I've started putting on guided meditations to sleep at night. The deep breathing work they do is good for training your parasympathetic nervous system (the "rest and digest" opposing force to "fight or flight,") basically teaches you to use breathing to slow your heart rate. I find it helpful to count longer on the exhale. I've actually watched on a pulse oximeter before, and my bpm will increase on the inhale and decrease when I exhale.
The meditating is also nice just cause it gives me a distraction. I can focus on the soothing voice and gentle words, and it helps me relax. Like a bedtime story for a little kid, almost.
My therapist told me once that while sensory deprivation is helpful for most people when they sleep, PTSD, ADHD, anxiety, and other issues where your brain is often "too alert" (hypervigilant) sorta flips that script. She said a lot of us with brains always watching for danger, stimulation, or both (like me, hi, C-PTSD, ADHD, and panic disorder here,) will sleep better if we've got a little light and a soft, familiar sound, like music or my meditation videos, because both falling asleep and when you wake up in the night are times when you're disoriented and groggy and just having those little cues that you're home, in your bed, and everything is safe, can be enough to keep you from ruminating or panicking.
I totally get that. Sleep is nearly impossible for me if I don't feel totally secure in my environment. I went out of town with a friend for a weekend and maybe got 3hrs total from the 3 nights at the hotel. The final night there I didn't even go to bed cause I knew our flight was early and I'd just be tossing and turning, listening to the weird hotel sounds and my buddy snoring, worrying about how tired I would be when our alarm went off. Once I was home with my cats and my meditation video, I was out like a light.
Oh, that's another thing, I call one of my cats "my tiny sleeping pill" sometimes, cause she'll wait till I get the blanket how she likes and then curl up into a purring little ball at my belly. She was the only way I could sleep some nights during my abusive relationship. So, another tip would be to get a cat, I guess, but it's gotta be the right cat, cause my other one eats his feelings and wakes me up sometimes cause he was bored and ate enough to see the bottom of his dish (how dare.)