The sometimes inexplicable sadness may clinically belong to depressive mood. This symptom that sometimes occurs is more likely to be a depressive mood because it is not long-term and consistent. In case of inexplicable sadness, you need to ask yourself: what came to your mind internally at that time, including words, pictures or related experiences. At this time to analyze the content, cognitive-behavioral theory believes that the generation of sadness is mainly due to unreasonable evaluation of the scene at the time, and unreasonable evaluation is the root cause of the sadness, so the analysis of the idea is very important, including the analysis of the idea of supporting evidence, or not supporting evidence, for the idea of change, etc. do experience, and ultimately achieve the purpose of treating sadness. If this sadness has affected work, study, life, accompanied by depressed mood, slow thinking or lack of interest in fun, can not experience pleasure, self-injury, suicidal thoughts and behavior, more consider the possibility of depression, should apply antidepressants for systematic standardized treatment. In particular, the application of 5-hydroxytryptamine reuptake inhibitor drugs, such as paroxetine and sertraline, can achieve good therapeutic results.