> Tinnitus is the world's most common phantom percept, and yet there is no known cause or cure, despite a long list of hypotheses.

When we remember that our brain models the world based on signals and predictions, rather than having direct access to "the world as it is", it seems reasonable that there are "misperceptions".

> "The Oxford researchers proposed that the large spontaneous waves of brain activity that occur during deep sleep, or non-rapid eye movement sleep (non-REM), might suppress the brain activity that leads to tinnitus.2

I have a permanent tinnitus and my watch tells that I have a low level of deep sleep. I wonder how I could improve my deep sleep? (I am retired, live on countryside and have some physical activity)