Your body is an incredible machine. When it’s operating how it’s supposed to, it vibes to its own rhythm, producing specific hormones, enzymes, and other substances when it needs them and reducing production when it doesn’t.
Sugar is one substance your body is always working with (or against, in some cases). The human body requires sugar to power countless reactions and functions, and the level of sugar in your blood will ebb and flow to meet those needs.
If you’ve been tracking your blood sugar levels either to manage pre-diabetes or to make progress in your weight loss journey, you may have noticed that your blood sugar levels experience fluctuations and are lower or higher around bedtime. This may spark some concern and bring up several questions about why this occurs and what impacts this may have on your sleep quality.
Why Are Blood Sugar Levels Different Around Bedtime?
A lot goes on in your body while you’re sleeping. Aside from dreaming, memory formation, muscle repair, and other functions, your body actively manages glucose during your slumber.
In a healthy human, it’s normal for blood sugar to fall a couple of hours after their last meal and remain on the low end of healthy fasted blood sugar until early morning. Your body doesn’t require as much energy to perform basic functions at night; thus, it doesn’t require as much circulating glucose or as much of the hormone insulin.
What Are Normal Glucose Levels Before Bedtime?
While it is normal for your blood sugar to decrease while sleeping, going to bed with high glucose levels can lead to restlessness and poor-quality REM sleep. Aiming for optimal glucose levels during the evening and nighttime can set you up for success and increase performance, concentration, and energy the following day.
What Should Blood Sugar Be At Bedtime for Non-Diabetics?
For non-diabetics, aiming for blood sugar levels around 70 to 100 mg/dL before going to sleep is optimal. This will allow you to wake up at 70 to 90 mg/dL, an ideal range for fasting glucose levels.
What Should Blood Sugar Be At Bedtime for Diabetics?
For people living with diabetes, measuring blood sugar levels before bedtime through a continuous glucose monitor (CGM) or other methods is critical to prevent hyperglycemia while sleeping.
According to the American Diabetes Association (ADA), the optimal glucose range for those living with diabetes is between 100 and 180 mg/dL, and should be no higher than 180 mg/dL two hours after a meal. If your blood sugar levels are below 100 mg/dL, this could also lead to dangerous health conditions.
Always consult a healthcare professional to determine your optimal blood sugar levels before bedtime and brainstorm strategies to ensure you hit this target.
What Causes High Blood Sugar Levels At Bedtime?
People living with diabetes may have some of these symptoms when their blood sugar is high:6
- increased thirst
- frequent urination
- blurred vision
However, if you don’t have diabetes, you likely will not experience symptoms related to high blood glucose levels. Why? Because your body manages glucose appropriately. You won’t have the same symptoms as a person living with diabetes who struggles to manage the excess glucose.
Numerous factors can contribute to glucose spikes and experiencing an elevated blood sugar level before bedtime, including the below activities.
Late Evening Meals and Snacks
Eating too late could disrupt a good night's sleep by interfering with your natural circadian rhythms that control metabolism.¹ What does that mean exactly? Your circadian rhythm is an internal clock that controls when you feel awake, alert, or sleepy. It also regulates hormones like insulin (which is at its lowest levels overnight), so you are more efficient at using and digesting nutrients earlier in the day.²
Steroids, such as hydrocortisone, dexamethasone, and prednisone, are often used to control inflammation, manage asthma flare-ups, or suppress autoimmune reactions. However, these medications also can cause a dramatic increase in blood sugar.
Even people without diabetes may experience steep spikes in blood sugar while taking steroids, and long-term treatment may increase a person’s chance of developing diabetes.7
However, inhaled steroids for asthma and topical formulations such as creams and ointments won’t affect your blood sugar.
Some medications used for depression, anxiety, ADHD, birth control, high cholesterol, or high blood pressure also can increase blood glucose levels.
Alcoholic beverages contain carbohydrates and are often high in calories, which can wreak havoc on your blood sugar control. Alcohol also stimulates your appetite, which can prompt you to eat more, making it more difficult to stay within the ideal glucose range.8
What’s more, the body prioritizes alcohol metabolism first, so any food you might eat with that glass of wine, beer, or spirit gets processed after the alcohol. This can lead to more prolonged or delayed glucose responses to the food you eat while drinking.
Believe it or not, stress can be a huge factor that affects your blood sugar. During emotional hardship, your body releases stress hormones, such as cortisol, which prompts an increase in glucose even if you haven’t eaten.
Much like emotional stress, sickness can impose physical stress on your body. Whether it’s a cold, the flu, or something more serious, your body responds to illness by releasing glucose.9 When you’re sick, you may be surprised to have high blood sugar even if you haven’t had normal food intake.
