Long story short... I was diagnosed with Sleep Apnea. The insomnia may or may not be a result of that. My body may have been conditioned to keep me aroused to enable my breathing. On the other hand, because of health issues, my sleep position has been altered which may have contributed to the apnea symptoms. My new MD steered me into a Sleep Study. My constant fatigue and mental complaints were what prompted him to consider Apnea.
I use a CPAP/APAP machine now. This is not to say my insomnia is completely cured. I still work to recondition my body for sleep. For example, I consciously re-focus my thoughts to deep breathing into my abdomen or relaxing body parts. It is like a bad habit and you have to concentrate on breaking those contributing traits. I will say that I feel much more mentally refreshed and my body feels much better since using the breathing machine. I can feel the difference when I don't use it. It is the lack of oxygen that effects me in so many ways. I have hypopnia more so than apnea.
If you are able to have a Sleep Study I would definitely do one. It is direct method of examining your sleep patterns. It is something concrete that you can cross off your list in trying to find out the cause of your problem.