I don't know if it's a lot, but I drink 3 cups a day, with the last one usually around 6pm, and I don't have any trouble going to sleep around 10-11pm, usually fall asleep the second I put my head down(but then I never had any issues going to sleep).
Going to sleep is the easy part. The quality of your sleep is the thing :) The biggest problem is that you don't know how good/bad your sleep is, unless you make some changes to your lifestyle (e.g. starting or stopping with coffee).
