I take prazosin for nightmares. It works really well and isn't sedating at all. It actually helps with flashbacks as well for me. I have a low BP too but it's not so low that I can't take it. I started it in the hospital and the first night I took 1mg and that didn't help but the next night it started working at 2mg so you don't really need to build up levels in your system.
Hope it helps you if you do decide to start taking it.