What is it called when you get sleepy from food?

December 21, 2025 •

4 min read

According to the Cleveland Clinic, feeling tired after a large meal, or experiencing a "food coma," is a real phenomenon known as postprandial somnolence. While many people associate this drowsy state with certain foods like turkey, the truth is that a complex interplay of physiological factors is responsible for what is called when you get sleepy from food.

Quick Summary

The drowsy feeling after eating is medically termed postprandial somnolence, or colloquially, a food coma. It is caused by hormonal shifts, changes in blood sugar, and the body's natural circadian rhythm, especially after a large meal. This temporary lethargy can affect concentration and energy levels for a few hours.

Key Points

Postprandial Somnolence: The medical term for feeling sleepy after eating is postprandial somnolence, often referred to as a "food coma".
Complex Causes: Sleepiness is triggered by a combination of factors, not just one food, including the size and content of the meal, hormonal shifts, and the body's circadian rhythm.
Hormonal Influence: The amino acid tryptophan, found in protein-rich foods, helps produce the sleep-regulating hormones serotonin and melatonin, contributing to drowsiness.
Blood Sugar Swings: Meals high in refined carbs can cause blood sugar to spike and then crash, leading to a sudden dip in energy.
Strategic Habits: Combat sleepiness by eating smaller, more balanced meals, taking a short walk after eating, and prioritizing good sleep hygiene.
Underlying Issues: While usually harmless, persistent and excessive post-meal fatigue could signal an underlying health issue like diabetes and should be discussed with a doctor.

Understanding Postprandial Somnolence: The "Food Coma"

While colloquially known as a "food coma," the medical term for feeling sleepy after eating is postprandial somnolence. This temporary state of drowsiness, lethargy, or decreased energy can affect anyone, especially after a heavy or high-calorie meal. Scientists still don't have a single definitive answer for its cause, but they have identified several key factors that contribute to this physiological response.

The Role of Meal Size and Composition

One of the most significant factors influencing post-meal sleepiness is the size and composition of your meal. Large, calorie-dense meals are known to be a powerful trigger for postprandial somnolence. The body requires a large amount of energy for digestion, and the heavier the meal, the more work your digestive system has to do.

Carbohydrates: Consuming a meal rich in carbohydrates, particularly refined carbs, can cause a rapid spike and subsequent crash in blood sugar levels. This can lead to a sudden dip in energy, contributing to fatigue.
Proteins: Protein-rich foods contain the amino acid tryptophan. While famously associated with turkey, tryptophan is found in many protein sources. When combined with carbohydrates, this amino acid is more readily absorbed into the brain, where it is used to produce the sleep-regulating hormones serotonin and melatonin.
Fats: Meals that are high in fat content have also been linked to increased feelings of fatigue after eating.

Hormonal and Nervous System Shifts

Eating triggers a complex cascade of hormonal and nervous system changes that promote a state of rest and digestion. The body naturally shifts from a sympathetic "fight-or-flight" state to a parasympathetic "rest-and-digest" mode after eating, which can lower overall energy and increase the desire to be at rest.

Serotonin and Melatonin: As mentioned, the production of these hormones increases after a meal, with serotonin regulating mood and sleep cycles, and melatonin promoting sleepiness.
Orexin Inhibition: The hormone orexin, which is associated with hunger and wakefulness, is inhibited after you eat. This reduction in a wake-promoting hormone contributes to the feeling of lethargy.
Cytokines: High-calorie meals can cause the release of small proteins called cytokines, which have been linked to fatigue.

Natural Circadian Rhythm and Digestion

Meal timing is also a crucial factor. Most people experience a natural dip in alertness in the early to mid-afternoon, which is part of the body's internal 24-hour clock, or circadian rhythm. A large lunch eaten during this time will amplify this natural low, making the effects of postprandial somnolence even more noticeable.

Comparison of Sleepiness Triggers


Trigger	Primary Cause	Type of Food	Contributing Factors
Hormonal Shift	Increased serotonin and melatonin; inhibited orexin	High-carb and high-protein meals	Meal size, digestion, individual differences
Blood Sugar Fluctuation	Rapid spike and crash of glucose levels	Refined carbohydrates and sugars	Lack of fiber, large portion size, underlying health conditions
Meal Size	Heavy digestive workload; hormonal release	Calorie-dense, high-carb/fat/protein meals	Inadequate sleep, concurrent alcohol consumption
Circadian Rhythm	Body's natural afternoon dip in alertness	Not food-dependent, but amplified by large meals	Insufficient sleep, irregular sleep schedule

How to Combat Postprandial Somnolence

For those who need to stay alert after a meal, especially during work hours, there are several simple strategies to mitigate post-meal sleepiness:

Eat Smaller, More Frequent Meals: This helps prevent the digestive system from becoming overwhelmed and keeps energy levels more stable throughout the day.
Choose Balanced Meals: Opt for complex carbohydrates, lean protein, and plenty of fiber. This slows down glucose absorption and prevents drastic blood sugar spikes and crashes.
Take a Post-Meal Walk: A short 10- to 15-minute walk can help regulate blood sugar levels and provide an energy boost. Bright natural light can also increase alertness.
Stay Hydrated: Dehydration can contribute to fatigue, so make sure to drink plenty of water throughout the day.
Prioritize Quality Sleep: Ensuring you get 7–8 hours of quality sleep per night is essential, as sleep deprivation can significantly worsen the post-meal dip.

Conclusion

Feeling drowsy after eating is a common and usually harmless physiological response known as postprandial somnolence. It is not caused by one single factor but is the result of a combination of the meal's size and composition, hormonal changes, and the body's natural circadian rhythms. By making simple adjustments to your eating habits and overall lifestyle, you can effectively manage this phenomenon and maintain your energy levels throughout the day.

For more information on the intricate connection between diet and sleep, you can explore resources like the Sleep Foundation. If you find that persistent fatigue after meals significantly impacts your daily life, it is always wise to consult a healthcare provider to rule out any underlying medical conditions, such as diabetes or a sleep disorder.

Frequently Asked Questions

The official medical term for a food coma is postprandial somnolence. The word 'postprandial' means 'after a meal,' and 'somnolence' refers to 'drowsiness'.

The idea that turkey alone makes you sleepy is a myth. While turkey contains the amino acid tryptophan, which can produce sleep-inducing hormones, the amount is not significantly higher than in many other common foods. The sleepiness after a large Thanksgiving meal is more likely due to a combination of high carbohydrates and large portion sizes.

Large meals require a significant amount of energy to digest, and the body's focus shifts to the digestive system. This, combined with the release of specific hormones and shifts in your nervous system, promotes a state of rest, leading to feelings of lethargy and sleepiness.

Eating refined carbohydrates can cause a rapid increase in blood sugar, prompting the release of insulin. This is often followed by a crash in blood sugar levels, which results in a dip in energy and fatigue.

Yes, it is a very common and normal physiological response to eating, especially after a large meal. However, if the sleepiness is severe, prolonged, or interferes with daily life, it may be worth consulting a healthcare provider to check for underlying issues.

To prevent post-meal sleepiness, you can try eating smaller, more balanced meals, limiting alcohol, staying hydrated, getting regular exercise, and ensuring you have sufficient nightly sleep.

While occasional post-meal sleepiness is normal, frequent or severe fatigue after eating, especially when accompanied by other symptoms like increased thirst or urination, could potentially be a sign of diabetes or issues with blood sugar control. It is best to speak with a doctor if you have concerns.