Drowsiness after eating may be a normal physiological phenomenon, or it may be caused by postprandial hypotension and other factors. 1. Normal physiological phenomenon: After eating, the gastrointestinal tract begins to digest food. This process requires the participation of a large amount of blood, and therefore may lead to a relative lack of blood supply to the brain. When the blood supply to the brain is insufficient, some uncomfortable symptoms, such as sleepiness, drowsiness, yawning and so on, will appear. 2. Postprandial hypotension: If an older person is sleepy after eating a meal, the possibility of postprandial hypotension should be considered. Postprandial hypotension sometimes leads to fatigue, dizziness, and even fainting. In order to accurately determine this situation, it is necessary to strictly measure the blood pressure before and after meals. After excluding physiological phenomena from sleepiness after eating, you should go to the hospital in time to make a clear diagnosis and take effective measures under the guidance of specialized doctors.