Complex sentence: He also asserted that his motivation for breaking the world sleep deprivation record was neither fame nor fortune, but that his intention was to promote his radical theories of human neurological degeneration that were proposed in his self-published book, "Left In The Dark".
Split into simpler sentences: He also asserted that his motivation for breaking the world sleep deprivation record was neither fame nor fortune. But that his intention was to promote his radical theories of human neurological degeneration that were proposed in his self-published book, "Left In The Dark".