Raising a healthy sleeper starts with a consistent bedtime routine. You can start enforcing this when your baby is roughly six weeks old. At the same time every night, read a book together, sing songs, and feed your baby before putting him or her into the crib. It may also help to get your child up at the same time every morning and put him down for naps at regular times.
"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."
C.I.O. is the most famous sleep training technique, and the most controversial — although, despite its daunting name, it is safe and effective. In its simplest form, unmodified extinction, you place your infant down at bedtime, drowsy but awake, and then leave the room, without returning to check on or soothe your baby. This method will work quickly, but often produces prolonged periods of crying for a few nights, which can be difficult for parents to tolerate.