My DS8 didn't sleep through the night until after he was 4.
He was a baby who would catnap for 20 minutes and then be off for the races again. We tried the ferberizing thing once. (an only once!) He screamed for over an hour until he was so upset that he puked everywhere. He literally got so angry over the injustice of being left to cry it out that he would not calm down for at least an hour or two afterwards. (I think he was about 2 at the time).
Jr did this. At 3mos we both were so exhausted and he somehow turned off this monitor such that we did not hear him for a while. He was so upset when we picked him up that he balled for an hour and was banging on me with his little hands - even after he ate.
His last real CIO spell at 4mos was in my FIL's car with my MIL in traffic. He still gets upset when he hears her voice and cries just when he can SEE FIL's car. If we sit with him in it, he goes ballistic, struggling to get loose. His grudge is upsetting to my MIL for obvious reasons.
