More than 130 million Americans are living with diabetes or prediabetes, according to the Centers for Disease Control and Prevention (CDC). If you've been managing your diabetes well, it may feel frustrating to wake up to elevated blood sugar numbers in the morning. But this could be due to a natural phenomenon called the "dawn effect."
Here, learn about what causes the dawn effect, why it happens and tips for overcoming it, according to diabetes experts.
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What Is the Dawn Effect?
The dawn effect, also known as the dawn phenomenon, refers to recurring high blood sugar levels between the hours of 3 a.m. to 8 a.m., per the National Library of Medicine.
"This effect is very common, and the physiological processes that underlie the dawn phenomenon can occur in everyone — whether they have diabetes or not," says Jeff Stanley, MD, diabetes doctor and spokesman for Virta Health.
People who don't experience the dawn effect are able to release enough insulin to counteract the increase in blood sugar levels, Dr. Stanley says.
Why Does the Dawn Effect Happen?
Hormones play a big part in the dawn effect. Certain hormones naturally increase in the early morning hours. Doctors think this happens to give us a necessary and natural boost of energy, per Johns Hopkins Medicine.
When you wake up, adrenaline, cortisol, glucagon and growth hormone are released into your bloodstream. This leads to the release of glucose, or blood sugar, Dr. Stanley says.
"Two key processes occur in the liver overnight that cause a release of glucose into the bloodstream and contribute to increased blood sugar in the morning," he adds. These processes include:
- Glycogenolysis: When stored glucose breaks down and is released for energy
- Gluconeogenesis: When the protein and fat in our bodies is used to make glucose for energy
Insulin also plays a role here, of course. When glucose levels rise, insulin is released soon after. Insulin helps sugar enter your cells, where it can be used for energy or stored as fat, per the CDC. All of these factors play into the high blood sugar levels you experience with the dawn effect.
How Does It Affect People With Diabetes?
Everyone — whether you have diabetes or not — reacts differently to the dawn effect. While some people don't notice any symptoms, others may feel the effects of a blood sugar spike. The side effects of high blood sugar can include, per the CDC:
- Intense hunger or thirst
- Mood swings
A person without diabetes typically gets enough insulin from their pancreas to counteract this spike. But when you have diabetes or prediabetes, your pancreas doesn't make enough insulin, or your cells aren't as sensitive to it anymore, per the Cleveland Clinic. In that case, you are more likely to feel those high blood sugar symptoms.
7 Tips for Overcoming the Dawn Effect if You Have Diabetes
Dr. Stanley suggests the following steps to ensure healthy blood sugar numbers:
1. Check Your Blood Sugar Often
Check your blood sugar before bed, in the middle of the night and first thing in the morning.
"Understanding when your blood sugar is spiking is the first step to understanding what might be causing these spikes, and determining the best way to counteract the dawn effect," Dr. Stanley says.
2. Identify Your Triggers
If your blood sugar is high at night, it could be because you are eating too late. Or it could be due to your diabetes medication. If you have high blood sugar in the morning, it's possible your medication dose is too low.
Of course, talk with your doctor to see if adjusting your medication dosage is right for you.
3. Change the Timing of Your Insulin Injection
If you take insulin for your diabetes, talking with your doctor about changing the time of night you inject yourself may be helpful, per the Mayo Clinic.
4. Consider an Insulin Pump
If you're having a difficult time keeping track of your insulin dosage or the timing of your injections, your doctor may recommend an insulin pump. These are small devices that continuously deliver insulin through a small plastic tube, and they can deliver it quicker than injections, per the National Library of Medicine. This may help ease the elevated blood sugar numbers associated with the dawn effect.
5. Try Evening Exercise
Exercising in the afternoon or evening, especially after meals, may have a positive effect on your blood sugar levels the next morning. "Taking a walk after dinner may help lower your blood sugar," Dr. Stanley says.
In fact, a randomized February 2019 study in Diabetologia found that afternoon high-intensity workouts were more effective than morning high-intensity workouts at improving blood glucose levels in men with type 2 diabetes. However, more studies need to be done to determine the most ideal exercise timing for glucose control. (Note: The study authors identified their participants as men, which is why we've included this gendered language. LIVESTRONG.com otherwise tries to avoid using gendered language.)
6. Eat Foods That Will Regulate Blood Sugar
Plan meals ahead of time to ensure stable blood sugar levels during the day.
"Eating a low-carb, high-fat diet with lots of non-starchy vegetables, like spinach, kale and broccoli, can help normalize blood sugar throughout the day," Dr. Stanley says. "You can also eat dinner earlier in the evening and avoid high-carb snacks in the evening."
7. Try to Get 6 to 8 Hours of Sleep Each Night
Sleeping at least six hours may help reduce cortisol levels in your body, which has a positive effect on insulin levels. Indeed, a November 2015 study in Sleep Science found an increase in cortisol levels during periods of total sleep deprivation, both at night and during the day.
If your cortisol levels are too high, you can become insulin-resistant, meaning you'd have to take more insulin if you have diabetes, per the University of California San Francisco.
"Get a good night's sleep, at least six to eight hours each night, and go to bed before midnight," Dr. Stanley says. "This may help reduce cortisol and improve your ability to tolerate blood sugar spikes," he adds.
The Bottom Line
If the dawn effect is negatively affecting your blood sugar levels and you have diabetes, make sure you talk with your doctor before making any lifestyle or medication changes.
The CDC also encourages people with diabetes to educate themselves on the topic and look for support and resources in their area, like a diabetes education counselor or support group. Learning how to confidently manage diabetes, including the dawn effect, can delay or prevent further health complications.
- National Library of Medicine: "Dawn Phenomenon"
- Johns Hopkins Medicine: "Sleep/Wake Cycles"
- CDC: Diabetes Basics
- Virta Health: "Jeff Stanley MD"
- National Library of Medicine: "Insulin Pumps"
- Diabetologia: "Afternoon exercise is more efficacious than morning exercise at improving blood glucose levels in individuals with type 2 diabetes: a randomised crossover trial"
- Mayo Clinic: "The dawn phenomenon: What can you do?"
- Sleep Science: "Interactions between sleep, stress, and metabolism: From physiological to pathological conditions"
- UCSF: "Blood Sugar & Other Hormones"
- Cleveland Clinic: "Insulin Resistance"
- Diabetes Basics
- Dawn Phenomenon
- Insulin Pumps
Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.