《黄帝内经·素问·脉要精微论》
岐伯回答说：诊脉通常是以早晨太阳将要升起之前的时间为最好，此时人还没有劳于事，阴气未被扰动，阳气尚未耗散，饮食也未曾进过，经脉之气尚未充盛，络脉之气也很匀静，气血未受到扰乱，因而可以诊察出有病的脉象。
岐伯对曰：诊法常以平旦，阴气未动，阳气未散，饮食未进，经脉未盛，络脉调匀，气血未乱，故乃可诊有过之脉。
Qibo replied: Acupuncture usually requires the time when the sun has just risen in the morning to be most effective. At this time, people have not yet worked on business, yin energy has not been disturbed, yang energy has not yet been consumed, food has not been ingested, the energy of meridians has not yet become stimulated, and the energy of the connecting vessels is also very even. No disturbance has entered the blood and energy, which is why it is possible to find diseased pulse phenomena through acupuncture.