I don't know of any. I took Unisom last summer for my personal mcat inferno, but I quickly developed tolerance for it. Then took lunesta, again, my nerves resisted and wouldn't rest. The best thing to do, I think, is cut down on the caffine. If you need to have some... drink it in the morning. Even if you go to bed at 4 am, force yourself to get up at 6 or 7. Yeah! and no nap. If you are tired all day..just put in a good 4 hours and make up for it the next day.
And go to the gym everyday..you don't want to look busted after the test when you finally get to party..lol