Sleep training can be controversial, and many parents worry that letting their babies cry themselves to sleep could lead to bonding and psychological issues.
But a small new study adds to the growing body of research that supports the popular method known as "graduated extinction," or controlled crying, as safe and effective. And it found that a gentler method called "bedtime fading" works, too.
"We hope this study promotes health conversations about helping babies, and their parents, sleep better -- if needed," said Michael Gradisar, an associate professor and clinical psychologist with Flinders University in Australia and an author on the new study, published in Pediatrics on Tuesday.
He and his colleagues conducted the small clinical trial in a group of 43 babies age six to 16 months whose parents believed had a sleep problem. To qualify, parents were asked if their babies had a sleep problem, and parents simply answered "no" or "yes."
One group of parents learned graduated extinction, which tends to be lumped into the broader category of cry it out methods, popularized by Dr. Ferber. These parents slowly extended the amount of time they waited before going in to attend to their crying babies: two minutes before the first check, then four, then six until the baby fell asleep, and so on for seven nights.
In another group, parents practiced "bedtime fading." Caregivers picked the bedtime they'd like for their baby (say, 7 p.m.) then pushed it by 15 minutes for a few nights, then by a further 15 for a few more nights if the baby was still struggling to fall asleep. The idea is that once babies are tired because they've been pushed a bit past their usual bedtimes, their so-called sleep pressure builds, and they more easily learn to put themselves to sleep. (The researchers have published the full guidelines for the various techniques online for interested parents.)
Both interventions led to improvements in the babies' ability to fall asleep after one week, Gradisar told The Huffington Post. On average, babies in the controlled crying group fell asleep 13 minutes earlier than those in the control group, and the number of awakenings they experienced throughout the night was cut in half, from an average of three wake-ups to one-and-a-half over the course of a month.
Babies in the bedtime fading group fell asleep 10 minutes faster than babies in the control group, however they continued to wake up with the same frequency throughout the night.
The researchers weren't content with simply measuring short-term success; they also wanted to look for any potential long-term problems, so in addition to tracking parent-child bonding, they measured the amount of cortisol -- the primary stress hormone -- in the babies' saliva before the study as well as at a 12-month checkup and found that the levels stayed largely the same. While they did not measure cortisol levels during the sleep training itself, the researchers believe the measurements provide strong evidence that sleep training does not cause long-term stress.
"Extinction-type techniques that involve delaying a parent's response to their child's cries do not cause chronic increases in the cortisol stress hormone," Gradisar said. "On reflection, this does make more sense as three nights of graduated extinction is not enough chronic stress to result in elevated biological markers of stress." The researchers also found that in the initial month of sleep training, self-reported maternal stress levels improved in both the controlled crying and bedtime fading groups, and though the researchers did not explore why, it may be that navigating bedtime was no longer as difficult.
The new trial joins a small 2012 study, also out of Australia, which followed-up with parents who tried controlled crying after five years and found no differences in their children's stress levels or relationships with their parents. That study also found that the children's sleep abilities had all pretty much evened out by age 6.
The goal of all this research is not to try and convince parents that sleep training is necessary, Gradisar said. Rather, it's to reassure parents whose babies are struggling to fall and stay asleep that it is a safe option if they feel it is necessary for their families.
The findings don't, however, attempt to offer up a solution for parents in those intense, early months when babies are up frequently through the night and mothers and fathers are dangerously exhausted. The researchers only included babies age six months and up, because that is the age at which point their 24-hour body clock has truly developed, Gradisar said, as has their ability to build up sleep pressure. Newborns and young babies do not have their days and nights sorted out yet, and must wake to eat every few hours. In other words, at that point it's really a matter of waiting it out, not crying it out.
Editor's note: The headline of this story was updated to more accurately reflect the study. We apologize for our error.