Chinese medicine believes that the period of the day from 1 a.m. to 3 a.m is the best time for liver repair, and the purification and renewal of old turbid blood is completed from 1 a.m. to 3 a.m. If the rest is not good and the liver cannot be repaired, it is easy to cause problems such as irritability, rough skin, the facial color schungite, dark spots and so on.
In addition, falling asleep in the middle of the night will help the liver and gallbladder to be smooth . During the day, people will have a clear mind and a rosy complexion. In modern society,and high incidence of liver cancer ,fatty liver, cirrhosis . In addition to eating habits and workplace stress, staying up late is also an important pathogenic factor.
中医认为，丑时是肝脏修复的最佳时段，旧浊血液的净化更新在肝经当令时完成.若休息不好，肝脏不得修复则易引发情绪烦躁、皮肤粗糙、面色青灰、黑斑等问题。
此外，在半夜睡熟有助于肝胆之气舒畅条达，白天人会头脑清晰，气色红润。现代社会脂肪肝、肝硬化、肝癌多发，除饮食习惯和职场压力外，熬夜也是很重要的致病因素。
来源：黄帝内经
