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
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:
- soy products
Foods that contain high levels of carbohydrates include:
- white bread and crackers
- cakes, cookies, donuts, and muffins
- corn cobs
- 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.
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.