There are various items of the etiology and pathogenesis of insomnia in TCM theory,in which over-thinking,depression,sadness,anger,panic and so on are considered as the key emotional factors to the occurrence of insomnia. As a main and common symptom of depression syndrome,dysfunctions of heart,spleen,liver and gallbladder play important role in the pathogenesis of insomnia.This paper divided the classifications of emotions into “the external emotional factors” and “the internal emotional factors”.The former refers to irritable emotional changes caused by negative events. When inner peace is retrieved,insomnia is almost cured. The latter refers to psychological characteristics of depression syndrome,personality traits and Qi-stagnation constitution of the individual.The one who has “the internal emotional factors” always shows susceptibility and irritability to those external emotional stimulations,and can behaves depression,sadness,anger,panic and refractory insomnia. In most cases,good night sleep relieves depression,while the disappearance of depression syndrome promotes better sleep. So in the treatment of insomnia due to depression syndrome,soothing the liver and relieving depression could tranquilize mind and promot sleep,and vice versa. Relieving depression and promoting sleep interact on each other.