Objectives : The aim of this paper is to examine the mechanisms of spontaneous sweating and night sweating, their relationship and how the explanations of their mechanisms have changed over the course of time, through examination of past discussions on spontaneous sweating and night sweating.
Methods : Contents in classical medical texts that mention the mechanisms of spontaneous sweating and night sweating among search results from databases such as the Siku Quanshu were analyzed, followed by examination of each of their mechanisms, and their relationship with each other.
Results & Conclusions : The cause of night sweating before the 『Danxixinfa』 was seen to be caused by yang deficiency in relation to problems of Exterior Qi and the theory of 'Heart governs perspiration', as the focus was on the phenomenon of sweating. However, it seems that yin deficiency came to be seen as playing a more fundamental role in the process of determining the root cause of night sweating. Moreover, Zhu Danxi's emphasis on nurturing yin, the composition of Dangguiliuhuangtang, and the development of the fire-heat pathology since the Jin Yuan period added to this shift in perspective. Night sweating from Shanghan could be seen as a sign of the already damaged Exterior Qi becoming more deficient while the pathogenic qi is in the half-exterior-half-interior zone, or as the pathogenic qi which entered with the Exterior Qi unsettling yin, or as a result of heat that is produced in the struggle between healthy qi and pathogenic qi that happens when Exterior Qi enters. Night sweating from miscellaneous disease could be seen as a sign of a deficient exterior that resulted from excessive entering of the Exterior Qi during yin deficiency, or resulting from relatively excessive Exterior Qi to deficient yin, producing heat that leads to sweating. If yin is not cultivated during the night but rather consumed leading to deficiency of Exterior Qi which also needs to be cultivated during night time, it could result in sweating.