How to prevent post-meal sleepiness through diet: Tips for choosing and eating your lunch

Why do I feel sleepy after lunch?

Do you find yourself unable to stop yawning during meetings after lunch, or reading the same line over and over? In this article, we explain the background behind post-meal drowsiness and countermeasures you can take with your diet, based on research and official documents.

Common situations where your eyelids feel heavy after lunch

After you finish lunch and return to your seat, your eyelids start to feel heavy. There may even be days when the sleepiness is so intense that it feels unbearable. According to explanatory materials from the Ministry of Health, Labour and Welfare, the 2019 National Health and Nutrition Survey found that among approximately 5,700 people aged 20 and over, 34.8% had experienced daytime sleepiness three or more times a week in the past month. This figure represents general daytime sleepiness, not just after meals. Even so, it calculates to more than one in three people feeling sleepy during the day.

Research showing no difference in sleepiness, even with lower blood glucose levels

A paper published in the Journal of the Japanese Society for Food Science and Technology compared blood glucose levels and sleepiness after consuming low-carbohydrate and high-carbohydrate meals. The results showed that blood glucose levels were significantly lower after the low-carbohydrate meal at all nine measurement points up to 120 minutes post-meal. On the other hand, there was no statistically significant difference in sleepiness ratings between the two meals. It is recommended to review the overall composition of your meals rather than focusing only on blood glucose levels.

Incidentally, in an experiment where 16 adult men (8 lean, 8 obese) were given an interleukin-1 receptor antagonist after running for 30 minutes before consuming a high-fat/high-carbohydrate meal, post-meal fatigue was reduced, with the reduction being greater in the obese group. However, this was not a study on sleepiness itself, and because it involved a combination of exercise and medication, the results cannot be applied directly to ordinary meals.

Afternoon sleepiness is natural. There are also reasons other than diet, such as lack of sleep.

Ministry of Health, Labour and Welfare materials state that it is natural to feel a certain level of sleepiness in the early afternoon, and that lack of sleep increases daytime drowsiness. Furthermore, the ministry's explanatory materials indicate that causes of sleepiness include not only lack of sleep, but also sleep disorders, the effects of medication, and mental health conditions. When you decide to change your lunch, try reflecting on your sleep from the night before as well. If you find yourself feeling like you've overeaten consistently, it is recommended to slightly reduce your portion sizes and see how you feel.

When you're concerned about post-lunch sleepiness, what foods should you add, and which staples should you reconsider?

On days when post-lunch sleepiness bothers you, it is easier to start by "adding" foods. Based on research and official documents, we will introduce protein-rich foods to add to lunches consisting only of rice balls or sweet bread, as well as vegetables, seaweed, and mushrooms that provide dietary fiber.

Adding protein to lunches consisting only of rice balls and sweet bread

There are days when you finish a busy morning and eat two rice balls and a sweet bun at your desk. It’s convenient, but these are all staple carbohydrates. They lack main dishes like meat, fish, eggs, or soy products.

We recommend adding items like salad chicken, boiled eggs, natto, tofu, or canned mackerel. Since these can all be eaten immediately after purchase, adding just one side dish to your rice balls means your lunch is no longer just staples. Canned mackerel can be stored at room temperature, making it convenient to keep in your desk drawer for days when you couldn't prepare a side dish.

As for the reason for combining staples with a main dish, let us introduce one study. A cross-sectional study published in the Journal of the Japanese Society of Health Education and Promotion surveyed 1,781 people aged 20 to 95. A correlation was found where both men and women who almost daily ate meals combining a staple, main dish, and side dish perceived their health as good. The adjusted odds ratio was 1.71 for men and 1.82 for women. An odds ratio greater than 1 indicates that more people who ate those meals answered "good."

However, this study did not investigate sleepiness. Since it was a study examining the situation at a single point in time, it cannot be said that the combined meal was the cause of the improved feeling of health. This information is not a promise of an effect on sleepiness, but rather should be taken as a point of reference when trying the format of adding one main dish to a staple-only lunch.

