The normal activities of the human body involve the rising of yin and the descending of yang. If this regular pattern is disrupted, it is very difficult to correct.
Therefore, insomnia is a stubborn issue.
When treating it, this pathological phenomenon of yin-yang inversion should be reversed to restore the normal physiological state, which will improve sleep.
However, although insomnia has to do with the disconnection between the heart and the kidneys, it is also closely related to the liver, which stores blood.
The Inner Canon's chapter on the five organs states: "When people sleep, the blood returns to the liver," and Medical Introduction also mentions: "When people move, blood circulates through the meridians, and when still, blood returns to the liver."
Hence the saying, "If one cannot sleep at midnight, it is because the blood does not return to the liver," meaning that the inability to sleep at midnight is related to blood not returning to the liver.
