Sleep elusive...

I've been having some problems falling asleep lately. Not every night, but about every 3rd night, two maybe three nights a month. It's really starting to become a problem. Every time it happens I go to bed the next few nights worrying that it will happen again, which of course, makes it even more likely to happen. Then it just goes away for a few weeks until one night, with no warning or any discernible reason, I go to bed and lay there for 2-4 hours until I drift off into a light nap from which I wake frequently, and then it's time to get up and start the day. On a normal night I usually fall asleep within 5 minutes. I've tried sleeping on the couch (trying to sleep, anyway), trying to sleep with the TV on, reading, warm milk, earplugs, and I don't know what else. Nothing seems to put me out. Tonight it's lasting a bit longer than normal, I'm approaching the 4 hour mark here. And I'm supposed to be at work early tomorrow to cover for somebody else. I should be in top form. Right now it's 3:33 and I have to be at work at 9. I don't really do well when I get less than 6 hours of normal sleep, these nights really make me useless the following day. Ah, jeez. Guess I better go lay back down and see if I can't nod off for a few minutes.