Depression may be described as feeling sad, blue, unhappy, miserable, or down in the dumps. Most of us feel this way at one time or another for short periods.True clinical depression is a mood disorder in which feelings of sadness, loss, anger, or frustration interfere with everyday life for weeks or longer.Depression, which doctors call major depressive disorder, isn’t something you can just “snap out of.” It is thought to be caused by an imbalance ...