The symptoms of bipolar disorder depend upon whether the sufferer is experiencing a depressive or manic episode. A person must have experienced at least one manic episode to be diagnosed with bipolar disorder. Symptoms and signs of manic episodes include elevated or expansive mood, rushed or pressured speech, racing thoughts, decreased need for sleep, poor judgment, increased goal-directed activity, impulsivity, grandiose thoughts (thinking one has superpowers or special abilities), and tangential speech (switching topics frequently). Major depressive episodes often alternate with manic episodes in bipolar disorder. These episodes can be characterized by feelings of hopelessness, depressed mood, decreased interest in pleasurable activities, changes in appetite, sleep disturbances or changes in sleep patterns, fatigue, and trouble concentrating. Suicidal thoughts can also accompany the symptoms of depression.