I have to say, I can't imagine not being able to sleep properly after biking all day. Exercise, fresh air, sun, and plain old exhaustion means that unless there are specific loud noises going on during the night, I'm out like the proverbial light.
This is obviously your kryptonite, but after all that work during the day and not being in "work mode" and all that stuff in our lives, thats a drag you don't sleep. Proper sleep is right up with proper food, not enough and the candle starts getting shorter doesnt it?
I have this trouble when I am not on bike trips, too. It leads to stress, weight gain, high blood pressure, and all sorts of other bad things.
I was once awakened by the sound of cockroaches laying eggs on a paper bag.