Definitely does.

I used to wear them every night and they definitely improved my sleep. But then I also had instances where my ear was blocked with wax for several days.

YMMV

My suspicion from regular use of ear plugs is that the wax sticks to the plug every night. I use a new set every night. Pretty wasteful, but man, I need my sleep.

I can confirm. I also use in-ear headphones daily which I think exacerbates it further. It can be fixed by an occasional ear wash though.

Yeah, they can block drainage

I used to have lots of earwax buildup that kept me from using earplugs.

Then I fixed my health.