Though many of the parents I see in clinic have put up with terrible sleep for years, sleep training is a safe and effective tool to help babies learn to soothe themselves at night. For this guide, I reviewed the literature on infant sleep. As director of the Pediatric Sleep Center at Yale University, I have extensive experience helping families to address sleep problems. I have also written a book on the topic, which was inspired by sleepless nights with my own children.

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.


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.”

Sleep training is a loaded phrase, and one that is often used synonymously with letting your baby self-soothe, or “cry it out,” but that’s not the whole picture, says Alanna McGinn, a certified sleep consultant and the founder of Good Night Sleep Site. “It’s more about being able to teach your baby that they are capable of falling asleep independently,” she says. You want your baby to be able to nod off on their own—ideally without nursing, rocking or using a pacifier—because whatever tools they use to fall asleep at bedtime are the same things they’re going to wake up looking for during the night. Yes, this can feel unloving and even downright cruel. You’ll find experts on both sides of the issue: Breastfeeding advocates say it’s normal for babies of all ages to wake up multiple times to nurse, and even the sleep coaches interviewed for this article disagree with how much crying and distress are acceptable.

×