Most experts recommend starting when your baby is between 4 and 6 months old. By about 4 months, babies have typically started to develop a regular sleep-wake cycle and dropped most of their night feedings. These are signs they may be ready to start sleep training. Many babies this age are also developmentally able to sleep for long stretches at night.
"I have a 3-month-old who I rock at night. He falls asleep very quickly (much quicker than if I leave him in his crib). If he wakes in the middle of the night, we go to him and comfort him. We don't take him out – we just help soothe him. Why make him feel lonely and abandoned? I have no problem losing a little sleep if it means that he feels like we will be there for him."
McKenna advises against sleep training and encouraging babies to sleep for long stretches at night. Instead, he urges parents to follow their babies' cues and allow them to wake frequently through the night to feed. A strong advocate for co-sleeping, McKenna encourages bed-sharing and other co-sleeping arrangements, such as putting the baby in a bassinet or crib at the parent's bedside, while also following standard SIDS safety precautions – for example, making sure there are no blankets or stuffed animals around him.
Prepare yourself for a few difficult nights. Hearing your baby cry can be excruciating, as every parent knows. During the waiting periods, set a timer and go to a different part of the house, or turn on some music, so you don't have to hear every whimper. As one BabyCenter parent says, "The first week could be rough. Try to relax and know that when it's all over, everyone in your household is going to sleep more easily and happily."
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.