A food coma is a slang term for the physiological phenomenon scientifically called postprandial somnolence. A food coma is not really a coma, nor is it related in any way. A food coma is a state of drowsiness or lethargy following a big meal. It is marked by deep, rhythmic breathing, loss of energy, drowsiness, and hazy thinking.
The reason people go into a food coma after large meals is due to the response of the autonomic nervous system to the presence of food. After large meals, more control of the body is diverted to the parasympathetic nervous system from the sympathetic nervous system. The parasympathetic nervous system is automatic. It takes no thought to activate. Since the sympathetic nervous system controls most of our muscles for movement, this diversion gives us a feeling of having diminished energy and makes us want to relax or sleep. The more food eaten at once, the more control is shifted, and the more the effects are felt.
At the same time, glucose from the food causes insulin levels to rise. Insulin causes tryptophan to become available to the brain. When tryptophan gets to the brain, it is converted to serotonin. The serotonin is then converted to melatonin, which results in sleepiness.
Another factor at work in producing postprandial somnolence is respiratory acidosis. Food causes the stomach to be acidic. Some of the acid comes from the blood, turning it slightly basic. When the blood is basic, not as much oxygen gets to the cells of the body. This causes us to breathe slowly and deeply. This result of respiratory acidosis also causes drowsiness.
Posted 1138 day ago