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‘Food coma’ sounds dramatic, but it refers to postprandial somnolence — the drowsiness that follows a meal. Researchers haven’t studied it extensively in humans, but experiments have been done on rodents, fruit flies, and nematodes.
Rising Glucose Levels Contribute to Afternoon Sleepiness
High-carb, sugary foods — potatoes, breakfast cereals, and white bread — are more likely to trigger drowsiness and an energy slump. They have a high glycemic index and release glucose rapidly into the bloodstream.
When blood glucose rises, the body releases insulin. Insulin helps muscle and fat cells absorb glucose, which can cause blood sugar to dip and energy to fall.
After eating, the parasympathetic nervous system kicks in and shifts the body into ‘rest and digest’ mode, the opposite of the sympathetic ‘fight or flight’ response.
How sleepy this makes you depends on how much you eat in one sitting. The more you eat, the longer your body will need to digest the meal.
Tryptophan Also Plays a Role in Post-Meal Drowsiness
The amino acid tryptophan can also contribute to post-meal drowsiness. It appears in many protein-rich foods, including eggs, fish, and meat.
Insulin drives many amino acids into muscle cells but not tryptophan. That leaves tryptophan free to cross into the brain, where it’s converted into serotonin and melatonin — chemicals that promote relaxation and sleep.
A ScienceFocus guide recommends avoiding high-carbohydrate meals like sandwiches or large servings of rice. Instead, include protein, healthy fats, and vegetables to balance your plate. Avoid overeating in one sitting.