Sugary Drinks Before Bed
It may be obvious that sweet drinks like soda and juice will spike your blood sugar, but consuming sugary beverages can be a hard habit to break. Many people opt for artificially sweetened beverages in place of the real deal.
However, a review of current research suggests that artificially-sweetened drinks may affect glycemic control (albeit indirectly).10 Artificial sweeteners may also alter your gut microbiota; one study examined in the review demonstrated that artificial sweeteners induce glucose intolerance in mice and human subsets. More research is needed to fully understand the role of artificial sweeteners in managing blood sugar.
Good old-fashioned water is always the best choice for hydration and health.
With less water in your bloodstream, glucose becomes more concentrated. Drinking adequate amounts of water is crucial for optimal blood sugar control.
Hormonal changes that occur in the premenstrual phase of a woman’s monthly cycle may play a role in raising blood sugar levels.11 More research is needed to understand this phenomenon fully.
Poor Sleep Hygiene
It is well-documented that poor sleep has wide-ranging effects on how our bodies process glucose. Sleep problems are linked not only to high blood sugar but also insulin resistance, type 1 diabetes, type 2 diabetes, metabolic syndrome, and obesity.12
How To Prevent High Blood Sugar Levels At Bedtime
If you’re using the Signos app, you’ll receive an alert to let you know when your glucose is out of range. If your glucose is high, consider engaging in one of the below activities. Once you use the SIgnos app for a consistent amount of time, you will start to recognize patterns around your spike. Consider incorporating one of the following ideas into your routine to mitigate and decrease your spike activity throughout the day.
Avoid eating at least 3 hours before bedtime
Eating before bed may increase weight gain and other markers of metabolic health like insulin, fasting glucose, cholesterol, and triglycerides.³ Sleep is also a time of repair. During overnight fasting, your body can complete critical processes it can't do during the day, like cellular repair. Eating late at night could affect this by stimulating digestion and taking away energy that would otherwise be used for restorative processes.
Minimize carb intake at dinner
Meals full of both fat and carbohydrates may require a longer time for digestion, resulting in higher glucose readings several hours after eating.
One study with young, healthy participants showed that eating a late dinner composed of 50% carbs, 35% fat, and 35% of total daily calories caused prolonged glucose intolerance and reduced fatty acid oxidation during sleep—particularly in those who hit the hay earlier—and an increase in cortisol.4 Researchers hypothesized that these same metabolic reactions could contribute to obesity if repeated consistently.
Get some movement after dinner
After eating a meal, your body begins breaking down food for digestion, and carbohydrates specifically are broken down into glucose (i.e., blood sugar). At this point, your pancreas releases insulin to help your body absorb the sugars out of your bloodstream, where it is then stored in the liver as glycogen or used immediately for energy. For those who are insulin resistant (i.e., those living with type 2 diabetes), your body does not receive a very strong signal from the insulin that is released. This maintains the high levels of sugar in your blood and causes the blood sugar spikes you may see after eating. Increasing your sensitivity to insulin through changes in diet and exercise helps your body to better receive messages from insulin and quickly absorb the sugars from your blood, thus reducing circulating blood sugar levels before noticing a spike.
Walking has been shown to improve insulin sensitivity and lower blood sugar because our working muscles require the sugar in our blood to function. This is why walking after eating a meal - instead of before - has been shown to help reduce spikes in blood sugar and help with long-term blood sugar control.5
Keep yourself hydrated
Two of the symptoms of high blood sugar are increased thirst and dryness of the mouth. This is the body’s counteractive mechanism urging you to drink water to clear out excess glucose and recalibrate blood glucose concentrations.
So, by increasing your water consumption, you’ll feel the need to urinate frequently. This can excrete excess sugars from your blood and decrease your glucose levels.
Take time to unwind
Believe it or not, stress can be a huge factor that affects your blood sugar. During emotional hardship, your body releases stress hormones, such as cortisol, which prompts an increase in glucose even if you haven’t eaten. While you can't plan to block sudden bouts of stress, you can prevent and manage chronic stress. The following strategies can help:
- Spending time with loved ones
- Spending time in nature
What Happens If You Go To Sleep With High Blood Sugar Levels?
