I usually take mine between 10 and 11 and I jump out of the bed at 6 every morning. It is a really good antioxident as well.
Thankfully, I sleep well these days but once and a while I do take 1 mg when I know I will have trouble falling/staying asleep. Even if I don't get 8 hours of sleep, I still feel like a normal functioning person in the AM when I get up - unlike the PM stuff.
I've heard that it also helps people with the seasonal disfunction problem.