It's a catch 22. We need sleep to heal, but we need to heal to sleep.
I think getting in sleep while you can gives your body the rest it needs to heal. Therefore rest is the priority.
I think the logic behind the sleep hygiene principle of going to sleep at a set time is good and ideal. However, I think it is more important that we get a minimum amount of sleep. Think about the healthy people who have the luxury of being able to sleep at long stretches but choose to go to bed at irregular times. They end up feeling tired even though they are getting 8 or 9 hours of sleep because they go to bed at different times. For these people, being disciplined about a sleep schedule will improve their sleep. However, they are already getting a minimum amount of sleep so they have a different baseline for sleep.
However, for someone with PTSD who has trouble sleeping and likely does not get enough sleep, I think we are best served by getting more sleep. So if you are tired and want to take a nap, you might end up getting a more restful sleep at that time, than you normally would at night. It may allow your body to perform some of the processes it performs for health during this time.
For me personally, I found that the more I prioritized sleeping whenever I needed to, the better my sleep became. I did need to tolerate sleepiness a lot, but ultimately my sleep improved. There were times when I went to bed at 7 pm because I was so tired and then needed to just get out of bed at 4 am due to the early sleep time, which was abnormal. The next day, I would just see if I could make it past 7 pm a little bit but I wouldn't push myself too hard. My body adjusted. I would also go through cycles where I would not be able to sleep well for days. Then I would sleep really good for 10 hours out of pure exhaustion. The next night I wouldn't sleep well because I didn't have the exhaustion built up. But I would ride out that cycle and let my body do what it was doing. Eventually I was sleeping for 4 hour stretches consistently and then 6 hour stretches and so on.
If you sleep whenever you can, you can still do other things for sleep hygiene, like avoiding stimulating substances and activities before bed, and having a pre-sleep ritual. This will give eventually give your body queues that it's time to sleep. Also, make sure you addressing any nutritional deficiencies. Stress depletes us of important nutrients required for sleep. For me, I sleep better when I take magnesium before bed. My point is that even if you prioritize getting a minimum amount of sleep, you don't have to throw out sleep hygiene altogether. I just think we should try to force our bodies to sleep the way a healthy person does. If we have burnt out adrenals due to the constant flashbacks, our bodies might not work that way.
Hopefully, all of the different opinions give you food for thought, but ultimately it's your body and you should listen to it. What worked for me or someone else might not work for you because we are all different. You may want to experiment with different things but I would recommend honoring and listening to your own body and intuition.