Rises and dips in blood sugar levels are completely normal and not a normal cause for concerns. However, high blood sugar levels before bed can cause several symptoms including:
- Increased cortisol levels
- Reduced insulin sensitivity
- Increased oxidative stress, and inflammation
Frequent high blood sugar levels before bed could also cause hyperglycemia, which is a normal process in response to some foods or stress. However, sustained hyperglycemia over a consistent period is a symptom of diabetes. It can lead to the following complications:
- Diabetic retinopathy: abnormal blood vessels on the retina that can cause vision impairment
- Nephropathy: impaired kidney function
- Neuropathy: nerve damage
- Coronary artery disease: plaque buildup in your arteries that could eventually lead to a heart attack or heart disease
- Cerebrovascular disease: impairs blood flow to the brain, which could lead to stroke
- Diabetic ketoacidosis (DKA): a medical emergency that requires immediate attention and could lead to organ damage, brain swelling, muscle weakness, and heart failure.
Does Blood Sugar Change While Sleeping?
The Dawn Phenomenon
Around 2 to 8 am, depending on your sleep cycle, blood sugar begins to rise as part of your body’s preparation for the day.13 Some doctors and scientists believe this happens because your body releases hormones affecting your blood sugar.
In the early morning hours, your body produces more of the hormone glucagon, which stimulates blood sugar circulation, and cortisol, which counteracts the effects of insulin. Increases in epinephrine and growth hormone also affect insulin production.
During this early-morning surge of sugar and hormones, your body should also start releasing insulin, which should be hard at work, notifying muscle, fat, and liver cells to start taking up sugar in the blood. If you’re healthy, your blood sugar won’t remain high for long, and you won’t experience any complications from the temporary rise in blood sugar.
The Somogyi Effect
In people living with diabetes, early morning blood sugar levels may read very high due to insulin resistance or lack of insulin production. This is called the Somogyi effect and, if persistent, can lead to a high A1C and related health complications.14
The Somogyi effect is thought to be a rebound reaction to low blood sugar and is the body’s attempt at “rescuing” you from low blood sugar while you sleep.
General Tips to Stabilize Blood Sugar Levels Before Bed
If your blood sugar is below your target range at bedtime, try eating a small, healthy snack to return to your target blood sugar range such as
- One serving of a medium or low glycemic fruit. Consider options such as apples, strawberries, oranges, bananas, pears, or dates. Avoid watermelon, pineapple, and other high-glycemic fruits, or choose a smaller serving.
- several whole-grain crackers
- a cup of milk
- plain Greek yogurt
- a hardboiled egg
- a handful of nuts
- veggies with hummus
If your blood sugar is still bouncing all over the place at night and not within the range of your blood sugar goals, try these simple changes to your evening routine.
- Don’t skip dinner.
- Eat a balanced evening meal with plenty of veggies and lean protein.
- Eat dinner at least three hours before bedtime.
- Take your blood sugar level before bed.
- Eat a healthy snack if your sugar is low at night.
- Give yourself 10 minutes of exercise if your sugar is high before bed.
- If you experience low blood sugar overnight, don’t engage in intense exercise right before bed.
- Be sure to get at least 7 hours of sleep each night.
- Minimize stress.
- Practice meditation before bedtime.
- Drink plenty of water throughout the day.
- Be sure to engage in a regular schedule of exercise.
- Avoid drinking alcohol at night.
As you implement these tips for managing your glucose, remember that it’s a process. Continuous glucose monitoring will allow you to get to know your body better with time, and you’ll begin to understand exactly what your body needs.
And remember—strive for progress, not perfection.
Get more information about weight loss, glucose monitors, and living a healthier life
Topics discussed in this article:
- Marcheva, B., Ramsey, K. M., Peek, C. B., Affinati, A., Maury, E., & Bass, J. (2013). Circadian clocks and metabolism. Handbook of experimental pharmacology, (217), 127–155. https://doi.org/10.1007/978-3-642-25950-0_6
- Stenvers, D. J., Scheer, F. A. J. L., Schrauwen, P., la Fleur, S. E., & Kalsbeek, A. (2019). Circadian clocks and insulin resistance. Nature reviews. Endocrinology, 15(2), 75–89. https://doi.org/10.1038/s41574-018-0122-1
- Lopez-Minguez, J., Gómez-Abellán, P., & Garaulet, M. (2019). Timing of Breakfast, Lunch, and Dinner. Effects on Obesity and Metabolic Risk. Nutrients, 11(11), 2624. https://doi.org/10.3390/nu11112624
- Aqeel, M., Forster, A., Richards, E. A., Hennessy, E., McGowan, B., Bhadra, A., Guo, J., Gelfand, S., Delp, E., & Eicher-Miller, H. A. (2020). The Effect of Timing of Exercise and Eating on Postprandial Response in Adults: A Systematic Review. Nutrients, 12(1), 221. https://doi.org/10.3390/nu12010221