Adding dietary fiber with vegetables, seaweed, and mushrooms

On days when you buy sweet bread and rice balls, you won't see any vegetables even after opening the bags. In such cases, adding one dish like a pre-cut salad, vinegared mozuku seaweed, marinated mushrooms, or wakame soup can add dietary fiber.

There is a daily intake target for dietary fiber. However, this is not a standard for reducing post-meal sleepiness. It is recommended to use it as a guideline to ensure you don't run out of vegetables, seaweed, and mushrooms in your daily diet.

If you want to check the amount of dietary fiber in numbers, look at the nutritional information label. According to the Consumer Affairs Agency, labeling of carbohydrates is mandatory for general processed foods in containers and packaging, while labeling of dietary fiber is recommended. Since dietary fiber is not mandatory, some products may not have a column for it.

If you cannot find a column, choose products based on whether vegetables, seaweed, or mushrooms are listed in the ingredients. Trying to add just one salad or small side dish allows you to continue without significantly changing your lunch routine.

Reconsidering the type and amount of your staple food

On days when you eat rice balls for lunch and add a sweet bun or udon, your meal tends to be all staples. If you are concerned about sleepiness, first try reconsidering the type and amount of your staple food.

There is a study comparing types of sugar. In a 2013 paper published on PubMed, 44 healthy adults ingested 75g each of the low-GI carbohydrate isomaltulose and glucose, and the results were compared. It was a randomized crossover study where the same people ingested both. The results showed that the assessment of mental and physical energy states and physical fatigue 4 to 5 hours after ingestion was significantly better with isomaltulose.

However, this study did not evaluate sleepiness. Also, since it was an experiment using a sugar called isomaltulose, it does not apply directly to rice or bread. All that can be said is that there are research reports showing that the evaluation of how the body feels several hours later changes depending on the type of sugar consumed.

For actual lunches, we recommend trying to change just one type of staple food. For example, you can switch white rice to multi-grain rice or barley rice, or swap bread for rice balls. Keep the portion size the same as usual and make a quick note of how you felt during the afternoon. Since there are reasons for sleepiness other than diet, such as lack of sleep, try changing only one thing at a time so you know which change you were testing that day.

If you often double up on staples, try stopping the practice of lining up two types of staples, like rice balls and bread, and stick to one. If you want to find out why your sleepiness varies from day to day, please also refer to Is afternoon sleepiness caused by blood glucose levels? How to tell and how to review your lunch.

How will you change tomorrow's lunch at a convenience store, company cafeteria, or with a packed lunch?

Whether at a convenience store or a company cafeteria, the contents of your lunch change depending on how you choose. Using the "unit" (SV) from the Dietary Balance Guide as a clue, we will introduce concrete examples of how to rearrange tomorrow's lunch from "before change" to "after change," broken down by convenience store and company cafeteria/set meal settings.

At a convenience store, stick to one staple and add side dishes and soup

The Dietary Balance Guide counts dishes using a unit called "tsu" (SV). According to the Ministry of Agriculture, Forestry and Fisheries food classification, one staple is about one convenience store rice ball, one side dish is one small bowl, and one main dish is about one egg or one pack of natto. Once you understand that one rice ball, one side dish, and one egg each count as "one," it will be easier to compare quantities in front of the shelves.

The Ministry of Health, Labour and Welfare's Dietary Balance Guide sets the daily guideline for adults with an energy requirement of approximately 2,200–2,400 kcal as 5–7 staples, 5–6 side dishes, and 3–5 main dishes. However, this is a daily guideline, not a standard for a single meal. Necessary amounts also vary by person.

For a convenience store lunch, it is easier to assemble if you limit yourself to one staple and add main and side dishes with the space saved. How much the price increases with the added item depends on the store and the product. Returning the sweet bun or cup noodles to the shelf and swapping them for an egg or soup makes it easier to estimate the cost increase.

At a company cafeteria or for a set meal, decide on the amount of rice and the combination of side dishes

At a company cafeteria counter, rice bowls or noodle sets often catch the eye, and it's easy to just get in line for them. If you decide what you'll have—rice, main dish, small bowl, and soup—while waiting in the serving line, you can pick them up without hesitation.

