Depression - Symptoms of Major Depression Having at least five of these symptoms occurring nearly every day for at least two weeks: Feeling sad or empty Decreased interest or pleasure in activities Appetite change with weight loss or weight gain Decreased or increased sleeping Fatigue or loss of energy Feeling worthless or guilty Being either agitated or slowed down Difficulty thinking or concentrating Recurrent thoughts of death or suicide Other Types of Depression Bipolar disorder (previously called manic-depressive disorder) — occurrence of episodes of major depression and episodes of abnormally elevated mood called mania (severe) or hypomania (less severe) Dysthymia — mild depression symptoms lasting for at least two years Postpartum depression — a mother's depression occurring after the birth of her baby Seasonal affective disorder — major depression occurring regularly in seasons with low sunlight