We’ve all felt it — that drowsy feeling that sneaks in after a meal. You’re full and relaxed and struggling to keep your eyes open. Why are meals so often followed by a sudden urge to take a nap, and should you be concerned about it?
In general, a little bit of sleepiness after eating is completely normal and nothing to worry about. There are several factors that contribute to this post-meal phenomenon, and there are a few things you might be able to do to minimize those drowsy effects.
Your body needs energy to function—not just to run after your dog or put in time at the gym—but to breathe and simply exist. We get this energy from our food.
Food is broken down into fuel (glucose) by our digestive system. Macronutrients such as protein then provide calories (energy) to our bodies. More than just changing food into energy, our digestive cycle triggers all kinds of responses within our body.
Hormones such as cholecystokinin (CCK), glucagon, and amylin are released to increase a feeling of fullness (satiety), blood sugar rises, and insulin is produced to allow this sugar to go from the blood and into the cells, where it’s used for energy.
Interestingly, there are also hormones that can lead to drowsiness if increased levels are found in the brain. One such hormone is serotonin. The other hormone that induces sleep, melatonin, isn’t released in response to eating. However, food can influence melatonin production.
Though all foods are digested in much the same manner, not all foods affect your body in the same way. Some foods can make you sleepier than others.
Foods with tryptophan
Tryptophan is used by the body to create serotonin. Serotonin is a neurotransmitter that helps regulate sleep. It’s possible that increased production of serotonin is responsible for that post-meal haze.
In the United States, tryptophan is perhaps more closely associated with turkey than any other food. This is likely a result of the sleepiness sometimes associated with consuming a turkey-centric meal, as is traditional for many on Thanksgiving.
However, turkey doesn’t contain a high level of tryptophan when compared to many other common foods. Post-Thanksgiving dinner sleepiness is more likely related to other factors, such as the volume of food or the quantity of alcohol or simple carbohydrates consumed.
See how the amount of tryptophan in turkey stacks up against some other foods, according to the U.S. Department of Agriculture (USDA). The USDA nutrient lists also show that tryptophan amounts for certain foods can vary depending on how they’re prepared or cooked.
|Food||Amount of tryptophan in 100 grams (g) of food|
|dried spirulina||0.93 g|
|cheddar cheese||0.55 g|
|hard Parmesan cheese||0.48 g|
|broiled pork tenderloin||0.38–0.39 g|
|roasted whole turkey, with skin||0.29 g|
|turkey breast luncheon meat, low salt||0.19 g|
|hard-boiled eggs||0.15 g|
According to the National Academy of Sciences, the recommended dietary allowance (RDA) of tryptophan per day for an adult is 5 milligrams (mg) per 1 kilogram (kg) of body weight. For an adult weighing 150 pounds (68 kg), that translates to about 340 mg (or 0.34 g) per day.
Cherries affect melatonin levels, carbohydrates cause a spike and subsequent fall in blood sugar, and the minerals in bananas relax your muscles. In fact, many foods can impact energy levels in different ways. Any one of these factors could leave you sleepy.
It’s no surprise that not getting enough quality sleep can affect how you feel after a meal, too. If you’re relaxed and full, your body may feel more like resting, especially if you didn’t get enough sleep the night before.
Though they also recommend avoiding midday naps if you have trouble getting a good night’s sleep, at least one study found a post-lunch nap to improve alertness and both mental and physical performance.
Beyond helping you sleep better at night, exercise can keep you alert during the day, minimizing the risk of a post-meal slump. Multiple studies have found that regular exercise helps increase energy and reduce fatigue.
In other words, being sedentary doesn’t create some sort of energy reserve that you can tap into at will. Instead, being active helps ensure that you have the energy to push through your days.
On rare occasions, being tired after a meal or simply sleepy all the time could be a sign of another health problem. Conditions that can make post-meal drowsiness worse include:
If you’re frequently tired and have one of these conditions, talk to your doctor about possible solutions. If you’re unaware of an underlying medical condition but have other symptoms in addition to post-meal sleepiness, your doctor can help you identify what’s causing the slump.
Hyperglycemia (high blood sugar) may occur when too many sugars are consumed. It’s made worse if there’s inefficient or insufficient insulin to transport sugars to the cells for energy.
Sugars are the cells’ main source of energy, which explains why inefficient or insufficient insulin may leave you feeling tired. Other symptoms associated with hyperglycemia may include increased urination and thirst.
Hypoglycemia (low blood sugar) may occur due to consuming simple carbohydrates that are quickly digestible. These carbohydrates can make blood sugar levels spike and then crash in a short amount of time.
Hypoglycemia can also occur in someone with diabetes who has taken more insulin or other diabetes-specific medication than needed based on the foods they consumed. Sleepiness can be one primary symptom of hypoglycemia, along with:
Both hyperglycemia and hypoglycemia are serious medical conditions, especially for people with diabetes. They should be treated immediately as directed by your doctor.
Food intolerance or food allergies
An intolerance of or an allergy to certain foods can be another cause of post-meal tiredness. Food intolerances and allergies can impact digestion or other bodily functions.
If you find you’re feeling tired after meals, consider keeping a food diary. It can be a simple and helpful way to start identifying whether there are particular foods and ingredients, or other triggers, that may be having an impact on your energy levels.
A food diary, even if you only keep one for a few weeks, should include a record of everything you eat and drink. You should detail when you consume a food or beverage as well as how much. Also take notes on how you feel. Pay attention to your:
- energy levels
- sleep quality
- gastrointestinal activity
Write down any and all other symptoms. You may be able to draw some connections between your diet and how you feel, either on your own or with the help of a healthcare professional.
It’s always a good idea to discuss your diet with your healthcare provider, especially if you often feel tired after meals. Different diagnostic tests are available to help them find the root cause of your fatigue, including:
- the glucose tolerance test
- the hemoglobin A1C test
- the blood glucose test, either fasting or random
- blood or skin tests to look for food allergies or sensitivities
They may also suggest an elimination diet.
Your healthcare provider can determine whether or not testing is necessary for a diagnosis and, if so, what tests are most appropriate.
Regularly feeling tired after eating is something to discuss with your doctor. However, if the possibility of a more serious underlying condition has been ruled out or the fatigue only sets in occasionally, there are simple steps you can take to help maintain optimal energy levels.
Dietary and lifestyle habits that may help boost or sustain energy levels and counteract drowsiness include:
- drinking water to stay properly hydrated
- consuming appropriate electrolytes
- reducing the amount of food eaten at a single meal
- getting enough quality sleep
- exercising regularly
- limiting or avoiding alcohol
- modulating caffeine consumption
- eating foods that are good for your gut, blood sugar, insulin levels, and brain — including complex, high-fiber carbohydrates and healthy fats
Avoiding too much sugar and eating smaller, more frequent meals can also help.
If you feel tired after a meal, there’s a good chance it’s just your body responding to all of the biochemical changes caused by digestion. In other words, it’s completely normal.
However, if the symptom is disruptive or changing your lifestyle habits doesn’t seem to help, it might not hurt to talk to your doctor or to seek help from a dietitian.