I have exactly the same problem. I also tried Lunesta and Ambien, which didn't really work, and Rozarem, which is supposed to be quite similar to melatonin, and had similar but stronger effects. Nothing that worked. I also tried bright light therapy, which didn't seem to work at all, and was very inconvenient. At the moment I'm on a free sleep schedule, which seems to cycle completely every 2-3 weeks. (I'm not sure because I've never kept a sleep diary.) That's only currently possible because I'm unemployed.