It would be nice to have a version of the Beaufort scale or Richter scale for information. The Beaufort scale is the one for wind, that starts with '0. Calm. Smoke rises vertically' and ends with '12. Hurricane. Considerable and widespread damage to structures'.
So I've had a go.
0. Calm. Ideas rise vertically from page to mind.
1. Light difficulty. Slower reading. Dictionary pages rustle.
2. Moderate difficulty. Reader lightly swaying; visible perplexity.
3. Difficulty. Head shaking, audible groaning.
4. Severe difficulty. Loud muttering, and music heard from helpline queue.
5. Very severe complexity. Foaming. Abrupt movement about room, with swearing.
6. Storm. Whole documents in motion, from table to floor.
7. Brainstorm. Considerable damage to conceptual structures.
8. Typhoo. Reader flattened in darkened room, with cup of hot sweet tea.