Science Based Reasons for Feeling Tired or Sleepy after Eating

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Common Causes for Feeling Tired or Sleepy After Eating (Science Based)

Feeling tired or sleepy after eating a meal is something that most of us have experienced. After we finish a large lunch or dinner, feelings of drowsiness and fatigue can make us want to go for a nap. Is feeling sleepy or tired after finishing a large meal something to worry about?

Many of the reasons why you may want to snooze after eating are to do with carbs and sugar in your meal. A large sugar crash after eating can make you feel extremely tired and want to curl up and doze off for a time. Also, it requires a lot of energy for your body to digest large quantities of food which can make you feel drained and fatigued.


Sleepiness and drowsiness are also connected with certain hormones and amino acids in your body. For example, turkey contains the amino acid tryptophan which has been linked to sleep and drowsiness. So, many people claim that eating turkey makes you sleepy because of the compound tryptophan.

In this article, you will learn about common reasons why you can feel tired or sleepy after eating. You will also find out what you can do to prevent feeling tired after lunch. We will also look at what science says about what it could be in turkey that makes you feel tired.

The Science Behind Feeling Tired and Sleepy After Eating

Food is the main source of energy that your body needs to function properly. As soon as you consume food, your digestive system goes to work to break down the food and extract the nutrients. Your digestive system turns much of the food you eat into fuel or glucose.

Researchers from the University of California say that when you consume food, there is a rush or spike of insulin in the body. After this initial rush, insulin levels drop significantly which some refer to as a sugar crash.1

However, this is not the only effect that eating a meal causes. Insulin also causes tryptophan to reach the brain where it stimulates serotonin and melatonin. Both of these neurotransmitters help regulate sleep.

According to the American Journal of Clinical Nutrition, carbohydrate-rich meals increased levels of tryptophan in the blood. This, in turn, affected concentrations of serotonin in the brain. The result is a calming effect on the body which can induce drowsiness.2

Reasons Why You Feel Sleepy or Tired After Eating

Let’s look in more detail at the many reasons why eating lunch or dinner can leave you feeling tired and sleepy.

Orexin suppression

Orexin is a chemical in the body that helps to regulate wakefulness and appetite. If orexin production is suppressed, you will feel drowsy and tired.

According to researchers in the journal Frontiers in Endocrinology, adequate levels of orexin are necessary to regulate sleep and wakefulness. In extreme cases, a depletion of orexin can cause excessive daytime sleepiness.3

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The journal Diabetes reports that blood glucose levels are directly connected with orexin production. Researchers have found that high insulin levels decrease the amount of orexin the body produces. This could result in a person feeling extremely tired and drowsy after a carbohydrate-rich meal. On the other hand, lower insulin levels stimulate orexin secretion.4

So, one of the reasons for feeling extreme post-meal fatigue could be due to insulin and glucose levels suppressing orexin.

Inflammation

Another reason for feeling sleepy after lunch or dinner is if you suffer from an inflammatory condition.

Inflammation in the body causes the body to divert energy to fight the infection and source of inflammation. Researchers have discovered that inflammatory responses in the body also excrete cytokines that suppress orexin and can make you sleepy.

According to medical studies published in the Journal of Neuroscience, inflammation caused by acute illness can negatively affect orexin levels. This can have an effect of not just making you sleepy after a meal, but causing lethargy while you are ill.5

Insulin and tryptophan

Insulin spikes that happen after consuming too many sugary drinks or carbohydrates can cause an energy slump after eating.

The American Journal of Clinical Nutrition published a study showing that a high-glycemic index (GI) meals increase the amount of tryptophan in the brain. The high levels of tryptophan increase secretions of serotonin which brings on sleep.6

Interestingly, the Journal of Psychiatry & Neuroscience reports that tryptophan supplements are used to increase serotonin naturally. This is sometimes used for people who have trouble getting to sleep.7

Gut hormones

Another reason that foods can make you sleepy is due to hormones in your gut that are part of your digestive system.

One of these hormones is cholecystokinin (CCK) which can induce feelings of sleepiness after a fat-rich meal. For example, clinical trials into the effect of CCK and feelings of drowsiness after eating have shown a connection. A study in 2010 reported that increasing CCK levels after eating created a “feeding-induced sleep response.”8

Even though CCK increases orexin levels, other chemical interactions the gut cause fatigue and lethargy after eating a large meal.

Other Reasons for Being Sleepy and Drowsy after Eating

We have now looked at the reasons why all of us can feel tired and sleepy after eating. Let’s look at a few underlying health conditions that are also connected with feeling tired after eating.

Digestive disorders and feeling sleepy after eating

Some digestive disorders like irritable bowel syndrome or celiac disease can induce feelings of sleepiness after eating.

