《伤寒论·辨脉法》
这是因为，中午为阳，半夜为阴，阳不和得阴就会调和，所以中午得病半夜就会解除；阴不和得阳也会调和，所以半夜得病，第二天中午可愈。
何以言之？日中得病，夜半愈者，以阳得阴则解也。夜半得病，明日日中愈者，以阴得阳则解也。
This is because noon belongs to yang and midnight belongs to yin. When yang and yin are not in harmony, yin will regulate it, so if one gets sick at noon, it will be resolved by midnight; when yin and yang are not in harmony, yang will regulate it, so if one gets sick at midnight, he or she can recover by noon the next day.