Insomnia

Midnight is the first minute of a new day - Gil Scott-Heron.
My night-time sleeplessness is back. On a good night, I'll get three hours of sleep before I'm awake; some nights it's an hour-and-a-half. (I've got a pretty reliable 90-minute sleep cycle.)
It's not good. I know it. I read the stuff in the journals about the effects of lack of sleep. During the night, I might get another sleep stint on the couch and, depending on the day, I may need and get one more more. Rarely does it add up to more than six hours in a 24-hour period.
I'm in my head often enough to know some of the things that I'm thinking and feeling that accompany the insomnia. I can't say that those things cause my lack of sleep, only that they're there at the same time.
The coaching that I've received suggests exercise, quiet time before bedtime, no caffeinated products after noon or so, no heavy meals late in the evening. There are also positive things to do, such as variations on meditations, relaxation responses, listening to the radio, not listening to the radio.
I'm also taking a prescribed sleep medication that's supposed to have a long half-life and so should help me stay asleep longer. (I rarely have trouble falling asleep at the prescribed time, between 10 and 10:30.)
I don't say that noting works for me. I just haven't a reliable combination of practices. Yesterday, for example, I walked five miles, half in the morning, half in the afternoon. I did have one diet Coke with supper, about three hours before bed. I also had a stimulating conversation during dinner out with a couple of friends. Lights out at 10:30, awake at 1:30.
For the past couple of years, I've kept detailed notes about the amount of sleep that I'd get each day, exercise, meals, snacks, and items of note. That data hasn't yielded anything meaningful and only adds work. So, I'm taking a break. I do keep track of my activities each day and ensure that I average 30-60 minutes of exercise each day.
Acceptance doesn't mean that I'm giving up or giving on, only that I accept that this is what's happening now and, while it's happening, I will try to make the best of it. If there are other ideas, I'll consider them and, most likely, give them a try. In the meantime, my day starts when I wake up, be it 1:30AM or some other time. Some days, my day starts several times. That's not a wholly bad thing.