Editors’ Note: The debate over sleep training is making headlines again. In her new book First Year Essentials: What Babies Need Parents to Know, British parenting expert Penelope Leach claims that “crying it out” mentally damages babies. According to Leach, extensive crying can raise stress hormones like cortisol to the point where they are toxic to the developing brain.
To date, however, cortisol levels have only been shown to be damaging in cases of chronic stress due to abuse or exposure to violence – not isolated incidents as would be the case with crying it out.
To give you the full scientific picture, we’re re-running this recent Science of Kids column. In the meantime, another study is in the works (according to this article), indicating that “controlled” crying it out is not damaging. Unfortunately, the article doesn’t specify how long the “controlled” crying bouts were allowed to go. The argument will rage on.
Ignoring baby cries during sleep training is linked to all kinds of problems later in life – ADHD, antisocial behavior, lower IQ. At the root of these claims is the idea that the stress of crying and the absence of a responsive parent release intense levels of chemicals that alter a child’s brain development. But is there scientific evidence to back this up?
It needs to be said from the outset that this is not a pro- or anti-cry it out article. How you approach sleep is as personal and complex as any aspect of parenting. And, rightly so, many moms and dads use their instinct as their guide. The intent of this article is to examine the evidence that distinct periods of children crying themselves to sleep causes long-term brain damage – a very serious claim that should not be tossed around lightly. Amid the intensity of the debate, it’s often hard to see the science through all the emotion.
The work of big name researchers and clinicians comes hand-in-hand with the anti-cry it out stance. For example, UCLA researcher Dr. Allan Schore is often cited as showing that stress hormones like cortisol, released during intense crying, damage nerve cells in the brain, leading to unhealthy attachments and psychological disorders. He demonstrates that a repeated pattern of unmet needs disrupts a child’s stress-regulating systems and can alter the way her limbic structures process emotion.
But Schore’s research is actually about how trauma, chronic neglect, or abuse affects a small person. No doubt, if ignoring distress were your every day parenting philosophy this would apply, but sleep training against the background of caring, responsive parenting, does not. In fact, this is the case with a lot of sources opposing the cry it out method – the claims of brain, personality, and attachment damage come from research conducted with grossly neglected children (some studies use data from Child Protective Services cases) not healthy children with loving parents who let them cry for an isolated timeframe. It’s worth noting that if it’s crying we’re worried about, the overall amount of crying involved in a well thought-out sleep-training program can be less than the sobs that many parents have reported when they go with a “no-cry” solution.
Another well-respected source that makes the rounds on the Internet is a list of studies put together by Dr. Sears that conclude crying it out is dangerous. There are too many to explain each here, but for example, one states that infants who cry excessively have a higher incidence of ADHD, antisocial behavior, and poor school performance. When you look at the original study, though, the crying clearly has nothing to do with sleep training. The study shows that extra fussiness and subsequent crying (regardless of what parents do in response) might be a symptom of an underlying problem that could come up later in life. Sears quoted another study as showing that crying early on makes a child fussy and emotionally unbalanced. Again, the actual study says that babies who already cry a lot might be showing early signs that they are slower to develop emotional control. None of the Sears studies listed shows negative consequences as a result of a structured sleep training program.
A Harvard study often surfaces in this debate to show that CIO is bad for baby. This is not actually an original research paper, but an opinion paper based mostly on anthropological studies of parenting practices. It describes how U.S. parents emphasize independence, while mommies from other cultures co-sleep and respond faster to their little ones. It does not have any data about sleep training.
Letting a baby cry while she learns how to fall asleep is not for everyone. You may have a philosophical issue with it, you may think it’s not the right fit for your child, or maybe it just plain feels wrong to you as a parent. If this is the case, follow your gut and find your own path to restful nights.
But when science is used as a platform for criticizing sleep training — citing the names of brain regions and neurochemicals — it’s misleading at best, and frankly feels like fear-mongering at worst. There will always be heated debate around this issue, which I think is healthy in some respects – we should be able to vet out and discuss our parenting dilemmas with each other. But remember we’re talking about opinion and personal choice. Until there is more substance on this issue, let’s leave science out of it.