As somebody with tinnitus, forgive me, this seemed instinctively obvious. A very bad night of sleep raises the volume of the tinnitus substantially. Stress does the same.

Not sure about stress, but definitely have the same exp re sleep. If I’m tired the ringing is very noticeable, when I wake up early after a late night it can be deafening. But besides from noticing it being “louder” it seems to go away, or I just ignore it.

It’s been well known for as long time, the news here is the specific biological mechanism, which may open up new areas of research.

as always, the devil (and research) is in the details

it seems that these researchers think it's non-REM sleep that helps in prevention, not just sleep in general

So perhaps the connection is sleep -> stress -> tinnitus?

Also, in the fleeting moments between waking and full consciousness, I can hear all sounds coming back to me (ringing included), exactly as if they had been turned off by my brain during sleep and are now being turned on again.

Same experience here.