A study from China found that many gastrointestinal issues can cause drowsiness and tiredness after eating. For example, peptic ulcers, irritable bowel syndrome, and heartburn have all been linked to daytime sleepiness. Individuals who have one or more digestive problems also showed more symptoms of daytime lethargy.9

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Fortunately, there are many effective home remedies for all sorts of digestive disorders. For example, many herbal teas have an anti-inflammatory effect on the gut and can help to soothe problems with digestion.

Obesity

People who are overweight tend to feel sleepier after eating carbs or large meals than people who have a healthy weight.

Of course, the way our digestive system works can make anyone feel like taking a nap after lunch or dinner. But, research into daytime sleepiness has found that overweight people are more commonly affected.

The journal Sleep published research into the effects of obesity and sleepiness. It found that hypersomnolence (excessive daytime sleepiness) significantly affects individuals who are overweight. It was discovered that obesity affects metabolism and neurons that are responsible for wakefulness.10

You can start losing weight by increasing the amount you walk every day as well as trying these 12 simple tweaks for weight loss.

Type 2 diabetes

Because eating foods that spike sugar levels can make you feel drowsy after eating, it’s no surprise that diabetics also suffer from needing to take a nap after eating.

The Journal of Psychosomatic Research reported that increased sugar levels can bring on feelings of tiredness and fatigue. In fact, tiredness was one of the most common symptoms of elevated blood glucose levels. This also affected cognitive function and altered mood states.11

The symptoms of a sugar crash and feelings of extreme tiredness are compounded in diabetics. Many people with type 2 diabetes have difficulty maintaining a healthy weight which can cause more feelings of tiredness after eating.

Why You Feel Sleepy After Eating Carbs

Carbs are one of the foods that make you feel sleepy in the afternoon. Why do carbs have this effect on your fatigue levels? After all, carbs are a source of energy for the body and should make us feel energized.

You get tired after eating carbs because they tend to shoot your glucose levels up. That causes your pancreas to produce insulin which in turn affects chemicals in the body that regulate sleep and wakefulness.

For example, the Western Journal of Nursing Research found that carbohydrate intake greatly affected sleep patterns. Individuals who were on a carb-rich diet fell asleep far quicker than ones on a low-carb diet.12

However, it’s important to remember that not all carbohydrates are created equal. Carbohydrates that create sharp sugar spikes and subsequent sugar crashes are simple carbohydrates.

Dr. Maryann Tomovich Jacobsen on WebMD says that simple carbs like white bread, sugar, cakes, and pasta act as quick-burning fuels in the body and quickly become sugar. The best kind of carbohydrates to eat are complex carbs such as in whole grains. So, oats, barley, whole grain bread, brown pasta, and brown rice are all examples of healthy carbs. Complex carbs contain healthy components like fiber, essential vitamins and minerals that are necessary for a healthy, well-balanced diet.13

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To find out more about low-carb diets, please read my article on what you need to know about carb-restrictive diets.

Why Sugar Makes You Sleepy

The reason that sugar makes you sleepy is for the same reason that carbohydrates make you want to take a nap after lunch. Sugar affects insulin levels which in turn decrease levels of orexin.

A study from 2008 reported that orexin is necessary to feel awake. Also this neurotransmitter is important for memory, cardiovascular control, and reducing stress. Scientists have found that even a small rise in blood glucose levels can decrease the activity of orexin.14

Reasons Why You Feel Sleepy After Lunch

There are a number reasons why many of us want to fall asleep after eating lunch. Here are the 3 most common:

  • Consuming a combination of carbohydrates and drinking sugary drinks.
  • Eating large portions of fatty meals for lunch.
  • Consuming a large number of foods that contain tryptophan.

Does Turkey Make You Sleepy?

Does science back up claims that eating a turkey dinner or having a turkey sandwich for lunch makes us sleepier than eating other foods?

A report published in the journal BMJ on myths associated with food found that turkey doesn’t make you especially drowsy. The claims that turkey makes you tired come from the fact that turkey contains levels of sleep-inducing tryptophan. However, according to the researchers, turkey contains the same amount of tryptophan as chicken and minced beef. Food like pork, cheese, and some dairy products contain more tryptophan.15

The researchers summarized that eating large Thanksgiving meals or Christmas meals with turkey, stuffing, and desserts would naturally induce more drowsiness because of the high protein and carbohydrate content. The wine accompanying the meal may also play a role in feeling drowsiness.

Is Feeling Sleepy After Lunch Caused by Lack of Blood Flow to Brain?

Another interesting claim about what makes you sleepy after a large lunch is that there is less blood flow to the brain. This, many claim, causes feelings of fatigue and tiredness. What does science say about sleepiness caused by reduced blood flow to the brain?

