Everyone has depressed mood. Depressed mood manifests itself as unhappiness, which is often related to things in life, such as failure in exams, failure in graduate school, criticism by leaders, and sudden emergencies at home. This unhappiness is different from the unhappiness of depression, which manifests as a bad mood for up to 2 weeks or more. In addition to the fact that things happen for a reason, the timing, depressed mood often returns to normal after a short period of self-adjustment, is also one of the differences from depression. Putting it all together, depression is a short period of unhappiness, but it often has a reason.