N, I think you hit the nail on the head. It's not the glass- or 10 glasses for that matter, it's trying to find a way to cope, sleep, knock yourself out. Ambien+ Benadryl + Alcohol.
JMHO, but you need to knock out the trauma to sleep. The more I ran away, the faster the ptsd ran with me. It will always overpower you, and rear it's ugly head until it can be faced at some level.
I realize you are just trying to cope. Relaxing is good, and very difficult to achieve. Can you try for it in other ways that aren't reliant on drugs or alcohol?