It’s normal to experience a range of feelings and moods. Sometimes you feel incredibly excited and happy, while other times you feel sad, anxious or outright miserable. Bipolar disorder (sometimes called manic depression) is a mental health condition where people experience extreme highs, called mania, and intense periods of sadness or depression. These phases of mania and depression are called episodes, and can shift rapidly. Some people may experience both at the same time. Along with changes in mood, people experience other symptoms that affect their energy, sleep habits and behavior.