Bipolar disorder — sometimes called manic-depressive disorder — is associated with mood swings that range from the lows of depression to the highs of mania. When you become depressed, you may feel sad or hopeless and lose interest or pleasure in most activities. When one's mood shifts in the other direction, he/she may feel euphoric and full of energy. Mood shifts may occur only a few times a year, or as often as several times a day. In some cases, bipolar disorder causes symptoms of depression and mania at the same time.
Although bipolar disorder is a disruptive, long-term condition, an individual can keep your moods in check by following a treatment plan. In most cases, bipolar disorder can be controlled with medications and psychological counseling (psychotherapy).
Source: www.mayclinic.org