For a fistful of coffee

I had a day off today and used my time for an experiment. I already wrote that I cant drink any coffee after 11 in the morning or coke after 8ish in the evening, without having to fear a sleepless night. In the last 5 weeks or so I have been drinking coffee here and there after that time and I could sleep. am wondering if this is just possible because I'm completely knackered or not. So today, I wanted to know it. I had coffee at 5 in the afternoon. And I'm still awake. It's quarter past 2 continental time. I guess, I will tell you tomorrow how this fistful of coffee has been dissolved in sleep.