Catrin, I have had the exercise induced insomnia you described... I used to exercise almost exclusively at 5 AM. I couldn't even take a walk after 3 PM without it affecting me. Basically, I have trained my body slowly, to be able to deal with it. I still get up fairly early (5-6 AM) most days, but the exercise doesn't seem to keep me up as much. I mostly exercise in the morning/early afternoon, but I can ride at 5-6 PM and I can get to sleep, if it's not a really hard ride. It took a long time.
I'm a lot like Bleeker, in that I have had to reduce my caffeine intake to just the morning. I love having coffee around 3 PM (funny, the time I would leave work for all of those years), but I pay for it. I can't even have decaf after dinner, when we go out, so I drink herbal tea. Boring. Coffee is my one vice, so I don't like this.