Ah, we also had trouble with DS2, he only started sleeping through the night well past 2.5years. I am not a big fan of drastic measures or scientific methods, and luckily he's now started to be ok. He's never up later that 7, that's for sure, but at least he doesn't call 3/4 times per night anymore, and if he does it's just for a wee (and he can't be trusted yet to take his sleeping bag off properly. Give me time, I'll train him for that, too!)
Having said so, I am still caffeine addicted, even if now I could sleep longer :-) but I read here, Ff, books etc...