To Cry or Not to Cry (it out) the Research Behind it.


Here’s a subject that tends to gets the blood boiling…Cry It Out. My instinct is that allowing an infant to scream themselves into oblivion, (or sleep), is mean, but since there’s so much debate, I hunted down some actual research…something a little more concrete than: my mom let me do it and I’m OK. For starters, according to API, (Attachment Parenting International, if you’ve been following my posts on that subject), makes the following claim: infants are not neurologically or developmentally capable of soothing themselves and regulating their emotions. They caution that allowing the stress hormone, cortisol, to spike in the brain can have long lasting effects on sleep patterns, behavior, and emotional reactions.

Admittedly, API is not a research center, and in fact, although I agree with their principles, they would most certainly be considered biased.

So, without further ado, here is some cite-able information about the subject.

In support of CIO:
A 2012 follow-up study looked at 225 kids who had been placed into two groups: sleep training group and control. The results were that there were no differences in terms of their emotional responses, stress, etc. I couldn’t get access to the entire study, but it was described in an article on and I’m going to have to trust their explanation, (I also found references to the study elsewhere that described it essentially the same way).

I couldn’t find anything that came to any other significant conclusions. I looked, but overall what I found was lots of stories about people who did it with their kids who all turned out OK.

In summary, CIO isn’t going to hurt anything.

Against CIO:

The first study I looked at was the one regarding the cortisol spike which had been referenced by API. I don’t have a link because the version I read was a PDF of the entire study, (OK, so I skimmed the study and read the abstract). It was done in 2011 at the University of West Texas, etc. A link to the PDF is on the CNN article referenced above.

This study measured cortisol, a hormone that helps regulate metabolism, but can spike in response to stress and is linked to a number of health conditions in adults. Cortisol in the saliva of mothers and babies was measured during a five-day CIO trial. In the beginning, the infants cried when left alone to go to sleep and cortisol spiked in both groups. After a couple of days, the babies stopped crying and the cortisol spike was seen only in the infants. This led to the conclusion that the level of stress experienced by the babies did not decrease, (they were not soothed), but rather they had stopped crying after learning that it would yield no response. The mothers’ cortisol did not spike, however, because they were not listening to their babies cry.

For starters, here’s what I learned about cortisol. Most of what I read about the dangers of high cortisol pertains specifically to adults, you can read it here. What I found about children, here, is that low levels of cortisol impacts metabolism and is related to depression. There is a disease that can cause it, Addison’s Disease, but it’s also thought that chronic stress can overwork and cause a malfunction of the adrenal glands, which secrete the hormone. Additionally, there are some researchers who suggest that in a child’s still-developing brain, it may cause even more damage. In any event, I am going to conclude that I want my kid’s cortisol levels to remain normal in both the short and long term.

While there is near universal agreement that lower stress on a mother is good for a child and a family, I’m not convinced that this should be done at the expense of the child. Furthermore, I’ll acknowledge that this study, (or at least the portion of it that I read skimmed), did not look at long-term effects.

Project SIESTA is an ongoing project at Penn State University headed by Dr. Douglas Teti. I couldn’t find the actual research, which may be because it’s still in progress, but I did find him interviewed. A portion of his research examined sleeping patterns using an overnight camera. He found that those babies who were being responded to emotionally had fewer sleep disruptions overall than those who did not. While he did not isolate CIO in this instance, and based on the article I read, this only looked at children aged 0-24 months, he stated that “the way we construed emotional availability is that an emotionally available parent is not a parent who is going to abandon a child at night and let the child cry it out.” Again, this study is neither complete nor comprehensive, based on the limited portions of it that I’ve read, but it does not support CIO.

Finally, there’s this article. It’s from Psychology Today and I don’t want to go to crazy summarizing it because it’s a good read in and of itself. It begins with an explanation of the roots of CIO being in the late 1800s and early 1900s when children were to be seen and not heard. Incidentally, this is also at time when childbirth became a medical procedure instead of a natural experience for women and you can just go ahead and assume how I feel about that “progress.” At any rate, the author goes on to explain how infants, particularly during the first six months of development, need to be responded to for a myriad of reasons, not the least of which is evidenced by a study done on rats, (they are often used for studies on human brain functioning). Here is an except:

In studies of rats with high or low nurturing mothers, there is a critical period for turning on genes that control anxiety for the rest of life. If in the first 10 days of life you have low nurturing rat mother (the equivalent of the first 6 months of life in a human), the gene never gets turned on and the rat is anxious towards new situations for the rest of its life, unless drugs are administered to alleviate the anxiety. These researchers say there are hundreds of genes affected by nurturance. Similar mechanisms are found in human brains–caregiver behavior matters for turning genes on and off. (Work of Michael Meaney and colleagues; e. g., Meaney, 2001).

The article continues on with a great list of potential issues that may impact either the baby or the mother-child relationship from CIO and explains that the results are difficult, if not impossible to gauge, particularly before adulthood. I’m not being graded for writing this so I’m not going to delve into a critique of the author, since this is an article and not a study, but she is credible (Darcia Narvaez, Ph.D., professor at Notre Dame and her research focus is moral cognition, moral development and moral character education). She acknowledges that this particular article is an opinion piece and not a research article, but all of her sources are cited.

The only study that looked at the effects over time did support the practice in the sense that it did not show that long-term damage would be caused, however it also did not show that NOT using CIO would cause long-term damage (ie: create poor sleeping habits, needy children/adults).

On the other hand, long-term effects of cortisol may not have been conclusively demonstrated, but they were certainly not shown to be safe either and the fact that chronic stress in adults is universally acknowledged to be harmful concerns me. The Psychology Today article poses questions about how CIO may impact brain growth and development overall and I find nothing that refutes these statements since it goes far beyond the claim that behavior and sleep patterns are not impacted when the child is six years old. Also, Project SIESTA seems to be leaning towards the notion that CIO really does not create a more sound sleeper anyway.

In conclusion, CIO is effectively reducing stress in parents, (good), while increasing the stress level in babies, (bad), which does not appear to lead to higher stress levels in older children, (neutral). It also does not seem to lead to deeper sleep or self-soothing, which are two of the main reasons for doing it in the first place. Long term effects are not known as it relates to cortisol spikes and anxiety. There is nothing suggesting that there is any danger, either short or long term, in NOT using CIO so that sounds like the safe bet to me. Go with your gut, mammas. No one actually WANTS to hear a screaming baby.

October 13, 2014 by Allison Lund
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