Many people feel sleepy after eating. This can be a natural result of digestion patterns and sleep cycles.

Some types of foods and the timing of meals can also make people feel especially tired after a meal. A decrease in energy levels after eating is called postprandial somnolence.

Researchers have different theories about the cause of tiredness after eating, but they generally agree that it is a natural response and not usually a cause for concern.

Feeling tired, or having difficulty concentrating, after a meal is relatively common. A person may feel particularly tired, depending on what, when, and how much they ate.

Below, we discuss some reasons why a person might feel tired after a meal, and how to prevent it.

The type of food you eat

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Meals containing both carbohydrates and protein can make a person feel tired.

Foods rich in protein and carbohydrates can make people feel sleepier than other foods.

Some researchers believe that a person feels tired after eating because their body is producing more serotonin.

Serotonin is a chemical that plays a role in regulating mood and sleep cycles.

An amino acid called tryptophan, which occurs in many protein-rich foods, helps the body produce serotonin. Carbohydrates help the body absorb tryptophan.

For these reasons, eating a meal rich in both protein and carbohydrates may make a person feel sleepy.

Tryptophan occurs in foods that are rich in protein. These include:

  • salmon
  • poultry
  • eggs
  • spinach
  • seeds
  • milk
  • soy products
  • cheese

Foods that contain high levels of carbohydrates include:

  • pasta
  • rice
  • white bread and crackers
  • cakes, cookies, donuts, and muffins
  • corn cobs
  • milk
  • sugar and candy

People often eat a combination of protein and carbohydrates before bed, such as cereal with milk.

How much food you eat

A person may be likelier to experience postprandial somnolence after a large meal.

People who eat larger lunches may experience more of an afternoon slump than those who eat less at midday. Eating causes blood sugar to rise, and a dip in energy may follow.

Other factors can contribute to tiredness after eating:

  • poor sleep at night, which can lead to tiredness throughout the day
  • drinking alcohol with a meal, especially during the daytime

When you eat meals

A person’s natural body clock, or circadian rhythm, can affect how they feel after eating.

The National Sleep Foundation report that people naturally have a lull in energy 2 a.m. and again at 2 p.m. This may explain the tradition of taking a nap, or siesta, after the midday meal.

Daylight and darkness are essential in regulating the circadian rhythm, but the timing of meals may also have an effect.

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Getting enough high-quality sleep can help prevent tiredness after eating.

Feeling tired after a meal can be frustrating, especially after lunch, when a person may need to be alert.

A drop in energy during the day can be particularly dangerous for people who work in risky conditions, such as those who operate machinery or vehicles.

A 2017 study of the effects of eating on the performance of night shift workers found that those who ate at night performed worse and were more sleepy at 4 a.m. than those who had not eaten.

The following strategies can help prevent tiredness after a meal:

  • Eat little and often. Rather than eating big meals, eat smaller meals and snacks every few hours to keep up energy levels. A piece of fruit or a handful of nuts should be enough to cure an energy dip.
  • Get good-quality sleep. A person who gets enough sleep at night is less likely to experience a significant post-lunch energy dip.
  • Go for a walk. Getting light exercise during the day, especially after eating, can help people feel less tired.
  • Take a short nap during the day.
  • Try bright-light therapy. Authors of a 2015 study found that exposing people to bright light after lunch reduced tiredness.
  • Avoid drinking alcohol with meals. Alcohol can make people feel more tired.

If a person is continually tired after eating, and it is affecting their quality of life, they should speak to a doctor.

The following medical conditions could contribute to excessive tiredness after eating:

Many people experience a dip in energy after eating. Large meals and meals rich in protein and carbohydrates are most likely to make people feel sleepy.

In most cases, a dip in energy after eating is a natural biological response.

However, if this is getting in the way of daily activities, a person may benefit from changing the contents and timing of their meals. If these types of changes do not help, see a doctor.