Researchers have reassuring news for parents struggling to get their babies to sleep.

Letting infants cry it out using two specific methods won’t cause any lasting psychological harm to your children or to your relationship with them, a new study shows.

Researchers compared the long-term effects of "controlled comforting," "camping out," or usual care among infants with sleep problems.

Controlled comforting involves gradually taking longer to respond to an infant´s cries.

A slightly gentler approach called "camping out" instructs parents to sit with the child as he or she learns to fall asleep, while the parent slowly inches toward the door.

In the study, a third group of babies received usual care, in which their parents could ask for sleep tips during a well visit, but did not receive any formal sleep training from a nurse.

Previous studies have shown that controlled comforting and camping out were helpful at getting infants to sleep through the night and reducing related depression in moms for up to 16 months.

But the new study shows that some of these benefits may last until the child turns 6, and there are no long-term downsides. (The sleep improvements made by such training tend to last until age 2 and taper out by age 6.)

What’s more, sleep-trained babies were similar to infants who did not participate in formal sleep training in terms of their mental health, sleep habits, stress levels, and their relationship to their parents at age 6, the study shows.

The findings appear in the October 2012 issue of Pediatrics.

Reassuring Findings About Infant Sleep Training

"We have known for many years that these behavioral techniques are helping kids sleep better and that parents have a better night as a result," says Marielys Rodriguez-Varela, MD. She is a pediatrician at Miami Children´s Hospital. "Now we can feel even more comfortable in that we know there are no long- term consequences for these children or their parents."

A relaxing bedtime routine is also essential, she says. This may include a bath and a book and/or a lullaby so the child knows it is time to sleep.

And of course, there are other reasons your child may be crying, Rodriguez-Varela says. "Make sure they have no temperature, [or] don´t need a diaper change before leaving the room if the crying seems excessive."

Parents should take comfort in the new findings, says Lewis J. Kass, MD, a children´s sleep expert in Mount Kisco, N.Y. "Sleep training is harder on parents than kids," he says. "Most kids are good sleepers, and the ones who are not can usually be made into good sleepers with training."

It is OK to sleep-train your babies using these tried-and-true methods. "Many parents worry that letting their kids cry it out will cause some type of irreversible damage to their psyche and the parent-child bond, but there won´t be any long-term damage," Kass says.

Sleep training is a challenge for many parents, and there are no hard-and-fast rules, he says. "Most infants can distinguish between night and day by 4 to 6 months of age." 

Sleeping through the night means different things to different people. "By the age of 1, they should be sleeping 12 overnight hours in a row," Kass says.