I never did slow down. Still haven't. Don't plan on ever doing so. It is who and what I am now. Shit, I brag about being able to do most anything faster and more efficiently than others. I quit worrying about not sleeping and celebrate when I do.
I just found better ways to channel those symptoms into tools. For me that was easier and more efficient. They are still there, but now they are being forced to make them advantageous to me.
Can't sleep? Get some shit done(in my case school and about 20 different hobbies) or get some serious game time on the PC in. Paranoid as hell and not able to NOT see every frakkin' detail of everything going on? Build a really obscenely difficult model kit. (Note: been working on some of them for years now...but they are there for me when I need them!) Loud noises, kids, traffic, planes over head making me jumpy? Bose noise cancelling headphones and some industrial metal solves that problem.
For me the trick to the beast is to make it my bitch. I don't work for it, it works for me. Not a perfect solution and likely not a solution for most, but sometimes just experimenting to find what does work is a laugh riot in itself. I have my good days and bad, but as the years go on I find the good outweigh the bad, and the bad are easier to deal with.
And when none of that works, I find somewhere quiet to curl up in a ball and feel sorry for myself for a while. Then I get pissed off at myself for doing so, lace my boots back up and force myself forward.
What makes us different from civvie PTSDers and civilians in general is we adapt and overcome. They weren't trained to do so.
(Suddenly I just understood the "Semper Gumby: Always Flexible" joke they bounce around here.)
