Can anyone tell me how you go about getting a sleep study done?

I have tried everything now to try and get a good night's sleep, but for at least the past year, I've only been able to average about 3 1/2 hours per night (according to my monitor).

I've spent the last month monitoring my calorie intake, my calories out (from my monitor), my daily exercise, daily steps, and water intake. No discernible pattern has emerged. Although I did lose 8lbs. I could keep calories to 1800, walk 10,000 steps, have over an hour and half of exercise, and on one occasion slept 7 hours (a record for me) and on another, slept only 35 minutes. Same with low exercise days or high calorie days. There does not appear to be any connection for me between diet and exercise and my sleep. This really was my last hold out that I was trying for...

I've tried calming teas, stretching/yoga, showering before bed, changing things about my sleep environment...I know it's a lot related to my PTSD, because things startle me awake in the middle of the night, or I have nightmares, or sleep paralysis and then have sleep anxiety because of the paralysis.

My pdoc has been treating the sleep issues up until now. So who do you go to for sleep issues? A GP? Or a neurologist? Does anyone have experience with this process?

Thanks,
Seesaw