I have alot of problems with nightmares and flashbacks. Some things that I have found that help me -

Having a set routine for bedtime I don't go time wise because time and I have never matched on anything, Oh I can go to bed every night at the same time at least this body can but I am not always mentally aware. I can start out going to bed on time but if there is a trigger to be found my head will find it be it a sound, something I see, smell, and so on and Im off floating in lmy mental safe place while my brain has my body acting from unconscious memories. and vice versa I can just get up and suddenly find myself right back in bed. When these things happen to me even though minutes, hours, days and so on have gone by

for example if I wake up on monday at 9am and then something triggers me and I go floating off to la la land, it may be 3 am tuesday morning calender and clock wise but when I become aware mentally I just woke up monday morning at 9am in the morning and Im rested and ready to go get things done that I had planned for monday.

or vice versa I have a busy Monday and go to bed at 11pm and get triggered by something. clock and callendar wise It may be wensday 8am when I become aware of things but mentally for me its still Monday 11pm and Im exhausted from a busy monday.

So when I started working on my nightmares I knew for me I cant depend on being in bed at a set time every night and wake up feeling like I got sleep.

So instead I focused on other routines - no matter what time I go to bed be it 11pm or 11am, each and every time I am going to bed while aware I do the same things in the same order, that way my body automatically no matter when I go to bed will kick into sleep mode.

Everyone has their own things that help them to relax mine happens to be a lot of things - a hot bath, relaxation tape that my therapist and I made during therapy sessions of doing relaxation visualizations, relaxation music such as Atmospheres, and a childrens lulaby CD by my favorite singer who recorded some childrens stuff after she had her children, journal writing, drawing, playing a few on line games... anyway I picked items from my list of comforting and relaxing activites and I do then every time I go to bed.

Specifically for nightmares - my therapist and I recorded a Belleruth Naparstak relaxation visualization that is specifically geared for using for calming down and relaxing and going back to sleep after a nightmare. Before that after I had a nightmare I would get up take a bath and write a journal entry and then go to bed to one of my instrumental relaxation CD's

Specifically for flashbacks when I first started experiencing them I was seeing a rape crisis counselor. once she figured out what was happening by my going to her during one because I was unable to explain it to her. She told me the way to make them go away was head on through it - draw it, write it, talk about it, create craft projects about it if you are interested in crafts and so on. Doing these things "desensitizes" the person from the situation that happened to them - basically focusing on it so much that you get used to it being there and it fades away because it no longer bothers you because the brain had jumped out of the broken record phase of denial and shock that it happened and into healing.

The way to set up your own relaxation routine before bed is pay attention though out the day of how you are feeling and what things make feel calm and relaxed. those things are what you use to make up your own custom made bedtime routine,

pick some of them that you know that you will do every time you go to bed so that you brain forms a habit of calming and relaxing yourself.

hang in there