Although some scientists hold to the view that a lack of oxygen in the brain causes sleepiness, other studies say otherwise. The journal Medical Hypotheses say that blood flow to the brain is usually well maintained by the body in various states, including after eating a meal. Tiredness and sleepiness after eating are most likely due to the decrease of orexin, increase in melatonin and other chemicals that regulate wakefulness.16

Foods that May Make You Sleepy

Some of the foods that could make you tired and sleepy are those that contain higher levels of tryptophan.

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According to the American Nutrition Association, foods like poultry, beef, dairy products, and other high-protein sources can induce feelings of sleepiness. This happens because they stimulate the production of serotonin naturally which is known to bring on tiredness.17  

However, probably the type of food that most likely makes you very tired after eating is anything that is rich in carbohydrates and protein.

How to Avoid Feeling Sleepy After a Meal

For many people, fighting tiredness after lunch is a big challenge. What can you do to reduce feelings of being sleepy after a meal?

Eat smaller meals

One way to stop feeling tired and sleepy after lunch or dinner is to eat smaller meals. Many of the medical studies mentioned in the article have pointed to the fact that large, protein or carbohydrate-rich meals can make you tired after eating.

Drinking green tea

You may be able to avoid an energy slump after eating lunch if you combine a cup of green tea with lunch.

Green tea has many health benefits including helping to lose weight and it contains powerful antioxidants. A study published in the journal Science Reports found that green tea helps to break down carbohydrates more effectively. Green tea also reduces starch and fat absorption as well as lowering levels of blood sugar. Added to that, green tea has small amounts of caffeine which can help to give you a mental boost after lunch.18

Walking after a meal

Going for a walk after lunch will not just help keep your heart healthy and help you lose weight but will also help you feel less tired and sleepy after eating.

According to the International Journal of General Medicine, going for a brisk walk immediately after finishing a meal has many benefits. Among the benefits are helping to prevent sugar crash symptoms, feeling tired after a meal, and reducing blood glucose levels. In fact, scientists estimated that blood glucose levels can be reduced by up to 36%.19

However, for the best benefit, it was important to go for a walk straight after finishing a meal rather than waiting for 30 minutes or an hour.

Reduce carb and sugar intake

Of course, if you constantly feel very sleepy after eating carbs, you should try to reduce your intake of carbohydrates. You could try switching to whole grain foods as they release energy at a slower and controlled pace and contain many nutrients that benefit your health.

It’s also important to reduce the amount of sugar in your diet. You will find that you start to shed extra pounds quickly and may feel less tired after eating a meal.

Keep food diary

To find out which foods are making you sleepy, you could keep a food diary. This may help identify if you are affected by food intolerances or allergies that may cause you to feel tired after eating a meal.

Stay hydrated

To help your body to function properly and effectively, you should keep yourself well-hydrated throughout the day.

According to the journal Nutritional Reviews, even mild dehydration can cause feelings of fatigue, reduced motivation, and increased perceived effort.

For more information on the benefits of keeping yourself well-hydrated, please read my article on what happens to your body when you are dehydrated.

Read my other related articles:

Medical Sources

  1. UCSF. Insulin basics.
  2. Am J Clin Nutr.2003 Jan;77(1):128-32.
  3. Front Endocrinol (Lausanne). 2003 Jan;52(1):111-7.
  4. Diabetes. 2003 Jan;52(1):111-7.
  5. J Neurosci. 2011 Aug 3; 31(31): 11376–11386.
  6. Am J Clin Nutr.2007 Feb;85(2):426-30.
  7. J Psychiatry Neurosci. 2007 Nov; 32(6): 394–399.
  8. Szeged. Metabolic signals in sleep regulation.
  9. J Neurogastroenterol Motil. 2017 Apr; 23(2): 298–305.
  10. Sleep. 2012 May 1; 35(5): 605–615.
  11. J Psychosom Res. 2010 Jul; 69(1): 33–41.
  12. West J Nurs Res. 2013 Apr; 35(4): 497–513.
  13. WebMD. Your guide to eating healthy carbs.
  14. PNAS. 2008 Aug; 105(33): 11975-77980.
  15. BMJ. 2007 Dec 22; 335(7633): 1288–1289.
  16. Med Hypotheses.2004;63(5):778-82.
  17. AmericanNutritionAssociation. Focus on tryptophan.
  18. Sci Rep. 2015; 5: 12015.
  19. Int J Gen Med. 2011; 4: 447–450.
  20. Nutr Rev. 2010 Aug; 68(8): 439–458.
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One Response to Science Based Reasons for Feeling Tired or Sleepy after Eating

  1. della roth says:

    I have known for years that sugar causes a surge of calories and causes you to pass out, fall asleep, and the only way to combat it is to walk or get busy physically. why cant my husband see this and accept the truth? now he has a growth in his lower intestine and he Is so worried he refuses to acknowledge it.

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