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.
Not to be confused with the bedtime-routine fading technique described above, bedtime-hour fading involves putting your baby into the crib at the time they usually end up dozing off, and making that their new bedtime for a couple of nights, and then gradually moving it to an earlier time. For example, say you always put your baby down at for the night at 7:30 p.m., but they tend to fuss or cry in the crib for 20 minutes or more, until they finally nod off around eight. This means 7:50 to 8 p.m. is actually their “natural bedtime,” even though you’d like it to be earlier. To figure out when your baby naturally falls asleep, keep a diary for a few nights to track when they finally settle for the night. (Using a video monitor can help with this.) A few nights later, move the whole routine 15 minutes earlier. Continue moving the bedtime earlier by 15 minutes each night (if needed) until your baby has shifted their old habits to nod off at the desired time instead of the later one.
If your baby is growing poorly or is difficult to console, you should talk to your child’s pediatrician to ensure that your child’s sleeping difficulties have no medical cause. Likewise, if you are struggling with depression, it is critical to discuss this with your child’s pediatrician as well as your own physician. Poor sleep can prolong postpartum depression in mothers.
Exhausted parents may be eager to get training underway—so how do you know when to start sleep training? “Most infants are ready for some sort of sleep training at 4 to 6 months,” says Lauren Kupersmith, MD, a clinical instructor at the department of pediatrics at NYU Langone Medical Center. “While some pediatricians adhere to the guidelines that infants are ready to be sleep trained when they achieve a particular weight, I feel it’s much more appropriate to wait until they are developmentally ready to self-soothe, at about 4 months old.”
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.
Sears emphasizes a nurturing, child-centered approach to sleep and warns parents to be wary of one-size-fits-all sleep training. He recommends patiently helping your baby learn to sleep in his own time. He encourages co-sleeping, rocking and nursing your baby to sleep, and other forms of physical closeness to create positive sleep associations now and healthy sleep habits down the road.

Yes. Multiple studies have shown that sleep training is both safe and effective, without any studies showing evidence of harm. The best long-term study followed 326 children for the first six years of life. The authors reported that children who had sleep trained via any method in infancy slept better at 2 years of age than children who were not sleep trained, and their mothers were less likely to be depressed. Several years later, the researchers looked at these children again and noted that there was no evidence of emotional or behavioral problems in children who had been sleep trained versus those who had not. As part of this follow-up, the researchers measured the children’s levels of the stress hormone cortisol, which is frequently cited by opponents of sleep training as the mechanism by which crying affects developing brains. The researchers did not find any evidence of differing levels of cortisol secretion between children who had been sleep trained and those who had not.


But when he was about three-and-a-half months old, the routine fell apart. “I would feed him, but he wouldn’t be asleep at the end of the feed,” recalls Welk. “I would rock him until he fell asleep and put him down, and then he would wake up 30 minutes later and I would do it all over again.” Desperate for some rest, Welk brought Greyson into bed with her, but then she ended up just lying still, holding a pacifier in his mouth all night long. “I didn’t know anything about sleep,” says Welk. “I didn’t know you couldn’t just rock them to sleep and then put them down.”
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