Postprandial somnolence aka food coma and how to counteract it
Postprandial somnolence, which many describe colloquially as a food coma, refers to the sense of fatigue, sleepiness, or decreased energy levels that can occur shortly after eating a meal. Postprandial means after eating, while somnolence means sleepiness.
People with postprandial somnolence may experience the following symptoms after eating:
- drowsiness or sleepiness
- low energy levels
- lack of focus or concentration
Possible explanations
In response to the arrival of food in the stomach and small intestine, the activity of the parasympathetic nervous system increases and the activity of the sympathetic nervous system decreases. This shift in the balance of autonomic tone towards the parasympathetic system results in
a subjective state of low energy and a desire to be at rest, the opposite of the fight-or-flight state induced by high sympathetic tone. The larger the meal, the greater the shift in autonomic tone towards the parasympathetic system, regardless of the composition of the meal.
During the increase of the insulin after meals the uptake of tryptophan by the brain increases. In the brain, tryptophan is converted to serotonin, which is then converted to melatonin. Increased brain serotonin and melatonin levels result in sleepiness.
Insulin can also cause postprandial somnolence via another mechanism. Insulin increases the movement of potassium into cells from the extracellular fluid. The large movement of potassium from the extracellular fluid can lead to a mild hypokalemic state. The effects of hypokalemia can include fatigue, muscle weakness.
Cytokines are somnogenic and are likely key mediators of sleep responses to infection and food. Some proinflammatory cytokines correlate with daytime sleepiness
When people overeat, their bodies have the tendency to chemically change, including metabolic shifts. Postprandial alkaline tide, which is an increase in bicarbonate in the stomach — occur after each meal.
Mild cases of metabolic alkalosis cause no symptoms. However a typical manifestations of moderate to severe metabolic alkalosis include abnormal sensations, neuromuscular irritability, tetany, abnormal heart rhythms (usually due to accompanying electrolyte abnormalities such as low levels of potassium in the blood), coma, seizures, and temporary waxing and waning confusion.
Myths about the causes of post-prandial somnolence
Myth 1: Cerebral blood flow and oxygen delivery decreases after meals.
Although the passage of food into the gastrointestinal tract results in increased blood flow to the stomach and intestines, this is achieved by diversion of blood primarily from skeletal muscle tissue and by increasing the volume of blood pumped forward by the heart each minute. The flow of oxygen and blood to the brain is extremely tightly regulated by the circulatory system and does not drop after a meal.
Myth 2: Tryptophan from the turkey causes sleepiness Thanksgiving
A common myth holds that turkey is especially high in tryptophan, resulting in sleepiness after it is consumed, as may occur at the traditional meal of the North American holiday of Thanksgiving. However, the tryptophan content of turkey is comparable to chicken, beef, and other meats, and does not result in higher blood tryptophan levels than other common foods.
Counteraction of the postprandial somnolence
A 2015 study, reported in the journal Ergonomics, showed that, for twenty healthy subjects, exposure to blue-enriched light during the post-lunch dip period significantly reduced the EEG alpha activity, and increased task performance.
Dr Moira Junge, psychologist and spokesperson for the Sleep Health Foundation, posits that all human beings will experience the post-lunch dip regardless of whether they’ve eaten lunch. However, if you do eat lunch, the nutritional content of the meal you consume could accentuate your natural desire to siesta. In this context Junge favours the practice of postprandial siesta.
Takeaways
Postprandial somnolence, which many describe colloquially as a food coma, refers to the sense of fatigue, sleepiness, or decreased energy levels that can occur shortly after eating a meal.
Exposure to blue-enriched light during the post-lunch dip period significantly can increase task performance
Siesta is a healthy habit after the lunch meal. For more information about the siesta consider reading the following article: https://medium.com/@dr.victor.bodo/recharge-your-batteries-with-siestas-and-power-naps-c40970299b7d
