I have trouble with sleep because I wake up in the middle of the night and, as soon as I wake up, my perseveration/rumination starts.
I've actually successfully combated that over the past couple weeks by taking a dose of diphenhydramine right before bed. It doesn't make me groggy or anything like that, but it does switch my brain off for the night so that when I inevitably wake up to use the bathroom or something I can fall back to sleep instead of lying awake for an hour trying in vain to get my brain to SHUT UP and let me sleep.
This is not a long term solution, and I'm going to have to stop using it soon just because it should not be used long term. I am hoping that I will have broken whatever conditioning I've managed to accidentally put my brain through that makes me go "Ding! It's time to ruminate!" when I wake up at 3 AM to pee. I know it's largely a case of "classical conditioning" but it really makes me dread the night, too. And of course fearing that it will happen, makes it worse...
As far as sensory issues go, a white noise machine has been the biggest help. I even got a travel case for mine, because I can't sleep without it.