I am in my 10 th year with very bad tinnitus. I learned how to sleep even with very loud tinnitus. How do i fall asleep? I don't know. Although i hear very loud tinnitus, my brain is so used to hearing that, that it falls asleep when some conditions are met (me in bed, with the intention to fall asleep).
That does not mean that tinnitus is not a huge problem for the sufferer. It means that the innate power of adaptation of an organism is so big that, if it has no choice, an organism adapts itself to hellish life conditions.