Insomnia?

Lately, I've been having real problems falling asleep and staying asleep. I've had troubles for many years now, but in the last couple of weeks it has seemed to get much worse.

It seems that the brain does most of the sorting and thinking at night. The problem is that these subconscious processes don't stay subconscious. All of the things I've been reading, seeing, studying, hearing -- they begin to sort themselves out at night, when it's quiet and dark. When I realize it's going on, I find myself having to engage my thoughts, and I conscisously wander about in my subconscious (if that makes any sense). It's a fascinating experience, but one that doesn't lend itself to promoting sleep. The most annoying thing is that even after I think I've buried the wanderings back down into just the subconscious, just as I feel myself falling asleep, something pops back up and I discover myself engaging my thoughts once more.

If trying to fall asleep while doing that wasn't bad enough, I frequently find myself restless at night, even when I'm asleep, as it seems that my conscious brain is half awake, trying to engage the subconscious. And then I wake up in the middle of the night and stay awake for two or three hours. It's altogether very annoying.

I've tried melatonin in the past, and while it seems to help me (sometimes) with the initial getting to sleep, it doesn't keep me asleep. In fact it seems that when I do awake in the middle of the night, I stay awake even longer.

Does anyone have any suggestions for how to keep my conscious mind from engaging the subconscious at night?