According to the Ministry of Agriculture, Forestry and Fisheries' food classification, one standard serving of fish is about two main dishes, and one serving of meat is about three main dishes. Since you can expect enough main dish volume from one plate, the rest can be adjusted by the amount of rice and the small side dish.

• Bowl dish only → Make it a set meal, keep the rice as a regular serving, and add a small side dish and soup.
• Ramen and half fried rice → Keep the ramen and add a small salad or egg dish.
• Fried food set meal with large rice → Swap to a fish set meal with regular rice and add an extra side dish.

If the cafeteria lets you choose the amount of rice, start by remembering that one rice ball equals one staple and switch from a large serving to a regular one. Noodle and bowl dishes contain both a staple and a main dish on one plate. Therefore, adding a side dish or soup brings you close to a balanced set meal combination.

A company cafeteria where you can choose the menu every day is a place where it's easy to try changes. First, try adding one small side dish to today's lunch; if you can keep that up, it’s not too strenuous to review your rice portion the following week.

Assembling methods you can also use for homemade bento and eating out

Homemade bentos and eating out are lunches where you can decide the contents yourself. You don't have to choose from items already lined up; just changing one aspect of how you pack or order will change the overall composition.

Setting	Before Change	After Change
Homemade Bento	Rice and frozen croquette	Slightly reduce rice, add grilled salmon, rolled omelet, and broccoli
Bowl Dish	Large beef bowl	Regular beef bowl, add pork miso soup and a small side of spinach
Pasta/Ramen	Noodle dish only	Add a salad or boiled egg

For bentos, using leftovers from the previous night's dinner saves effort. If you have leftover grilled salmon or teriyaki chicken, use that as your main dish, and we recommend adding frozen broccoli or cherry tomatoes. Reduce the rice slightly to account for the extra side dishes.

Eating out is assembled at the time you order. Rather than menus completed on one plate like rice bowls or ramen, a set meal that includes rice, a main dish, a small side dish, and soup requires less hassle in placing additional orders. On days when you want to eat a single-dish meal, try adding one salad, small side dish, or soup.

For those who snack because they get slightly hungry in the afternoon, please also refer to What is the relationship between concentration, food, and snacks? How to choose based on blood glucose levels and sleepiness.

How to prepare for post-meal sleepiness by changing the order and pace of eating?

You can change how you eat lunch even if the contents remain the same. Tips such as starting with soup or vegetables, chewing slowly, deciding on portion sizes, and not skipping lunch are useful. We will introduce these four tips along with personal experiences and official documents.

Start eating from soup or vegetables

Once you sit down at the cafeteria, try using your chopsticks for the miso soup or the small vegetable side dish before touching the rice.

One personal post notes that as a countermeasure for post-lunch sleepiness, eating soup or vegetables first and eating slowly helped make the wave of sudden drowsiness much milder. This is one person's experience and not evidence that applies to everyone.

There is also research on eating order. In a 2020 paper published on PubMed, 16 healthy Chinese adults ate vegetables, chicken breast, and white rice in five different orders, and changes in post-meal blood glucose and insulin were compared over 3 hours. The results showed that significant differences in the passage of time were observed depending on the order. Since sleepiness was not measured, this does not serve as evidence for effects on drowsiness.

All you need to change is the first bite. If at a convenience store, it's a good idea to eat the salad or soup first before moving on to the rice ball.

Chew slowly and thoroughly, and stop at 80% full

There are days when you only have a 20-minute lunch break and end up finishing in 5 minutes. On such days, try putting down your chopsticks after every bite and swallowing what's in your mouth before proceeding to the next.

Eating slowly was also incorporated in the personal post mentioned earlier. You don't need to count how many times you chew. If you don't have time, just cutting the side dish into smaller pieces before putting them in your mouth will slow your pace. On days when you have a meeting or driving to do in the afternoon, try to be conscious of finishing your meal before you feel completely full.

The relationship between portion size and sleepiness cannot be guaranteed to have a specific effect. Even so, finishing a meal leaving a little room instead of stuffing yourself is recommended for those who want to spend their afternoon feeling light. If you are still hungry, you can adjust with an afternoon snack.

Do not skip lunch, and do not overly reduce carbohydrates

There may be days when you halve your lunch rice or skip lunch entirely because you don't want to get sleepy.

