Sleep training: almost every parent has an opinion about it. Those who have done it successfully, and are sleeping peacefully through the night, can be downright evangelical about it. Others believe that it’s cruel and unnatural to let a baby cry himself to sleep and even suggest it causes babies permanent “damage.”
It’s a disturbing claim, one for which there is no evidence. Still, in her new book, First Year Essentials: What Babies Need Parents to Know, British parenting expert Penelope Leach says she has proof that “crying it out” mentally damages babies. How? According to Leach leaving babies to cry causes levels of stress hormones like cortisol to rise to the point where they are toxic to the developing brain. A crying bout of half an hour or more, the typical period of time a child cries in the course of “sleep training”, could, according to Leach, cause brain damage. “It is not an opinion but a fact that it’s potentially damaging to leave babies to cry,” Leach told the British Newspaper, The Indpendent. “Now that we know that, why risk it?”
But where is the research that establishes this “fact”? So far Leach hasn’t revealed her sources, though a slew of recent child development research finds no evidence to support her argument.
For example, a new report1 from the Harvard Center on the Developing Child paints a somewhat different picture. The working paper, which surveys the latest research in neuroscience, and developmental psychology, explains that “experiences like abuse and exposure to violence can cause fear and chronic anxiety in children and that these states trigger extreme, prolonged activation of the body’s stress response system.”
Animals subjected to chronic stress over prolonged periods, especially during sensitive phases of brain development, can have long term physical and psychological problems as a result. Elevated levels of cortisol can negatively effect the parts of the brain, particularly the prefrontal lobe, which is associated with executive functions like, decision making and impulse control. The authors of the Harvard report speculate that “persistent fear and chronic anxiety” could have a similar effect on children.
So, according to this study, there are events — such as child abuse and exposure to violence that can have severely negative effects on brain development. But nowhere does this report cite crying it out as one of these events, and commonsense would say that it is not the same thing.
At least one study of the long term effects of sleep training agrees. Researchers at the Murdock Children’s Research Center in Australia are conducting a longitudinal study of infant sleep. A study released last month reported on the progress of 225 children whose parents used “controlled crying techniques” to get their children to sleep. At age 6 there were “no adverse affects on the emotional and behavioral development of children or their relationship with parents” as compared with kids who did not “cry it out”. Another analysis found that sleep intervention in infancy greatly reduced children’s sleep problems later on and led to less depression among mothers.
It has been Leach’s long standing belief that crying it out hurts babies. She claims that the “science” is behind her, but can’t be bothered to share it. Her prejudice, which is she shares with many other parenting gurus, most notably William Sears, is that parents can’t be trusted to do what’s best for their children. They’ll admit we love our kids, but believe we’d throw our babies’ prefrontal lobes under a train to get a decent night’s sleep. That’s why we need experts like Leach to speak for the babies.
It is possible that Leach may come up with a study out there I just haven’t been able to find, but even if she did find research appearing to support her claims, we should be skeptical. Why? Because there is far more to the parent-child relationship than we can capture with research, especially research about crying.
Unlike animals which cry in distress human beings cry for all sorts of reasons. We cry from pain or embarrassment, joy or grief. Babies may cry from hunger or frustration, in pain or simply with exhaustion. We are the only creature that sheds tears and their very composition varies depending on why we weep; tears of grief are chemically different from tears of pain.
Crying binds us together. Our children’s tears clutch at our hearts, stimulate nursing mothers to lactate and sometimes make us weep along with them. No one really knows why we cry but, like the love of music or infectious laughter, it goes right to the heart of what it is to be human. It is biology mediated through human relationships. It’s in that context that we need to see crying it out. It’s an experience that is unique to the people involved and therefore, very difficult to study.
What works for one may not work for all. In any case, the answer to the question “what’s the right thing to do” is a question for individual families, not neuroscientists or parenting experts. — Nancy McDermott
1 National Scientific Council on the Developing Child (2010). Persistent Fear and Anxiety Can Affect Young Children’s Learning and Development: Working Paper No. 9. http://www.developingchild.net