Everyone has experienced it: that feeling of exhaustion and sleepiness after eating a meal. Whether it’s after Thanksgiving dinner, or just a regular meal, that post-meal tiredness has affected all of us at one time or another. Have you ever asked yourself why eating a meal is often followed by drowsiness, and the desire to rest?
Feeling a bit tired after a meal is completely normal, and it is generally not something you should be concerned about. Several factors contribute to the post-meal food coma, or in medical speak, postprandial somnolence. If you’d like to minimize the drowsy effects of post-meal sleepiness, there are some steps you can take, and the first step is taking some time to understand digestion.
Simply living and existing is energy-intensive. Whether you are constantly working out and exercising, or living a sedentary lifestyle, we all need energy to live. How do we get this energy? From food, of course.
Digestion is the biggest factor contributing to the tiredness felt after eating a meal. After all, your digestive system has a lot of work to do, especially after you eat a big meal. Knowing how digestion works will help you understand what is really going on after you finish a meal.
After you finish a meal, it takes about six to eight hours for food to pass through your stomach and small intestines. During this time, the digestive system breaks food down into glucose, which our bodies use as fuel. Macronutrients, like proteins, provide energy to our body through calories. In addition to our digestive cycles providing fuel and energy to our bodies, the digestive cycle triggers a number of other responses in our bodies.
To create the feeling of fullness, our bodies release hormones like amylin, glucagon, cholecystokinin (CCK). Also, as we digest, our blood sugar rises, and in response, insulin is produced. Insulin allows the sugar in our blood to be taken up by our cells to be used as energy.
All of these digestive processes are carried out by the parasympathetic nervous system. The parasympathetic nervous system is involuntary, meaning that it operates without you knowing it. It is responsible for both sleep and digestion, which is why it is sometimes referred to as the “rest and digest” function.
While digesting, our parasympathetic nervous systems assume we are in a state of rest. During digestion, more blood is sent to the digestive system. Normally, the digestive system receives about 20%-25% of our blood pumped from the heart; however, during digestion, the amount of blood flow sent to the system can almost double.
It is no wonder why digestion is so important: it provides our bodies with the fuel and energy we need to live. And, digestion is no easy task. After we eat a meal, our digestive system is hard at work, turning that food into fuel and energy, releasing our hormones, regulating chemicals in the blood and cells (like sugar), and pushing that food onwards to the GI tract.
So we’ve discussed how the digestive cycle works, and why it’s important. Now we can get into specific reasons that this process may make us feel tired.
Eating foods that cause your blood sugar to drop can help reinforce the tired feeling after eating. After you eat a meal, food is broken down into glucose (sugar), and transported to the blood where it can then be distributed to cells with insulin. Eating some foods, like carbohydrates, increase your blood sugar rapidly, and then quickly drops off, leaving you feeling tired.
The circadian rhythm is a 24-hour internal process that regulates the sleep and wake cycle. It is also thought of as the body's internal clock. Studies show that eating may affect the circadian rhythm because “human molecular clocks may be regulated by feeding time and could underpin plasma glucose changes”. In other words, meal timing is very important, because eating at different times of the day can adjust the circadian rhythms of individual cells and tissues, leading to tiredness.
Additionally, humans typically get drowsy around 2-3 pm, usually after eating lunch. This is a natural part of our circadian rhythm that corresponds with alertness, sleepiness, and attention span.
If you are not rested, the tiredness that follows after eating a meal may increase. After you eat, you are more likely to feel full and rested, and if you did not get quality sleep recently, then you are more likely to feel tired after eating a meal. Therefore, if you got a poor night’s sleep before eating a meal, you may be even more tired after eating.
Sleep disorders are another reason that may be causing you to feel extra tired after eating. These can include:
If you are affected by any of these sleep disorders, it could seriously be affecting your quality of sleep, how much sleep you get, and therefore your daytime alertness and energy. If you are affected by any of these sleep disorders, that may be a powerful contributing factor, resulting in your chronic post-meal fatigue.
Drinking alcohol during a meal can make you feel significantly more tired. Alcohol is a nervous system depressant, meaning that it has a sedative effect, making you relaxed and drowsy. Furthermore, drinking alcohol negatively impacts your quality of sleep.
Eating large amounts of food may worsen sleepiness after a meal. For example, you are more likely to feel tired in the afternoon if you have a large lunch. Eating causes our blood sugar to rise and then drop, resulting in tiredness, so if you eat more, your blood sugar may rise more to accommodate the amount of food consumed, and therefore there will be a larger drop. Additionally, larger meals are more work for your digestive system to handle, and require more blood and energy to process.
Although the digestive system processes all food in the same manner, different foods can affect your body in different ways, due to the varying composition of many foods.
