I've been there. Although every case is different, you may be successful with my approach. I observed that it is much more difficult for me to sleep when very tired, and that I'm awful at auto measuring the time to go to bed. So, I adopted a rigid 7h sleep schedule for a month. I added some exercise (swimming), to guarantee success. Worked like a charm. Nowadays I'm more flexible about the schedule, but vigilant as to whether I'm slipping.

I think the most important thing I did was defining that taking one hour to fall asleep was problematic and then tackling the problem methodically. Seeing a doctor about it was on my scope had I failed to solve the problem on my own.