"There are good times to sleep-train and periods when it may be less likely to work," says developmental psychologist Isabela Granic, Ph.D., coauthor of Bed Timing: The 'When-To' Guide to Helping Your Child to Sleep. "This is because infants and toddlers go through mental growth spurts that make them especially clingy, fussy, and prone to night wakings. They're learning new cognitive skills and often don't sleep as well."
"My 3-month-old doesn't sleep through the night, and it's fine with me. I keep her in her crib or a bassinet until her 3 a.m. feeding, and then she joins my husband and me until we get up for work. She won't go in her crib unless she's already asleep, usually from nursing and rocking, but she'll fall asleep in her bassinet beside our bed. She's happy and we're happy, and even if it goes against the wisdom of the experts, it's working for us."
“You’ll never sleep again.” Sound familiar? There’s a reason this cliche is often repeated at baby showers: In those first few months of parenting, before baby has an established sleep-wake cycle and needs to be fed only every few hours, sleep is fractured and confusing, with a long stretch just as likely to occur midafternoon as it is in the middle of the night. And that’s normal. But once baby is a few months old—after she’s dropped those middle-of-the-night feedings and has established a somewhat predictable sleep-wake cycle—sleep training her can help your whole family get some much-needed nighttime shut-eye. Here, what you need to know before choosing the best sleep-training method for your family.
If your baby is older than six months, don’t worry, McGinn says: “It’s never too late to develop good sleep habits.” Dickinson says he finds nine months to be a bit of a sweet spot for parents in terms of getting babies to sleep through the night. “They are at a good age for understanding routines and don’t need to eat during the night,” he explains.