I can't sleep

So here's another solicitation for help from the readership...

I'm having massive problems sleeping, problems which have led to me feeling like crap later in the day when it's time to start writing. For the past month or so, I've only been getting about three or four hours per night, at best, and I need more. I need more, but I simply can't remain unconscious long enough to feel rested. This needs to be remedied immediately.

A little insight into my routine may be helpful...

1. I start off every single day with a fairly large cup of coffee. This is not something I'm willing to give up. I'm addicted, and will be for life, so this one doesn't get touched. I've been doing this for years, and have never had problems sleeping until recently.

2. I'm not under any excessive stress at this point in my life. Everything is actually pretty mellow, even my concerns regarding the book and my deadline.

3. I exercise very strenuously at least four times per week. Usually more. One would think this would make me sleep like a baby, but it doesn't.

4. I supplement daily with protein shakes, a multivitamin, creatine, glutamine, fish oil and l-tyrosine. I do so occasionally with l-arginine and l-carnitine. And no, I am NOT on any steroids.

5. I have tried to help myself sleep by using -- not at the same time -- both melatonin and ZMA. Neither have helped.

6. I am sleeping (alone) on a fairly good, fairly new mattress, in a comfortable, dry environment with very little noise.

7. I don't smoke, nor do I use any drugs.

8. I try to stop eating at least three hours before I go to sleep, and am usually successful in doing so.

9. I rarely drink alcohol anymore.

The problem, here, is that I usually can't fall asleep. When I wake up, no matter what time it is, I can't fall back to sleep. I read myself to sleep every night, a practice that worked like a charm until about four weeks ago. Nothing in my life -- neither my diet nor my stress level -- underwent any changes before or since this shit started, so I can't come up with a root cause for the problem.

This thing is fucking KILLING my level of productivity, so if anyone can suggest anything I can try, I'd appreciate it.