You’ve just finished a large lunch. Waves of sleepiness sweep over you, and you have absolutely no motivation to go back to work. Does this happen to you? If so, you may be experiencing postprandial somnolence, a common condition often referred to as a “food coma”. What is a food coma – and what causes it?
What is a Food Coma?
A food coma, or postprandial somnolence, refers to the low energy state that people experience after eating a large meal. Some people have it to such a degree that they have to drink several cups of coffee with a meal to stay awake and get back to work.
What Causes a Food Coma: Nerves Play a Role
There are two explanations for food comas or postprandial somnolence. One has to do with the way the nervous system responds to a meal, and the other has to do with the effects of insulin.
When you eat a meal, particularly a large one, it turns on the portion of the nervous system called the parasympathetic nervous system. When the parasympathetic sympathetic system comes into play, it slows things down so your food can be digested more easily. This division of the nervous system is sometimes dubbed the “rest and digest” portion, which is exactly what the parasympathetic nervous system is geared towards.
The other main component of the nervous system, called the sympathetic system, sends nerve impulses to the heart to speed it up and to the muscles to gear you up to move more quickly. It’s often referred to as the “fight or flight” portion of the nervous system.
Usually there’s a balance between the two, but when you eat a meal the parasympathetic nervous system is preferentially activated to help digest your food, which, unfortunately, make you sleepy and unmotivated.
Insulin Plays a Role Too
After a meal, particularly one high in carbohydrates, insulin levels go up. This causes amino acids from the protein you’ve eaten to be taken up into cells. The one that isn’t taken up by cells is tryptophan. With the other amino acids out of the way, tryptophan can now more easily be transported into the brain. When trytophan enters the brain it alters levels of melatonin and other brain chemicals that cause drowsiness. If you eat a meal containing lots of trytophan, the effect will be even more pronounced.
How to Prevent a Food Coma
The best way to stave off a food coma is to reduce the amount of food you eat at a single sitting – and eat fewer high-glycemic carbs like white rice, white bread, and potatoes that cause insulin spikes.
It also helps to walk around after a meal rather than reclining in an easy chair. Exercise kicks the sympathetic nervous system into gear, which helps to restore your energy and motivation. Whatever you do, don’t drink alcohol with a meal if you’re prone to postprandial somnolence, it’ll only make things worse.
What is a Food Coma: The Bottom Line?
Postprandial somnolence can destroy your productivity, if you let it. Take steps to change your eating style if you’re prone towards food comas after a meal.
American Journal of Clinical Nutrition. 77(1): 128-32.
Merck Manual. Eighteenth edition. 2006.