The causes of sleepiness after dinner: 1. Consider that after eating, the stomach needs more blood circulation to digest food, which will lead to insufficient blood circulation in the brain, and because the blood carries oxygen, the patient will have a lack of oxygen in the brain cells, and the patient can show yawning, sleepiness, and in severe cases, drowsiness. 2. Sleepiness after dinner can also be seen after the patient eats greasy food, which is more obvious. This is due to the fact that after eating greasy, the blood is in a high fat and viscous state, the blood flow is slowed down, resulting in the lack of oxygen to the brain cells, the patient can appear sleepy. 3, sleepy after dinner, can also be seen in some patients with diabetes, due to the disease of diabetes patients, high blood sugar, after eating, resulting in higher blood sugar, the state of high blood sugar will appear hypertonic reaction, the patient can appear sleepy after dinner. In serious cases it is necessary to sleep, it is recommended that such patients usually drink more water to maintain adequate blood volume.