The Diagnostic and Statistical Manual of Mental Disorders (DSM-V) is the worldwide mostly used tool to diagnose mental health problems. According to this manual, there are 9 core features of depression. Each one of them people can experience sometimes, according to circumstances, and it would be considered a “normal” reaction; only the accumulation of these symptoms counts. You need to experience at least 5 features over a period of 2 weeks, which will as such impair your self care, social or occupational functioning. The symptoms are: depressed mood most of the day, nearly every day, feeling sad, empty or hopeless; loss of interest or pleasure in previously enjoyable activities; significant weight loss or weight gain; sleeping problems; restlessness or being slowed down in movement; fatigue or loss of energy; feelings of worthlessness or guilt; diminished ability to think or concentrate, or indecisiveness; recurrent thoughts of death, contemplating of suicide, or suicide attempt.
If you meet more then 5 symptoms of depression, please consult a doctor or mental health professional.