Tag Archives | Sleep Training

Earlier in the week, we presented Part 1 of a commentary from Kathleen Kendall-Tackett on a recent study about the long-term effects of controlled-crying for infants. As infant sleep and breastfeeding are so closely tied together, we are so glad to share both Part 1 and Part 2 with our readers.  

By Kathleen Kendall-Tackett, Ph.D., IBCLC, FAPA 

Does Controlled Crying Cause Long-term Change to Cortisol Levels?

Critics of controlled crying have expressed concern that this technique alters infant cortisol level. To address this concern, the authors assessed the children’s cortisol levels at age 6 and found no significant difference between the intervention and control groups. Unfortunately, these findings alone do not mean lack of physiological harm. We need to look at short-term effects.

The question we need to ask is what happens to babies when their mothers do not respond to them? One way this has been studied is by examining the impact of maternal depression on infants. Maternal depression impairs mothers’ ability to respond to their infants’ cues, and raises Infant cortisol levels (Feldman et al., 2009). Even when non-response is temporary, babies still find it stressful. In the still-faced mother paradigm, mothers are asked to not respond to their infants’ cues in a laboratory setting. This research is designed to mimic the effects of maternal depression. The still-faced-mother experiments increase babies’ cortisol levels (Grant et al., 2009).

So why the concern about cortisol? Mainly, it’s this: cortisol is quite toxic to brain cells. If cortisol is elevated for short time, it likely causes no damage. But if cortisol levels are repeatedly elevated because the infants are experiencing long and repeated incidents of being ignored when they cry, it can be a problem. The brain is at its most vulnerable in the first five years, so soaking the developing brain in cortisol is not a good idea (Buss et al., 2012).

The lack of difference between the groups at age 6 does not mean lack of harm. Cortisol levels likely returned to normal in the intervening five years, unless there was ongoing adversity. Unfortunately, cortisol elevated in infancy could have still affected vulnerable brain cells, even if current levels are normal. The authors would need to use more sensitive measures to assess these potential changes.

What About Breastfeeding?

Photo by Alessandro Pinna via Flickr Creative Commons

The final limitation of this study is rather stunning. Price et al. did not measure the effect of infant feeding method on sleep or maternal depression. Yet feeding method has a direct effect on both maternal sleep and postpartum depression, which are the two main factors the authors claim to address with their sleep intervention. Exclusively breastfeeding mothers get more sleep and are less likely to be depressed than their mixed- or formula-feeding counterparts (Doan, Gardiner, Gay, & Lee, 2007; Dorheim, Bondevik, Eberhard-Gran, & Bjorvatn, 2009a, 2009b; Kendall-Tackett, Cong, & Hale, 2011).

Given these findings, isn’t it strange that breastfeeding was not even enquired about? If the study was conducted in a country with low breastfeeding rates, this omission would be somewhat understandable. But it makes no sense coming from a country like Australia, which has one of the highest breastfeeding rates in the world.

Conclusion

So what can we take away from the Price et al. study? Should we recommend the controlled-crying technique to parents? Based on the limitations of this study, I do not recommend this approach. The sample size is small, the follow-up sample is missing the children most likely to be negatively affected, their assessment of the intervention did not account for the Hawthorne/placebo effect, they have not measured dose of the intervention, nor have they accounted for feeding method, which recent research has soundly demonstrated as being related to both variables that are of key interest: maternal fatigue and postpartum depression.

My objections to this approach are not new. When I first encountered the Price et al. study, I remembered a study that this same group of researchers published 10 years ago in the British Medical Journal demonstrating that controlled crying lessened the risk of postpartum depression (Hiscock & Wake, 2002). I was specifically struck by this response from a German physician (Perl, 2002):

“As a German, I am unhappy to find fairly undiluted ideas of militaristic Nazi infant care uncritically repeated by these Australian care providers. The Nazis understood very well the crucial effect of letting young babies cry on their future development and made this a central theme in their child care. As a scientist, I find it hard to believe that all of the results of mother-infant sleep research of the 1990s completely escaped the authors’ notice.” 

