There are twelve hours in a day, and the human body has twelve meridians, and each hour corresponds to one meridian. Qi and blood flow for a week every day, starting from the lung meridian that is full of yin and ending with the liver meridian that is full of ugliness, and so on. This rule was called "Meridian Flow" by the ancients to guide treatment and health preservation.

The later time of the day (from 1 p.m. to 3: 00 p.m.) corresponds to the last month of summer in a year (light summer and heavy summer). At the end of the day, it is also called sundial and sundial, because at this time, the sun begins to set in the west.

At the end of the day, the blood in the small intestine is at its peak. The small intestine is connected with the stomach on the upper side and the large intestine on the lower side. The main task is to separate turbid Shui Gu after gastric emptying. Clear body fluids are absorbed by the small intestinal wall and then transported to the whole body. Finally, excess water seeps into the bladder, and turbid dregs enter the large intestine.

From the health point of view, we'd better finish lunch at noon and then absorb nutrition when the small intestine is at its peak. If we eat lunch too late, there will be almost no time until the decomposed lunch reaches the small intestine, and insufficient digestion and absorption will easily form phlegm and dampness in the body.

Although the untimely yang is still abundant, the weak yin is gradually emerging, and the qi of heaven, earth and human body has changed from outward extension to inward folding, so it is advisable to have a rest during this period instead of strenuous exercise.