"Before I knew anything about bipolar disorder - much less than I myself had it - I called this sensation "racy brain." Thoughts and music would be zooming through my head so fast that sometimes I wanted to scream. If it was going on at bedtime, it could take me an hour or more of concentrating on word games to get myself to sleep.
Racing thoughts are not just "thinking fast." They are thoughts that just won't be quiet; they can be in the background of other thoughts or take over your consciousness; they can gallop around in the sufferer's head like a carousel gone out of control.
Components of racing thoughts can include music, snatches of conversation from movies or television or books, one's own voice or other voices repeating a phrase or sentences again and again, or even rhythms of pressure without any "sound" in the thought.
Racing thoughts is distinct from "hearing voices," which is a symptom of schizophrenia, severe mania or schizoaffective disorder.
Racing thoughts can be a symptom of mania, a mixed episode, depression or an anxiety disorder. Sometimes it is accompanied by a pounding heart or pounding pulses, including drumming in the ears. "
~ Marcia Purse