Metabolic Health 7 MIN READ

What Do Blood Glucose Spikes At Night Mean And How To Prevent It

The Dawn Phenomenon usually occurs between 3 AM and 8 AM. As the body prepares to rise and greet the day, read more about preventing it.

Written by Team Ultrahuman

Jan 09, 2023
Blood Sugar Prevent

Ever been baffled by your glucose readings going berserk with glucose spikes first thing in the morning? Glucose is the fuel that the body runs on. But when glucose starts to build up in the bloodstream, it can lead to blood sugar levels quickly shooting through the roof. What makes glucose levels spike when you’re asleep at night? There are a few reasons. Let’s look at them more closely so we can understand why they happen and how to keep them in check.

Blood sugar night


  • The Somogyi Effect refers to blood sugar levels plummeting overnight. The body takes it as a cue to release the counter-regulatory hormones, glucagon, adrenaline and cortisol which raise blood sugar levels in order to keep them from falling too low,
  • The best way to tell what’s causing overnight high blood sugar levels is by checking your blood glucose level between 2 a.m and 3 a.m,
  • By managing diet, managing stress, getting adequate exercise and sleep and staying hydrated one can prevent blood glucose levels from shooting up at night.

If you’re prone to erratic snacking or work night shifts, high blood sugar at night often boils down to a late-night high-carb meal or snack. And if your meal was high in fat in addition to being carb-heavy, this can delay blood sugar absorption, causing glucose levels to rise several hours after eating. Alternatively, if you’re on diabetes medication, not taking the right dose at the right time can also throw blood sugar levels out of whack.

What do Blood Sugar spikes at night mean?

What is Dawn Phenomenon?

If your nocturnal sugar spikes have nothing to do with erratic meal times or diabetes medication, you just may have brushed up against the Dawn Phenomenon or the Somogyi Effect. The Dawn Phenomenon or Dawn Effect usually occurs between 3 AM and 8 AM. As the body prepares to rise up and greet the day, it sends a memo to the liver to pump more glucose into the blood so that there is enough fuel to run on.

This simultaneously triggers the release of insulin, the hormone in charge of blood sugar regulation, to keep sugar levels from going too high, which is why this usually goes unnoticed in non-diabetic people. In people with diabetes, however, the body either does not produce enough insulin or does not use insulin efficiently, leading to hyperglycemia or high blood sugar.

What is Somogyi Effect or Rebound Hyperglycemia?

The Somogyi Effect or rebound hyperglycemia refers to blood sugar levels plummeting overnight. When this happens, the body takes it as a cue to release the counter-regulatory hormones (insulin-antagonistic hormones that function against the action of insulin), glucagon, adrenaline, and cortisol to raise blood sugar levels in order to keep them from falling too low. Sometimes, there is an over-correction that actually leads to hyperglycemia or elevated blood glucose levels.

Diet induced spikes

What causes your Blood Glucose spikes at night?

If you suspect overnight high blood glucose levels, the best way to tell what’s causing it is by checking your blood glucose level between 2 a.m and 3 a.m. A low blood glucose level at this time is indicative of the Somogyi Effect, while a high reading suggests it’s the Dawn Phenomenon. Tracking your glucose levels before going to bed, between 2 AM and 3 AM and again, first thing in the morning, through continuous glucose monitoring (CGM) or a finger-prick test, can help you take the necessary steps in checking any blood glucose imbalance. 

How to prevent Blood Glucose spikes at night?

Here are 5 ways to control or prevent blood glucose spikes at night:

1. Managing diet 

Diet plays a major role in glucose fluctuations. Studies have shown that a low-carb, high-protein diet with a good amount of omega-3 fatty acids can go a long way in keeping postprandial glucose spikes at bay. Studies also demonstrate that the timing of meals can have an impact on blood glucose levels, which tend to be higher after evening meals when compared to morning meals. Eating closer to bedtime can cause sugar spikes at night. In the case of the Dawn Phenomenon, eating a lighter breakfast is recommended.

With the Somogyi Effect, time-restricted eating approaches which focus on when you eat rather than what you eat, and intermittent fasting, have also proven to be effective in managing morning blood glucose levels, keeping them in the normal range.

