You can't just take crap data and compare it to a hard outcome and claim victory if you find a correlation.

Crap data is crap, no matter what you compare it to.

you're wrong. The only evidence we have for gravity is the correlation of mass and attraction. The theory of gravity does not contain any hint of a reason why, it simply points out what we can observe. Correlation is the only evidence we have.

And you have not ruled out that complaining about sleep in various ways isn't a direct side effect of brain shrinkage so the hypothesis remains open.