We did that, with DS. We put a bedrail on the far side of the twin bed, just in case, and then pushed the two beds together. My DS would sleep two or three hour stretches if he could sleep a few feet away from me, but if he was in contact, he would wake up every half hour all night. (I had two babies in the bed, plus me and DH, and there was no room for him to be at a distance.) But he needed side-lying nursing to fall asleep, and I got so cramped trying to scrunch into the side-carred crib to nurse, so what would happen is I would nurse him in the twin, then slip into my own bed, and then climb in with him when he woke, and then slip away again. I think I got less sleep for the first few days, because I was trying to stay awake long enough to get back into my own bed when he was done-- but after a few days, he started sleeping longer stretches, so I was able to sleep, too.