Clinical depression is a medical condition with a biological basis that goes beyond mere sadness. Key symptoms are a sad, empty or irritable mood and a loss of interest or pleasure. It may include feelings of being exhausted and unmotivated. The condition interferes with a person's daily activities. It is the most common psychiatric condition. Types of depressive disorders include major depressive disorder and persistent depressive disorder. The former has an episodic course, and the latter a chronic, persistent course.
Depression may arise in the peripartum period, which refers to during pregnancy or the first four weeks following delivery. Depression may also be precipitated by loss, grief and bereavement. Bereavement is a severe stressor and may impact both mental and physical health as well as interpersonal and occupational functioning. Although bereavement may induce great suffering, it does not always lead to depression. Bereavement-related depression tends to occur in persons with other vulnerabilities to depressive disorders, such as a personal or family history of depression.