Funnily enough, I have mild tinnitus, but sleep very soundly. I have a fan on 24/7 in my bedroom that helps enough for drowning out the tinnitus sound. I rarely if ever wake up in the middle of the night, and wake up fairly refreshed. I even fall asleep relatively fast compared to some other people I know.

Elsewhere in this thread, it's been mentioned that there are several types of tinnitus (it's apparently an umbrella term), and some tinnitus can be caused by a firm pillow and bruxism, which fits my description.

I wonder if the type of tinnitus has more or less effect on sleep than others.