But a new Australian study may provide some reassurance to those who are trying to sleep train an infant. The study finds that there are no long-term emotional harms linked to two popular behavioral sleep interventions.
"Parents can feel confident using, and health professionals can feel confident offering, behavior techniques, such as 'controlled comforting' and 'camping out' for managing infant sleep," claims the study, published online in the journal Pediatrics on Monday.
Researchers tracked 225 children who were enrolled in the study when they were 7 months old and experiencing sleep problems, through age 6. Half underwent some form of sleep training, either "controlled comforting" (often called "graduated extinction") or so-called "camping out."
Graduated extinction is essentially a modified cry-it-out method, in which parents let their babies cry and respond to them at increasing intervals in order to teach them to self-soothe. In camping out, parents sit or lay in their babies' room and may pat or stroke them while they are in their crib, but do not feed or cuddle them to sleep. Gradually, parents move back from the crib and eventually out of the room.
"The key to both of these methods is that you put the child down when he or she is drowsy, but awake," said Dr. Kyle Johnson, a pediatric sleep specialist with Doernbecher Children's Hospital at Oregon Health & Science University. "You have them fall asleep on their own at bedtime. It's a learned behavior."
At age 6, the children in the study who'd received some form of sleep training as infants were no worse off than those who had not. Researchers measured outcomes such as emotional behavior, psychosocial functioning, sleep quality and stress levels as well as how close children were to their parents.
However, children who underwent sleep training did not experience any lasting benefits, either. Yet in an earlier study using the same pool, the researchers did find that sleep training helped moms' mental health and children's sleep through around age 2.
Despite those potential short-term benefits, "unproved concerns about [behavioral sleep techniques] are limiting their uptake and provoking vigorous debate," the authors write. For example, opponents of cry-it-out methods point to research that has linked persistent crying with later hyperactivity problems.
"Parents often [and] very appropriately ask questions about 'What does having my child cry at bedtime for a number of nights mean in the longterm to them?'" Johnson, who was not involved with the research, told The Huffington Post. "This study is very reassuring in that there does not appear to be harm."
But Johnson stressed that the way parents approach sleep is a complex and personal issue: Just because the new study found that there are no long-term harms from the two sleep-training methods does not mean they are appropriate for everyone.
Indeed, the authors of the new study caution that there might be groups of children, including those who have experienced early trauma or who are especially anxious, for whom the techniques might do more harm than good. Further research is needed to determine if that is the case.
"This paper is not saying that this is the right way or the wrong way," Johnson said. "What it is saying is that there does not appear to be harm induced in a child over the long term -- at least five years."