Bipolar I Disorder is one of the three major types of Bipolar Disorder. Bipolar I is characterized by one or more manic episodes or mixed episodes and one or more major depressive episodes. A mixed episode is when there are symptoms of mania and depression occurring almost everyday for at least one week. Manic symptoms (as described in a previous post) can be so severe that they require immediate hospital care. A depressive episode usually lasts two weeks.