What tinnitus can involve
Tinnitus is sound with no external source: ringing, buzzing, hissing or humming that only you can hear. What varies is not usually whether it is there but how much room it takes up. Tiredness, stress, a quiet room or a bad night can each move it from background to foreground, and that shift is what makes concentration and sleep hard.
Because nobody else can hear it, the distress is easy to underplay and difficult to describe. Recording how loud it seemed and what it interfered with, day by day, turns something private into a record. It also shows the days it receded, which is worth knowing when it feels constant.