I think you are supposed to go in and rouse them slightly about an hour before their normal WU time. The other night when DS woke at 4am for a drink, he then slept til 7. This is what gave us the idea that it might work for him. He had been on NNDs for a while and still waking at 5/5:30 everyday but extremely tired in the mornings, so I knew he needed more sleep. It is a last resort, after we tried everything else. We tried short, long, early, late naps, EBT, late BT supper before bed, milk in his room for the mooning, groclock, rewards, I mean EVERYTHING. So this is really a last resort.