Sleepy After Eating? Why Does it Happen & Ways to Prevent It

When we eat out meals, we expect ourselves to be energized or rejuvenated. However, often feeling tiredness or drowsiness takes over us after we have finished eating.  Known as postprandial somnolence, this decrease in energy levels after meals can be a natural result of digestion or sleep cycles.

A bit of sleepiness after meals is quite common and natural and is nothing to worry about. However, in some rare cases, lethargy may be a symptom of a medical condition. Scientists have put forward various theories about the causes of post-meal tiredness. Learn about these theories and ways to minimize drowsiness after meals.


Likely causes of tiredness

1. Digestion

Our body needs the energy to function, and it obtains this energy from the food we eat.  When we eat food, our body breaks down the nutrients from the food into glucose that is then converted into energy. Our body also releases hormones like amylin, glucagon, and cholecystokinin during the digestive process. These hormones increase blood sugar levels, create a feeling of fullness, and produce insulin. During the same time, the brain releases serotonin that causes drowsiness.  Food also influences the production of melatonin in the brain.

2. Diet

The kind of food that you eat can also make you tired after meals.


Foods that are rich in proteins like meat, poultry, eggs, fish, cheese, spinach, and tofu contain tryptophan amino acids. Our body uses these tryptophan amino acids to produce serotonin, which causes drowsiness.


Carbohydrate-rich foods also produce serotonin and tryptophan amino acids. This is the reason why you often feel sleepy after eating carbohydrate-rich foods. According to a 2018 study, high-carb meals can lead to an increase in sleepiness (1). Specific foods like cherries can affect melatonin levels, which bananas help to relax the muscles.

3. Dehydration

Lack of water can also lead to a slump in your energy levels after meals. Make sure that you drink enough water during the day to ensure high energy levels.

4. Overeating

Eating large quantities of food during mealtime can also lead to lethargy and make you sleepy. After our meal, your body streams more blood to the digestive system to help you digest your food. This process causes temporary blood and nutrient shortage in the brain.If you eat small amounts of healthy food, you will feel energized. If you have large meals that contain unhealthy food, you are most likely to feel drowsy post-meal.

Eat four or five smaller meals during the day to help your body to digest the food better and keep you energized.

5. Bad sleeping patterns

Not getting enough restful sleep during the night can cause sleepiness post-meal. When you are full after the meal, your body feels like relaxing, which results in sleepiness. This sleepiness is even more pronounced if you have not had a good sleep the night before.

Regular physical exercise and reducing stress can help improve sleeping habits. You must have a fixed schedule for your sleep and avoid taking naps during the day time — practice yoga and meditation to help you sleep better at night.

6. Food allergies

Certain foods can cause an allergic reaction, the symptoms of which include fatigue and sleepiness. When you ingest such foods, your body has to expend extra energy to expel these allergens. Fatigue sets in when your immune system works hard to protect your body. Check with your doctor to see if some allergen in your food is causing fatigue.

7. Diabetes

If someone with diabetes or prediabetes feels tired after eating, it may be due to hyperglycemia or hypoglycemia. Hyperglycemia occurs when you consume too much sugar. When there isn’t enough insulin to transport sugar to the cells for energy, it is worse. This is the reason why inefficient or insufficient insulin may make you feel tired.

Hypoglycemia occurs when you consume easily digestible simple carbohydrates. These carbs cause blood sugar spikes, which is followed by a blood sugar crash. Hypoglycemia can also occur in people who have taken too much insulin medication. Sleepiness is one of the primary symptoms of hypoglycemia.

8. Other health conditions

Celiac disease, anemia, sleep apnea, and inactive thyroid can also make you sleepy post-meal. If you are deficient in specific nutrients, this can also cause drowsiness after a meal. Nutritional deficiencies make it difficult for the food to be digested properly.

9. Marijuana and alcohol use

Both marijuana and alcohol can make you tired, especially after meals. Fatigue and sleepiness are the side effects of THC, the primary psychoactive compound in marijuana. Drinking alcohol during or after meals can intensify sleepiness during day time and worsen your quality of sleep during the night.

How to stop feeling tired?

Feeling sleepy and fatigues after a meal can be frustrating, especially if you have to work and need to be alert. Drowsiness can be risky for people who have to drive or operate heavy machinery.  A 2017 study examined the effect of eating during the simulated night shift on performance and subjective complaints. The results showed that the workers who ate at night performed worse and were sleepier at 4 am than those who had not eaten (2).

Try the following tips to prevent feeling tired and sleepy after meals –

  • Eat small meals frequently – Avoid large meals and eat smaller meals and snacks throughout the day. Five to six small meals are much better than three large meals.  A small bowl of fruits or a handful of nuts can keep your energy levels up.
  • Eat the right food – Eat a balanced diet that includes vegetables, whole grains, and fatty fish. Add nuts, seeds, and olive oil to your meals.
  • Sleep well – You must ensure that you get enough good-quality sleep. Sticking to a regular sleeping schedule, avoiding gadgets during sleep time, and lowering stress can improve your sleep. A person who gets a good night’s rest is less likely to have post-meal sleepiness.
  • Exercise – A few minutes of light exercise during the day after your meals can help you stay energized and prevent drowsiness. Walk for a few minutes after your lunch to avoid sleepiness.
  • Bright light therapy – Exposure to bright light after lunch can reduce tiredness and improve cognitive performance.
  • Avoid alcohol – Avoid consuming alcohol with your meals as alcohol can make people more tired and sleepy.
  • Hydration – Drink plenty of water during the day to prevent tiredness.

When to check with the doctor?

If you are constantly feeling tired and this is affecting your day to day life, it is time to check with a doctor. Tiredness and sleepiness can be the result of several medical conditions like –

  • Nutritional deficiency
  • Anemia
  • Diabetes
  • Insomnia
  • Food intolerances
  • Allergies
  • Celiac disease


The first step towards finding why you get so sleepy after a meal is to keep a food diary. Note down the details of what you eat and drink and study the impact it has on your energy levels. This process will help you to identify the foods or ingredients that trigger tiredness.

Maintain this dairy for a few weeks. Record all that you eat or drink and when you eat it in the diary. Note down how the foods affect your energy levels, mood, sleep quality, and digestive health. Note down any symptoms that you may feel during this time. This record will help your health practitioner to identify the food that may be causing your fatigue. Several diagnostic tests can also help to identify the cause of fatigue in a person. These include:

  • The hemoglobin A1C test
  • The glucose tolerance test
  • Blood glucose test
  • Blood or skin test for food sensitivities or allergies
  • Elimination diet

Final thoughts

Many people feel tired or drowsy after eating their meals. Heavy meals or meals that are rich in carbohydrates and proteins that contain tryptophan amino acids are more likely to make you sleepy. In most cases, the fatigue and sleepiness is the body’s natural response to the digestion.

There are many ways in which you can prevent sleepiness after meals. These include eating small and frequent meals, eating a balanced diet and avoiding processed and sugary foods, and staying hydrated. You must avoid alcohol and improve your sleeping patterns.


In some cases, this drowsiness and lethargy may be a symptom of a medical condition. Diabetes, anemia, nutritional deficiencies, celiac disease, insomnia, food intolerances, and allergies can also cause tiredness and sleepiness. In such cases, you must consult with a doctor.

There are several different ways to diagnose the root cause of constant fatigue and tiredness. These include the hemoglobin A1C test, glucose tolerance test, blood glucose test, blood or skin test for food sensitivities or allergies, an elimination diet.


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