Ministry of Health, Labour and Welfare materials set the target for adult carbohydrate intake at 50–65% of total energy intake. It is explained that the required amount of carbohydrates is unknown, and the target was set from the perspective of energy sources. For someone who needs 2,000 kcal per day, this corresponds to 1,000–1,300 kcal.

This is a guideline for the entire day, not a standard for lunch alone. However, if you minimize rice, bread, or noodles, it is easy to fall below this range. Since there is research showing no difference in sleepiness even with reduced-carbohydrate meals, there is likely no need to reduce them extremely.

On days when you are concerned about sleepiness, it is important not to skip lunch, to keep the staple food to about one light bowl, and to combine it with side dishes and soup.

What should you do if you get sleepy immediately after eating?

We will introduce three ways to handle sleepiness when it hits before an afternoon meeting or task begins. We explain caffeine intake timing and amount, getting up to move and bathe in light, and short naps during lunch breaks, in line with how to spend your time after lunch.

Decide on the amount and timing of coffee consumption

There are days when you want to have a cup of coffee before an afternoon meeting to prepare for sleepiness. The Ministry of Health, Labour and Welfare's sleep guide indicates a daily caffeine intake of within 400mg and suggests refraining from it after the evening. Furthermore, EFSA states that even a single 100mg dose of caffeine can affect the sleep duration and sleep patterns of some adults if consumed close to bedtime. It is a good idea to drink coffee after lunch until early afternoon and decide how many cups to have in a day.

Get up, walk around, and bathe in light

After you finish lunch, don't just return to your seat; stand up first. If you're in an office, walking the corridors or stairs for a few minutes is sufficient. On days you can go outside, we recommend walking around the building once. Spending time in a bright location, such as by a window or outdoors, makes it easier to shift your mood. If your next schedule is a meeting, choosing a slightly longer route to the meeting room is also an easy method.

Take a short 10–15 minute nap

If you have some flexibility during your lunch break, we recommend a 10–15 minute nap. You can just close your eyes while sitting in your chair. Even if there is no place to lie down, resting quietly at your desk is enough. If you set a smartphone alarm for 10–15 minutes ahead, you can rest without worrying about oversleeping.

When should you seek advice if strong sleepiness continues even after reviewing your diet?

If strong sleepiness that interferes with work or driving continues even after reviewing your diet and eating habits, there may be reasons other than diet. You can learn about signs of sleepiness that warrant consultation and how to prepare records before a medical visit.

Signs of strong, persistent sleepiness regardless of diet

If you have days where your consciousness repeatedly lapses during meetings or you have dangerous experiences due to sleepiness while driving, even after reviewing your diet, treat this separately from the natural afternoon sleepiness mentioned earlier. The Ministry of Health, Labour and Welfare's "Daytime Sleepiness" recommends that if strong daytime sleepiness or falling asleep interferes with studies or work, you should undergo examination and treatment at a medical institution specializing in sleep disorders.

Additionally, the National Center of Neurology and Psychiatry states that consultation with a doctor is necessary if excessive daytime sleepiness or falling asleep interferes with work or driving, or if there is repeated heavy snoring or breathing cessation during sleep. If you live with family, it's a good idea to ask if they have noticed you snoring or stopping breathing while asleep.

Record your sleep time and times of sleepiness for consultation

If you are getting enough sleep but still have strong daytime sleepiness, or if you fall asleep suddenly, consulting with your primary care physician or a sleep specialist is recommended. The center's Support Manual for Sleep Disorders and Sleep Problems suggests bringing a sleep record of about two weeks if possible.

In the record, write down the time you went to bed, the time you woke up, and the time when your sleepiness was strong. A notebook or smartphone memo is sufficient. Adding a brief note about the contents of your lunch will make it easier to tell your doctor how your sleepiness differed before and after changing your diet. On days when you are concerned about sleepiness, we recommend starting a record first.

Why choose BRAIN PRO for an afternoon snack? Component comparison with commercial bars

When choosing an afternoon snack, you can learn how to read labels for carbohydrates, net carbs (sugars), and dietary fiber. Along with that, we will introduce the components per bar of BRAIN PRO and how to view them when comparing with commercially available protein bars.

