Major depression can range from mild to severe depending on the extent of the symptoms.
In some cases, depression can be so severe that people develop delusions and hallucinations. Many scientists believe that psychotic depression is not just a severe variety of major depression, but in fact a distinct disorder. The second most common form of depression is dysthymia . Dysthymia can be thought of as a low grade form of depression that lasts two years or more. As with a low grade fever, you feel awful, but you can get out of bed if you have to.