Our understanding of depressive disorders has evolved with time. Hippocrates referred to the condition as melancholia. Freud considered the condition a consequence of guilt and conflicting emotions. The 1950s saw the condition being divided into endogenous and neurotic depression.Today there is consensus that depression is a syndrome often characterized by more than one symptom. Intense sadness and irritability for either short or long durations manifest during episodes of the condition. Physical signs include lethargy, body aches, mood swings, lack of appetite, overeating, and poor sleep patterns.