In the fasting state, the body uses energy stored in the body instead of sourcing it from the recent meal. Regularly tracking glucose levels, keeping an eye on foods that make them rise, and consulting a professional nutritionist are all good first steps in planning a diet that’s right for you. 

2. Managing stress and sleep 

Stress is often dismissed as an emotional problem, having nothing to do with physiology. But what goes on in the body when we’re under stress and sleep-deprived, has a direct impact on our blood glucose levels. First, the adrenal glands release norepinephrine or adrenaline which converts glycogen into glucose, elevating blood sugar levels.

If the stress continues, the body also releases cortisol, (after the epinephrine surge subsides), the stress hormone associated with the ‘fight or flight mode.’ It further increases blood sugar levels to provide immediate energy for fighting or fleeing the situation.

This is also the case when we cannot get adequate sleep and still have to push through a day of work. While cortisol rushes to rescue us from these tight spots and keeps us functional, it also reduces the body’s insulin sensitivity, leading to spikes in blood sugar levels. Meditation, relaxation techniques and a good night’s rest—about 7-9 hours of high-quality sleep—can play a significant role in managing glucose levels at night.

3. Getting the right amount of exercise 

Exercise can have a positive impact on blood glucose levels but moderation is key because there is such a thing as the right amount and the right kind of exercise. While glucose levels tend to rise with too little exercise, they are at equal risk of shooting up when you over-exercise. Moderate or low-intensity exercise is best recommended to lower glucose levels at night. Studies show that a twenty-minute low-intensity treadmill workout after dinner can reduce postprandial blood sugar levels in people with type 2 diabetes. Exercising earlier in the evening can also help stabilise blood glucose levels in the morning.

pexels yuliya mulyukina 10740332 min

4. Staying hydrated 

Staying hydrated is crucial when it comes to blood glucose control. When you’re dehydrated, the body releases a hormone called vasopressin which causes the liver to release more sugar into the bloodstream and instructs the kidneys to retain water, which prevents excess sugar from getting flushed out. Needless to say, elevated vasopressin levels in the body are not good news for blood sugar control. According to a study published in Diabetes Care, those who reported a low water intake of less than 1 litre a day were at a higher risk for high blood sugar.

5. Maintaining oral hygiene

According to recent studies, gingivitis or gum disease can also lead to blood glucose levels skyrocketing when you’re asleep. After brushing or chewing, some of the germs in the infected gums leak into the bloodstream, triggering the body’s defence system. In turn, this releases powerful molecules that have harmful effects all over the body, one of which is raising blood glucose levels. Maintaining proper oral hygiene is therefore closely linked with blood sugar control.


High glucose levels at night or glucose spikes at night happen for a variety of reasons. While a late-night carb-heavy meal is often the main accused, it also happens as a result of the Dawn Phenomenon and the Somogyi Effect. In the Dawn Phenomenon, hyperglycemia is the result of the body preparing to wake up and greet the day, whereas, in the Somogyi Effect, high blood sugar is a result of the counter-regulatory hormones glucagon, adrenaline, and cortisol, attempting to correct a sharp fall in blood sugar levels by elevating them at night. Additionally, diabetes medication taken in the wrong dosage can also lead to high blood sugar at night. Checking glucose levels between 2 AM and 3 AM is the best way to distinguish between hyperglycemia induced by the Dawn Phenomenon and the Somogyi Effect. Some measures that can be taken to prevent blood glucose levels from shooting up at night include managing diet, managing stress and getting adequate sleep, getting the right amount of exercise, staying hydrated, and maintaining oral hygiene.

Disclaimer: The contents of this article are for general information and educational purposes only. It neither provides any medical advice nor intends to substitute professional medical opinion on the treatment, diagnosis, prevention or alleviation of any disease, disorder or disability. Always consult with your doctor or qualified healthcare professional about your health condition and/or concerns and before undertaking a new health care regimen including making any dietary or lifestyle changes.


  1. Somogyi Effect and Dawn Phenomenon
  2. Effects of Meal Timing on Postprandial Glucose Metabolism and Blood Metabolites in Healthy Adults
  3. Blood Sugar: Hidden Causes of High Blood Sugar Levels in the Morning
  4. Moderate-Intensity Post-Dinner Exercise Reduces the Postprandial Glucose Response
  5. Low Water Intake and Risk for New-Onset Hyperglycemia

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