Is Falling Asleep After Eating a Sign of Diabetes?

Feeling sluggish after a hearty meal is a common experience for many, but could it signal more than just a full stomach? Diabetes, a condition where the body struggles to regulate blood sugar levels, poses this question. In diabetes, either the pancreas fails to produce enough insulin (type 1) or the body's cells become resistant to insulin's effects (type 2). Insulin is crucial for ushering glucose into cells for energy, so when its function is compromised, blood sugar levels soar, potentially damaging organs like the heart and nerves.

Given the link between blood sugar and fatigue, individuals with diabetes must carefully monitor their dietary choices. So, could post-meal drowsiness serve as a potential marker for diabetes?

Is falling asleep after eating a sign of diabetes?

The short answer is yes, possibly. Fatigue is common and affects up to 61% of people newly diagnosed with type 2 diabetes. However, there are other reasons that have nothing to do with diabetes.

Postprandial somnolence — the feeling of being sleepy after eating — is a familiar experience for many. It was long thought that the diversion of blood flow away from the brain toward the gastrointestinal tract during digestion led to sleepiness. Another theory has challenged this one, stating that sleepiness is due to the activation of sleep centers in the brain by hormones released during feeding.

Regardless of which theory is correct, it is normal even in healthy people to experience some degree of sleepiness after eating, although this is typically mild and should not disrupt daily life.

Experiencing sleepiness consistently after eating, however, may be a sign that your blood sugar levels are either outside of the normal range or fluctuating too rapidly. Both of these can be seen in people who have diabetes.

There is evidence that hyperglycemia (high blood sugar) leads to feelings of tiredness. In a study of 361 patients with diabetes, participants ranked tiredness fifth out of 16 of the most commonly reported diabetes symptoms. Additionally, 85% of the participants estimated that their symptoms, including tiredness, occurred when their blood sugar level was high (averaging 274 mg/dL), which, in people with diabetes, occurs most often after meals.

Why people with diabetes fall asleep after eating

When people with diabetes do not receive optimal treatment, the rise in blood sugar that occurs after meals can lead to greater postprandial somnolence compared to a person without diabetes. There are several explanations for why this may occur.

• First, hyperglycemia after meals can reflect the fact that insulin is not effectively bringing glucose into cells to use as energy. Therefore, people with uncontrolled diabetes must rely on another source of energy — fat — to meet their energy needs. One theory is that the body’s reliance on using energy in this way via ketosis may lead to fatigue in people with diabetes.
• Second, in people with diabetes, blood sugar levels may fluctuate more drastically. In other words, higher blood sugar rises are followed by sharp falls. These post-meal spikes and drops in blood sugar can make sleepiness worse among people with diabetes compared to healthy people, who do not experience as severe blood sugar fluctuations.
• Third, research shows that hyperglycemic episodes after meals may induce oxidative stress and inflammation leading to vascular complications in patients with diabetes. At the same time, people who have chronic fatigue syndrome have increased markers of oxidative stress. While these are merely correlations and do not imply that hyperglycemia causes fatigue, they suggest that a potential link exists between blood sugar control and fatigue.
• Finally, high blood sugar levels can also result in a process called osmotic diuresis. This can lead to increased urination and dehydration, which can potentially further contribute to fatigue after eating.

The opposite of hyperglycemia, hypoglycemia (low blood sugar) can also lead to tiredness after eating in people with diabetes. This usually occurs when a person consumes less food than usual after taking their regular dose of diabetes medication (particularly insulin). Too high levels of medication and not enough food can cause blood sugar levels to drop too low, which can cause tiredness along with other symptoms such as confusion and dizziness.

The best way to prevent postprandial somnolence due to hypoglycemia is to consume regular, balanced meals while on diabetes medications.

How to know if sleepiness is linked to diabetes

Because people without diabetes can also experience postprandial somnolence, it is challenging to tell whether sleepiness after meals alone is due to diabetes.

The best way to know whether post-meal sleepiness may indicate diabetes is by the presence of other symptoms of hyperglycemia that have to be diagnosed by a doctor. These include:

• Excessive thirst or urination
• Feeling hungry even after eating
• Unexplained weight loss
• Tingling or numbness
• Vision changes
• Wounds that heal slowly
• Recurrent infections

Additionally, if you routinely experience large ‘crashes’ in energy following meals or if your postprandial somnolence does not improve with changes to your diet, this may indicate poor blood sugar control and a greater likelihood of having diabetes.

Other reasons for being sleepy after eating

Although diabetes is a legitimate explanation for certain cases of postprandial somnolence, there are more common reasons you may want to take a snooze after eating. These include:

• Eating too much. Research has shown that overeating increases sleepiness and lethargy in the four hours after eating compared to eating only until comfortably full.
• Eating too many carbohydrates, fats, or proteins. While it is commonly believed that high carb consumption is responsible for postprandial somnolence, research has shown that eating too many fats or proteins can have the same effect. In fact, a study showed that a high-fat, low-carb meal was more likely to lead to sleepiness compared to a low-fat, high-carb meal. Nonetheless, some experts believe that high-carb meals cause postprandial somnolence by increasing the levels of serotonin — a hormone linked to sleep — in the brain.
• Eating too many simple sugars. Simple sugars such as those found in processed sweets and sugary drinks lead to a rapid spike in blood sugar levels followed by a fast decline in response to insulin, which some people refer to as a ‘sugar crash.’ A study of Chinese truck drivers found that those who consumed a diet high in desserts and sugary drinks had greater fatigue and made more driving mistakes compared to those who consumed vegetable-rich diets. To satisfy your sweet tooth, opt for diabetes-friendly desserts.

Additionally, natural circadian rhythms promote a dip in energy in the early afternoons even among healthy people. This explains why lunch is the meal that people most frequently associate with sleepiness; it coincides with the normal afternoon slump.

How can I prevent sleepiness after eating?

Postprandial somnolence may come and go over time depending on your dietary habits. The following are some strategies for potentially preventing tiredness after eating:

• Consume smaller, well-balanced meals. Eat until you are no longer hungry, not until you are overly full. Consume healthy meals and snacks containing a good mix of complex carbohydrates such as starchy vegetables, lean meats and fish, and healthy fats. One study showed that a ‘prudent’ diet consisting of a mix of root vegetables, milk and dairy, eggs, and vegetable oils led to less sleepiness.
• Avoid eating fried and sugary foods. Simple sugars and high fats found in processed snacks and fast foods may contribute to postprandial somnolence.
• Walk outdoors after eating. Research shows that brisk outdoor walking significantly reduces fatigue and improves working motivation and attention. Greater outdoor light exposure during the day may also lead to less tiredness and better sleep.
• Get good sleep. There are many ways to improve your sleep. Good sleep has been linked to better blood sugar control among people with diabetes.

Feeling sleepy after eating is a common experience even in healthy individuals. However, it is important to distinguish normal tiredness — particularly in the early afternoons following lunch — from the sleepiness and fatigue seen in diabetes. If you experience persistent post-meal sleepiness along with other symptoms such as excessive thirst, unexplained weight loss, or sensory changes, see your doctor to make sure that uncontrolled hyperglycemia is not at the root of the issue.