While these are common symptoms of depression, they may also occur in patterns. For example, a person may experience depression with mania or hypomania -- a condition sometimes calledmanic depression or bipolar disorder. Or the symptoms may be seasonal as in the case of seasonal affective disorder.
There are several types of manic depression. People with bipolar II disorder have at least one episode of major depression and at least one hypomanic -- mild elation or high -- episode. People with bipolar I disorder have a history of at least one manic -- extreme elation or high -- episode, with or without past major depressive episodes. A patient with unipolar depression has major depression only and has never had a full hypomanic or manic episode. A new category, though, in the DSM-5 allows for the presence of some symptoms of mania or hypomania during a full depressive episode in someone who technically hasn't met the full criteria for bipolar disorder. That suggests the line between unipolar and bipolar disorder can sometimes be blurry.