Caffeinite'd
I made a big mistake yesterday. We had a friend visiting us in the afternoon and as is customary the coffee was obviously served. And letting your quests to drink alone just doesn't feel right either. So I had a cup myself as well.
There were times when I could drink half a pan of coffee right before going to bed and sleep like a baby. After gradually lovering my dose all the way to just one (or rarely two) cups in the morning the effect of caffeine has once again returned. Just one cup after noon is able to keep me up all night.