Depression is more than just occasionally having the blues. Depression is a mood disorder. You feel sad and have no joy in life. You may feel that you have nothing to live for.
Bipolar disorder involves periods of excitability (mania) alternating with periods of depression. The "mood swings" between mania and depression can be very abrupt.
Adolescent depression is a disorder that occurs during the teenage years, and involves persistent sadness, discouragement, loss of self-worth, and loss of interest in usual activities.
Major depression is when a person has five or more symptoms of depression for at least 2 weeks. These symptoms include feeling sad, hopeless, worthless, or pessimistic.
Mania is an abnormally elated mental state, typically characterized by feelings of euphoria, lack of inhibitions, racing thoughts, diminished need for sleep, talkativeness, risk taking, and irritab...