Echoing the responses above, there could be a number of factors. It sounds to me like you aren't getting enough RESTORATIVE sleep. This could be from sleep apnea or just general restlessness. Give ZMA a try (heck, it's just 9 bucks). I feel like I get a more restfull nights sleep when I take it. You will also get some wickedly vivid dreams.
I don't know about you're sleep environment, but there could be other intangibles (noise, etc).
I also second the Tempurpedic mattress response, but if you want the same thing for half the dough, check out Absolute Comfort's mattress. I absolutely LOVE mine. I'm getting better sleep now than I did before we had kids (and one of ours is only 3months old).
Hope this at least helped a little.