what is your natural circadian rhythm... morning person, night owl, something in between?
I'm naturally a night owl, and want to got to bed between 6am-8am and sleep for about 6 hours total. Anything outside of that is a fight, and I just don't get any sleep. Early mornings, or just mornings, for me, are like a 90 year old trying to pull an all-nighter... I drag my ass no matter what "sleep hygiene" BS I try (I did that for a full year, never adjusted, and my sleep was much worse). I was like this before the ptsd, it's just my natural circadian rhythm. Ptsd amplified what my circadian already wanted, but didn't fundamentally change my circadian rhythm. Ptsd or no ptsd, I'll just never be a morning person, and will always be a night owl.
If your circadian isn't naturally a night person, you might be able to shift your sleeping hours a bit, but nothing extreme like staying up ALL night and sleeping ALL day. It might be more like staying up later, and "sleeping in". Try it in steps, and be prepared to go back to earlier hours if you feel worse.