I dont think that tinnitus is caused by lack of sleep merely and only.
But i was surprised by the effect of lack of sleep in the perception of ghost sound as in tinnitus...
I think that it is interesting and may suggest to some to try method to sleep better as not a cure but a helping way in some experiment...
Stress and tiredness may certainly increase our own felt perception of ghost sounds ...
Dunno about tinnitus - I’ve had it for decades; it went along with my loss of high frequencies and I’ve worn hearing aids for over 20 years, and sleep has not been an issue for most of that time, but good sleep can help with many an ailment.