Written by Lauren Ranley, MS, RD, LDN
Sleep is vital for overall health and wellbeing, but even more so for diabetes management. One study investigated the link between sleep disruptions and type 2 diabetes. The study showed that people with diabetes often have poor sleep habits, including difficulty falling or staying asleep. While the mechanism for such impaired sleep is not entirely understood, the relationship is evident. Poor sleep can also affect glucose levels in non-diabetic individuals. A compelling sleep study selected people with no signs of diabetes or blood sugar issues and limited their sleep to four hours a night for six nights. By the end of the week, the participants were given an IV Glucose Tolerance Test and appeared to have clinical prediabetes glucose levels. Sleep deprivation is a preventable contributor to poor blood sugar levels.
What Happens to Your Blood Sugar While You Sleep?
Throughout the day, blood sugar levels rise after you eat, reaching their highest point about 30 minutes post-meal, then drop within two hours after eating.
While we sleep, the body uses a cycle of hormones, including insulin, cortisol, glucagon, and growth hormone, to stabilize blood sugar levels.
When blood sugar levels are high, the pancreas releases insulin, which allows glucose to funnel out of the bloodstream and into cells. On the other hand, when blood sugar levels are low, counterregulatory hormones, like cortisol and growth hormone, signal the liver to release glucose into the blood.
These counterregulatory hormones and insulin create a balance to maintain normoglycemia, or normal blood sugar levels. Disruptions in this balance are closely linked to the quality and quantity of sleep.
Here is an example of the cycle of hormones during sleep and how blood sugar levels are affected:
8 pm - 10 pm: The body prepares for sleep. After dinner, blood sugar will temporarily rise and fall around bedtime. Aim to be in bed by 10 pm.
11 pm: If you have not yet gone to sleep, low blood sugar levels may cause a cortisol spike, signaling the liver to release glucose, giving you a second wind and keeping you awake longer.
12 am - 4 am: Cortisol levels should be at their lowest. If you tend to wake up during this period, it may be due to occasionally low blood sugar. Try having a snack with protein and healthy fats before bed.
8 am: Cortisol levels reach their highest as the body prepares to wake, and normal blood glucose levels should be between 70-100 mg/dL.
Recurring disruptions in sleep can have detrimental effects on carbohydrate digestion and cause cells to be less receptive to insulin. Keeping a consistent sleep schedule plays a key role in blood sugar management.
The Dawn Phenomenon
People with diabetes may see a morning blood sugar spike due to changes in the normal hormone cycle during sleep. In a normal hormone cycle, the body releases counterregulatory hormones, mentioned earlier, around 3 - 8 am to prepare the body for waking. However, the Dawn Phenomenon occurs when insulin resistance prevents the body from adequately balancing the increase in blood sugar. Individuals with diabetes can experience high blood sugar readings in the morning, even with normal blood sugar levels the night before.
Dawn Phenomenon Treatment
Check your blood sugar level an hour before bedtime. To avoid low blood sugar levels while sleeping, experiment with bedtime snacks that will keep you in range overnight, like hummus or guacamole with vegetables, a protein smoothie, or a glass of almond milk and a banana. If you experience high blood sugar levels in the morning, a health care provider may recommend a 3:00 am blood sugar check to determine the cause. Using a continuous glucose meter allows you to check your levels without waking up.
The Somogyi Effect
High morning blood sugar can also be attributed to your body overcompensating for lower blood sugar overnight. The Somogyi Effect typically occurs in individuals who take insulin or other blood sugar-lowering medications at night. The medications cause a drop in blood sugar, and your body rebounds by releasing a surge of glucose. Like the Dawn Phenomenon, insulin resistance doesn’t allow the body to bring blood sugar levels back into a normal range. Signals that you are experiencing low blood sugar overnight include waking up in the middle of the night with headaches and excessive sweating or having difficulty waking up in the morning.
Common Questions About Sleep and Type 2 Diabetes
What should blood sugar be at bedtime?
Ideally, blood sugar should be in the standard range of 70-100 mg/dL (3.9 and 5.5 mmol/L) or <140 mg/dL (7.8 mmol/L) if taken within two hours after a meal.
Is it safe to sleep with high blood sugar?
Just as sleep can affect blood sugar regulation, high blood sugar can affect the quality of sleep. While elevated blood sugar levels at night don’t pose an immediate concern, they can cause poor sleep.
Does high blood sugar make you sleepy?
Cells of the body use glucose for energy. With insulin resistance, glucose cannot enter the cells and provide that energy, causing high blood sugar levels. Fatigue experienced when blood sugar levels are high is due to the cells’ lack of energy.
Does Metformin keep you awake at night?
Like other medications, Metformin may have side effects, some people may experience insomnia and sleep disturbance.
What is the best sleep position for people with diabetes?
While there is no one optimal position to sleep in, to ensure a good night's rest, make yourself comfortable and relaxed when going to bed. For more tips, see our list of “8 helpful tips for getting a good night’s sleep” below.
I’m diabetic and sleeping too much. How come?
As mentioned earlier, the inability of glucose to enter cells and provide vital energy can lead to fatigue. Elevated blood sugar also impacts quality of sleep which can lead to increased fatigue as well.
8 Helpful Tips for Getting a Good Night's Sleep
- Relax before bedtime. Finish activities like exercise, chores, errands, etc., an hour before bed.
- Go to bed at the same time every day, even on the weekends, if you can. Try not to take a nap late in the day.
- Don’t eat a heavy meal right before bedtime, and avoid drinking alcohol or caffeine late at night.
- Limit all fluids at least an hour before bedtime to avoid waking up in the middle of the night to go to the bathroom. Use the bathroom right before you go to bed, too.
- If you’re stressed, try relaxation techniques like meditating, deep breathing, yoga, reading a favorite book, listening to calm music, or writing in a journal.
- Make your room comfortable: not too cold or hot, quiet, and dark. If you currently use your bedroom as an office or another TV room, rethink this arrangement. Make your bedroom a place to rest, not get distracted.
- Put all electronics away before bedtime, especially mobile devices like your smartphone or tablet.
- We know you love your pets, but they can interrupt your sleep, so try to keep them off the bed or out of your room altogether, especially if you have allergies (diabetes-alert dogs excluded, of course).
 Van Cauter E, Spiegel K, Tasali E, Leproult R. Metabolic consequences of sleep and sleep loss. Sleep Med. 2008 Sep;9 Suppl 1(0 1):S23-8. doi: 10.1016/S1389-9457(08)70013-3. PMID: 18929315; PMCID: PMC4444051.