, effective thing you can do.

Want more info? Check out my YouTube video on how sleep affects blood sugar.

Did you know that a steam sauna can improve blood sugar?

Yes, that’s right! And there are many other easy ways to improve blood sugar. Addressing prediabetes doesn’t have to be hard. Ready to improve your blood sugar without changing your diet? Sign up for my FREE mini course, 10 Ways to Improve Blood Sugar Without Changing Your Diet. It’s a free email course, and it’s a fast and easy way to learn 10 impactful tips to begin balancing your blood sugar TODAY! Learn more