One commonly cited example of certain foods making you sleepy is turkey. Turkey contains a chemical called L-tryptophan, one of nine essential amino acids. When tryptophan crosses the blood-brain barrier, it stimulates the production of serotonin and melatonin. Melatonin is known as the “sleep chemical”. It is an important factor in the Circadian Rhythm and sleep. Serotonin is a neurotransmitter that helps to regulate sleep. So, it is no wonder that tryptophan is connected to after eating a large amount of turkey, because of its connection to melatonin and serotonin, two sleep-related chemicals.
In the United States, Thanksgiving dinner is commonly served with turkey being the main course. After eating the turkey-centric meal, people often feel this sudden tiredness and urge to sleep, sometimes contributing this feeling to a large amount of turkey they’ve eaten, and therefore tryptophan in the bloodstream. However, the idea that tryptophan directly leads to this sensation is mostly a myth.
Tryptophan cannot freely circulate in the brain, because it is unable to pass the blood-brain barrier on its own, instead, it has to enter by hitching onto a transport protein to enter the brain. Other amino acids use the same tactic to break through the blood-brain barrier, and there are many of them that are competing to get access into the brain. Therefore, very little tryptophan is able to get into the brain, where it can produce melatonin and serotonin. However, it is important to note that tryptophan can be stored in the body, and released when you eat carbohydrates.
The reason you feel sleepy after a Thanksgiving meal is likely due to other factors. For example, as we discussed above, the quantity of food eaten is a factor, along with the consumption of alcohol and carbohydrates.
Carbohydrates are also a factor in your diet that may be causing the sleepy feeling after eating a meal. As we discussed above, sudden drops in blood sugar can trigger drowsiness, and eating carbohydrates does just that: they cause a sudden spike in blood sugar, followed by a quick drop.
There are many other foods that may cause you to feel sleepy after a meal. For example, cherries affect levels of melatonin, bananas help your muscles relax, and like carbohydrates, foods high in protein may contribute to sleepiness as well.
Regular activity and exercise help to boost energy and reduce fatigue. Exercise may help to increase your levels of energy, and reduce the effects of post-meal fatigue. On the other hand, being sedentary reduces your overall energy (and stores of energy), resulting in increased exhaustion and tiredness after meals.
Food allergies may be contributing to the problem, too. Any foods that you are allergic or sensitive/intolerant to can contribute to fatigue after eating them. When you are allergic to a food, and consume it, your body releases histamines, causing daytime sleepiness. Food sensitivities and allergies can cause physical exhaustion, mental fatigue, and/or an upset stomach.
Seasonal allergies can contribute to daytime sleepiness and chronic fatigue just as food allergies do. Like food allergies, seasonal allergies release histamines in the body when you are exposed to the allergen, leaving you feeling mentally and/or physically tired.
Several health conditions can play a factor in feeling tired after eating.
Diabetes. Diabetes is a common reason for feeling tired after a meal. Diabetes affects your body's ability to produce insulin, which allows for the transfer of energy (sugar) from your blood to cells. When someone is affected with diabetes, their ability to produce insulin is very low or non-existent, resulting in fatigue. This is because the energy your body needs to function is unable to be transferred to the cells that need it to function.
Underactive thyroid. When you have an underactive thyroid, or hypothyroidism,your thyroid is unable to produce enough thyroid hormones. The thyroid is responsible for delivering energy to the organs in the body, and also helps the heartbeat and the digestive system work. Therefore, it is no surprise that a common symptom of hypothyroidism is fatigue.
Celiacs disease. Celiac disease damages the villi in the small intestine that help you to absorb vitamins, minerals, and nutrients. Celiac disease leaves those affected by it chronically fatigued (along with other symptoms) when they consume barley, wheat, and rye, which they are unable to digest.
Anemia. Anemia is a common cause of fatigue for many people around the world. Anemia is a condition where you do not have enough red blood cells, resulting in chronic fatigue.
Mental conditions may also contribute to chronic drowsiness after eating. Depression and anxiety are two very common mental disorders that can leave those affected by them feeling chronically tired.
Improving your sleep environment includes making sure you are sleeping in a cool environment, so you don’t overheat, along with reducing any noise that may keep you up at night. One great way to remedy a noisy sleep environment is by playing ambient music, or white noise, while you sleep.
Another effective way to improve your sleep environment is making sure you have the right mattress. Sleeping in a mattress that doesn’t fit your needs can leave you with day-time fatigue and an inability to get the rest you need. If you think you need to get a new mattress, check out Latex For Less for affordable and comfortable latex mattresses.
Having a slight dip in energy after eating a meal is natural. However, being chronically fatigued or tired after eating a meal may signal another problem. If you have any of these problems listed below, you should consult your healthcare professional: