The study looked at two sleep-training methods known as controlled comforting and camping out, both of which let babies cry it out for short amounts of time. Controlled comforting requires the parent to respond to their child's cries at increasingly longer intervals to try to encourage the baby to settle down on her own. In camping out, the parent sits in a chair next to the child as he learns to fall asleep; slowly, over time, parents move the chair farther and farther away, until they are out of the room and the infant falls asleep alone.
While neither strategy is as extreme as letting babies cry all night by themselves, they have been criticized over concerns that they may cause long-term emotional or psychological harm in babies, interfere with their ability to manage stress or cripple their relationship with their parents.
The new study by Australian researchers involved 326 children who had parent-reported sleep problems at 7 months. Half of the babies were put in the sleep-training group, in which parents learned helpful bedtime routines as well as the controlled-comforting or camping-out technique (parents could choose which strategy they wanted to use), and half were put in a control group that did not use sleep-training. The researchers followed up with the participants and their parents five years later. (By the study's end, about 30% of families had dropped out.)
By age 6, the researchers found no significant differences between the kids in either group in terms of emotional health, behavior or sleep problems. In fact, slightly more children in the control group had emotional or behavioral problems than in the sleep-trained group.
Researchers also found no differences in mothers' levels of depression or anxiety, or in the strength of parent-child bonds between families who had used sleep-training and those who hadn't.