Waking up to unexpectedly high blood sugar levels—even without having eaten—can be both puzzling and frustrating.

For many people with diabetes or prediabetes, this early-morning rise is a familiar challenge. The main cause? A process known as the dawn phenomenon.

Let’s take a closer look at what it is, why it happens, and how you can keep it under control.

What is the Dawn Phenomenon?

The dawn phenomenon is a natural rise in blood sugar that typically happens between 2 a.m. and 8 a.m. It occurs in everyone, but for those with diabetes, the effect is stronger and more difficult to manage.

Why Does It Happen?

Your body follows a built-in 24-hour schedule called the circadian rhythm. As morning approaches, it begins preparing to wake you up by releasing certain hormones:

• Cortisol

• Growth hormone

• Epinephrine (adrenaline)

• Glucagon

These hormones tell the liver to release stored glucose into the bloodstream, providing the energy needed to start the day. In people without diabetes, the pancreas balances this rise by producing extra insulin.

For those with diabetes or insulin resistance, the body either doesn’t make enough insulin or the insulin isn’t as effective. The result is a noticeable and prolonged rise in blood sugar.

Signs You Might Have the Dawn Phenomenon

• Elevated blood sugar in the morning (fasting glucose)

• Normal or low glucose before going to bed

• Feeling tired, thirsty, or mentally foggy upon waking

• Dry mouth or a headache in the morning

If your blood sugar jumps before breakfast even after a light or carb-free dinner, the dawn phenomenon may be the cause.

How to Confirm It’s the Dawn Phenomenon

Check your blood sugar at these times:

• Before bedtime

• Around 3 a.m.

• As soon as you wake up

If you notice a rise between 3 a.m. and morning, it’s a strong indicator.

Tips for Reducing Morning Blood Sugar Spikes

• Adjust your evening meal: Skip heavy carbs late at night; choose a balanced dinner with protein, fiber, and healthy fats.

• Try a late-night snack: A small protein-rich option, like Greek yogurt or a boiled egg, can help maintain stable blood sugar overnight.

• Stay active: Daily exercise improves insulin sensitivity; a post-dinner walk can be especially helpful.

• Review medications with your doctor: Adjusting dosage or timing may make a difference.

• Prioritize sleep: Poor rest raises cortisol, making morning glucose harder to manage.

• Limit late-night screen time: Blue light disrupts melatonin and circadian hormone balance, affecting glucose control.

When to See a Doctor

If morning spikes become common, don’t ignore them. Persistently high fasting blood sugar can increase the risk of heart disease, nerve damage, and vision problems. Your healthcare provider can help fine-tune your management plan or run further tests.

Final Thoughts

The dawn phenomenon is a natural process, but for those managing diabetes, it can be an unwelcome hurdle. The upside? With a few targeted lifestyle changes and proper guidance, you can minimize its effects and begin your mornings on a healthier note.