How to read carbohydrates, net carbs (sugars), and dietary fiber on nutrition labels

According to Consumer Affairs Agency materials, labeling of carbohydrates is mandatory for general processed foods in containers and packaging, while labeling of dietary fiber is recommended. Sugars are components that can be labeled optionally. Therefore, some products do not list sugars or dietary fiber. First, look at the carbohydrate value, and if net carbs (sugars) and dietary fiber are both listed, confirm the breakdown. BRAIN PRO's 7.1g of carbohydrates consists of 4.9g of net carbs (sugars) and 2.2g of dietary fiber.

Comparing BRAIN PRO components with commercial bars

Product	Contents	Net Carbs	Artificial Sweeteners	White Sugar	Protein (Source)
Myprotein Layered Protein Bar Birthday Cake	60g	21g	Used (Sucralose)	Used	20g / Milk, Soy
in Bar Protein Crunchy Chocolate	43g	11.7g	Not Used	Used	17.9g / Soy, Milk
SOYJOY Calorie Control 80 Blueberry	17.8g	6.7g	Not Used	Used	2.4g / Soy
ZAVAS Protein Bar 1/2 Day's Iron Royal Milk Tea Flavor	38g	Not listed (Sugars 6.4g)	Used (Sucralose)	Used	14.7g / Milk, Soy
BRAIN PRO	35g	4.9g	Not Used	Not Used	11.1g / Plant-based (Pea)

Values for each product are based on nutritional information posted on each manufacturer's official website as of September 25, 2026. Values may change due to product revisions.

BRAIN PRO contains 190 kcal, 11.1g of protein, 13.5g of fat, and 0.4g of salt equivalent per 35g bar. Ingredients include almond paste, pea protein, and almonds, and it contains no white sugar or wheat. Differences become clear when you write down the same items from the packages of commercial protein bars and compare them. For those who want to avoid white sugar and wheat, BRAIN PRO is recommended. However, since it contains soy and almonds as ingredients, those with allergies to these should be careful.

Frequently Asked Questions

What foods don't make you sleepy after a meal?

It cannot be said that sleepiness will disappear just through food alone. Afternoon sleepiness is natural, and there are reasons other than diet, such as lack of sleep. With that in mind, we recommend changing how you assemble your lunch. On days when you only have rice balls or bread, add one protein dish like eggs, natto, or salad chicken, and one side dish like salad or soup. Do not line up two types of staple foods; stick to one. Change only one thing at a time, and making a quick note of afternoon sleepiness makes it easier to understand the results of your trial.

How can I eliminate post-meal sleepiness?

While there is no single way to eliminate it, there are ways to prepare. For lunch, start eating from soup or vegetables, and chew slowly, putting down your chopsticks after every bite. It is also recommended to put down your chopsticks before you are full. However, it is important not to skip lunch or extremely reduce your staple food. After eating, get up from your seat and walk for a few minutes, and spending time in a bright place makes it easier to transition. If you have time, try incorporating a 10–15 minute nap. Also, reflect on your sleep time from the previous night.

Are there foods that blow away sleepiness?

It cannot be said that there are foods that will blow away sleepiness just by eating them. For those who want to use caffeine, such as coffee, for afternoon sleepiness, please use the Ministry of Health, Labour and Welfare's sleep guide as a guideline. It indicates a daily caffeine intake of within 400mg and suggests refraining from it after the evening. If you drink it, stick to the time from after lunch until early afternoon, and it is recommended to decide on the number of cups per day in advance. If strong sleepiness continues even then, please keep a record of your sleep and sleepiness and seek consultation.

Summary

Post-meal sleepiness can be tested through small changes, such as adding one dish to lunch, sticking to one type of staple food, or making the first bite of your meal soup or vegetables.

Since sleepiness is not determined solely by diet, you should also review your sleep from the night before and how you spend your time after lunch.

If sleepiness that interferes with work or driving continues even after changing your diet, we recommend seeking consultation while carrying a record of your sleep and sleepiness.

For tomorrow's lunch, please try changing just one thing first.