I find myself not thinking every thought, but instead the same thoughts, over and over, in the same sequence. I think Dickens captured it well:

Scrooge went to bed again, and thought, and thought, and thought it over and over, and could make nothing of it. The more he thought, the more perplexed he was; and, the more he endeavoured not to think, the more he thought.

Marley’s Ghost bothered him exceedingly. Every time he resolved within himself, after mature inquiry, that it was all a dream, his mind flew back again, like a strong spring released, to its first position, and ​presented the same problem to be worked all through, ‘Was it a dream or not?’