What is the dawn phenomenon?

A surge of hormones

that the body produces daily in the early morning hours

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Disclaimer: This information isn’t a substitute for professional medical advice, diagnosis, or treatment. You should never rely upon this article for specific medical advice. If you have any questions or concerns, please talk to your doctor.

What is the dawn phenomenon?

The dawn phenomenon refers to a surge of hormones—including cortisol, glucagon and epinephrine—that the body produces daily in the early morning hours. This release leads to elevated level of blood glucose or blood sugar—the body’s go-to fuel source.

I think of the dawn phenomenon as an evolutionary solution for getting us up in the early morning and giving us the energy boost we need to go about and do our business. For most of human history it was hunt or be hunted, and this hormonal surge gave our ancestors a better chance of survival and passing on their genes. Ultimately, those genes were passed down to us.

While everyone experiences and indeed benefits from the dawn phenomenon, people with diabetes don’t have normal insulin responses to adjust for it. This can result in their fasting glucose shooting up, causing an array of unwanted effects which we’ll get to in a moment.

What causes dawn phenomenon? 

We can think of insulin as a key that unlocks the cell so that glucose can get in and be used for fuel.  The body produces less of this hormone during the evening hours, as we’re not moving around as much.

In the early morning however, other hormones that are tied to our circadian rhythm get to work on getting us the energy we need for the day ahead. They do this by telling glucose to get out of the liver and start circulating throughout the body. In people without diabetes, insulin levels rise along with this increase in glucose, enabling it to do its thing. In people with diabetes however, there’s either a lack of insulin or a resistance to insulin at the cellular level. This means that blood glucose can’t be used for energy and remains elevated in the blood.

What are the signs and symptoms of dawn phenomenon? 

This nighttime spike in glucose is called fasting hyperglycemia and it can bring on several symptoms. These can include extreme thirst, fatigue, nausea, vomiting, blurred vision, weakness, and disorientation.

While all of these symptoms are certainly unpleasant, the situation can get much worse is if blood sugar levels continue to rise as a result of the dawn phenomenon. In some cases, this can result in diabetic ketoacidosis and become a life-threatening medical emergency.

Diabetic ketoacidosis refers to a dangerous build up of acid in the bloodstream.  It can happen when energy in the form of glucose can’t be unlocked with insulin. In response, the body switches to another source of fuel—fat. Fat is much harder to get at than glucose. The process of breaking it down produces a buildup of acids in the bloodstream called ketones which, left untreated, can lead to diabetic ketoacidosis. This condition could end up with someone losing consciousness, experiencing a diabetic coma, and even be fatal.

People with type 1 diabetes or who frequently miss doses of insulin are far more likely to develop ketoacidosis though it can occur in people with type 2 as well. Often, it’s the first sign that someone has diabetes.

Dawn phenomenon vs somogyi effect

The dawn phenomenon and something called somogyi effect are often are often mistaken for one another, though their underlying causes are quite distinct and need to be addressed differently.

Unlike the dawn phenomenon, the somogyi effect is is it is not driven by a spurt of cortisol in the early morning hours but by an overnight drop in blood sugar. Anytime blood sugar drops below a certain threshold, the brain will tell the liver to go into overdrive. When prompted, the liver makes more sugar and releases it, ten breaks down more glycogen to make more sugar. As you can imagine, for anyone experiencing the somogyi effect, this can feel like a rollercoaster ride.

So the Somogyi effect is response to overnight hypoglycemia whereas the dawn phenomenon is really a phenomenon related to insulin resistance and increased blood glucose in response to cortisol and other hormones.

How can I treat dawn phenomenon? 

As mentioned above, early morning cortisol production is an innate part of human physiology and, in people without diabetes who have normal adrenal function, it’s not something that needs to be addressed.  In people with diabetes, there are things you can do to reduce its impact on your life.

One way to address the hyperglycemia conferred by the dawn phenomenon is to engage in physical activity shortly after waking. In fact, exercise can help with insulin resistance all day long. Another is to make better food choices. If you wake up with high blood sugar, eating foods with a high glycemic index is likely to make the symptoms worse. Toast, bagels, muffins, oatmeal, preserves are all things we associate with breakfast and all of them will raise blood sugar considerably. This makes it harder for the body to bring those levels back down.  The best foods to eat for breakfast are foods that contain protein and fiber. Greek yogurt, dairy, eggs,maybe a little bacon and sausage, are much better choices.

Beyond making lifestyle changes, some medications and devices can be effective at reducing the dawn phenomenon, especially an insulin pump as the pump’s settings can be changed to provide the patient with more basal insulin in the early morning hours.

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