I've stopped drinking coffee at all and I'm way less tired. Before doing this, I wasn't able to start to watch a film in the evening without falling asleep.
I tried that for a month. I was exhausted, until I started drinking coffee again. I'm not usually a heavy drinker either: a couple of cups, usually before noon.
Are you all drinking coffee black? Maybe it's not the coffee but the sugar if you use it? That stuff totally messes with me.
It's definitely anecdata, but I only drink coffee black, and if I have any past about 2pm I won't get to sleep until two or three AM.
My experience is similar. If I have coffee or tea after lunch, I have trouble falling asleep at night. However soda or iced tea seems to have no effect sleepwise.