Sleeping through the night

Parents always ask each other, "Is your child sleeping through the night?" Unfortunately, Justin isn't sleeping through the night yet. What's everyone's secret? How did they do it? For the past couple of nights, Ed has slept with Justin in a separate room to allow him to "cry it out" and not feed him. It kind of semi-worked. I was lucky because I was not woken up at night and actually got about 6 hrs of sleep! :) Well, we tried it again last night, with Justin in the den next to us. He didn't sleep through the night. Justin started crying around 2:30am. I guess I'm a softy. I couldn't let him "cry it out." I thought his throat was getting hoarse and the cries kept sounding sadder and sadder. I gave in. Ed is definitely stronger than me.