There is no right or wrong method of sleep training; it all comes down to your unique baby and your unique parenting style. What works well for some babies does not work well for others, so do not be surprised if the techniques your friends or family members recommend don’t work the same way for your baby. The bottom line is to choose a technique that you feel comfortable with, and that you think will work well with your baby’s temperament.
Proponents of these sleep training methods say it's okay for your child to cry when you put him to bed and leave the room, although they don't advocate letting a baby cry indefinitely. Typically, these methods suggest putting your baby to bed when he's still awake and allowing short periods of crying punctuated by comforting (but not picking up) your child.
"As you modify your baby's sleep behavior, you are going to have to give up middle-of-the-night crutches, known as negative associations, that may get her back to sleep in the short run but won't prevent her from popping up again in an hour. She may resist the change. The behavior may even get worse before it gets better as she adjusts to new routines, to new positive associations."
The most well known cry it out technique is the one developed by pediatrician Richard Ferber, director of the Center for Pediatric Sleep Disorders at Children's Hospital Boston. Ferber says that in order to fall asleep on their own and sleep through the night, babies have to learn to soothe themselves. Ferber believes that teaching a baby to soothe himself may involve leaving him alone to cry for prescribed periods of time.
Most sleep coaches say the ideal time to start sleep training (or promote independent sleep, not necessarily using the cry-it-out method) is based on your baby’s development, but is usually somewhere between four and six months, when your baby hasn’t had much time to get used to nursing or rocking to sleep. At this stage, most babies are also developmentally ready to learn the skill of falling asleep on their own, explains Jennifer Garden, an occupational therapist who runs Sleepdreams in Vancouver. Around four months of age, some babies go through a sleep regression because their sleep cycles change and there are longer periods of lighter sleep per cycle. “It’s a great time to work on independent sleep skills,” says McGinn. Other babies’ slumber derails around this time because they are working on new skills, like moving around and rolling. Some parents choose to wait until things settle down before embarking on a sleep-training method, but you don’t have to, says McGinn.