Honestly, in our personalized consultations, we try to avoid this method as much as possible. If you are going to use cry it out, we recommend your baby is at least 6 months old, but preferably 10 months or older, when we expect almost all babies to be able to get through the night without a feeding. It is not for the faint at heart. We find that laying a foundation in the beginning with other strategies and techniques can reduce crying even if this method is used in the end, however.
"I have a 6-month-old who has refused to sleep longer than 30 to 90 minutes day or night since he was born! I've tried everything out there except CIO. He's strictly breastfed and relies on that or rocking to get to sleep. He doesn't know how to soothe himself to sleep, and he naps for only 15 minutes. I'm severely sleep deprived. I don't have the heart for CIO, but I think I'll try the revised method where you pat him down and reassure him lovingly while allowing him the opportunity to comfort himself. He's been co-sleeping since day one, and it's going to be tough, but I'm at my wits' end and cannot function."
"I have a 5 1/2-month-old baby girl who has never once in her life "cried it out." From night one in the hospital, she has slept with me. She is rocked and nursed to sleep and when she starts to grunt/wiggle beside me, I simply shift near enough for her to latch on to my breast, and she nurses back to a deep sleep before either of us fully wakes. I follow Dr. Sears' attachment style parenting and my baby has never once in all her life cried during the night or even fully woken up."
The age of your baby might determine what kind of sleep-training method you choose, though. You could try a gentle shush-pat technique with a five-month-old, but you’ll likely have to leave a one-year-old in the crib as they protest (cry or scream) about the new bedtime arrangement. Don’t attempt a formal sleep-training method before four months, until your baby is able to go longer in between feeds and their circadian rhythm starts to develop. (Many babies this age still feed in the night—contrary to popular thinking, sleep training isn’t synonymous with night weaning.) Dickinson says that many four-month-old babies are biologically able to go through the night without a feed, but that doesn’t mean you shouldn’t respond and feed them if other methods of calming them aren’t working. Since every situation is different, we recommend checking with your doctor before withholding your baby’s night-time feeds.