In closing, Price et al. stated that organizations, such as the Australian Breastfeeding Association, were unduly negative towards controlled-crying techniques and need to update their recommendations based on more current research. Given recent findings in neuroscience, childhood trauma, breastfeeding, and maternal sleep, which are not accounted for in the Price et al. study, I’d respectfully advise the authors to do the same. I’d further urge healthcare providers who are considering recommending controlled crying to consider the limitations to the current study and alternative approaches that can meet the needs of both mother and baby.

Kathleen Kendall-Tackett, Ph.D., IBCLC, FAPA is a health psychologist and board-certified lactation consultant. She has authored or edited 22 books and more than 320 articles on family violence, postpartum depression, breastfeeding, and women’s health. Dr. Kendall-Tackett is a research associate at the Crimes against Children Research Center at the University of New Hampshire and a clinical associate professor of pediatrics at Texas Tech University School of Medicine in Amarillo, Texas. She is a Fellow of the American Psychological Association, and is president-elect of the APA Division of Trauma Psychology. You can view her website at www.KathleenKendall-Tackett.com

Today, we present Part 1 of a commentary from Kathleen Kendall-Tackett on a recent study about the long-term effects of controlled-crying for infants. As infant sleep and breastfeeding are so closely tied together, we are so glad to share this with our readers. Check back on Thursday for Part 2.

By Kathleen Kendall-Tackett, Ph.D., IBCLC, FAPA 

A recent article in Pediatrics (Price, Wake, Ukoumunne, & Hiscock, 2012) reported on the long-term effects of a controlled-crying intervention for parents of infants 8 to 10 months old. The children were assessed five years post-intervention and showed no apparent harm. The media response to these findings has been overwhelming. Could this be the answer that weary parents have been waiting for? The authors certainly thought so. In fact, they concluded that practitioners could “confidently” recommend this approach.

Before we proceed, let’s step back and consider whether this recommendation is warranted. We must critically evaluate both the current study and where it fits within the larger literature in maternal-child health. In my view, there are a number of serious limitations to this study that call into question whether we should recommend this practice to parents.

Study Limitations

The Cumulative Effect of Childhood Adversities

Context is important to consider when evaluating potential harm caused by a parenting technique. In other words, how many parental missteps does it take for children to show evidence of lasting harm? Fortunately, children are resilient and don’t require perfect parenting. However, chronic bad parenting does harm children and the effects are cumulative (Centers for Disease Control and Prevention, 2010).

So does controlled crying cause infant harm? If it occurs in families with generally warm, responsive, and loving parents, probably not. I am more concerned about the impact of controlled crying when it takes place in high-risk families. A full 31% of the Price et al. original sample was lost to follow-up, most of them “high disadvantage.” In other words, the group most likely to be negatively affected by controlled crying was not in the follow-up study.

Assessing “Dose”: The Chronicity and Severity of the Experience

When assessing potential harm of a practice, it’s also important to consider chronicity and severity. This is a way of factoring in “dose” of an intervention. In terms of infant sleep, we need to know how often controlled crying was used in an average week, how many weeks or months that the parents employed these techniques, and in an average episode how many minutes elapsed before the parents responded to their babies. The longer they used it, the more pronounced the effects.

Information about “dose” was totally absent from the Price et al. study. From their article, we know little about what the parents actually did in either the intervention or control group. Even beyond the research protocol, parents could have implemented a controlled-crying program for themselves. We have no way of knowing. Given the wide range of practices that likely occurred in both the “intervention” and “control” groups, I am again not surprised to see no significant difference between groups.

Was the Intervention Actually Effective, Even in the Short Term?

Another problematic aspect of this study has to do with the research design’s inability to account for the Hawthorne Effect. The Hawthorne Effect was first noted by industrial psychologists who were testing the impact of minute changes in illumination on productivity in factory workers. When they raised the level, productivity increased. When they lowered the level, productivity also increased. In other words, any intervention was described as helpful. It’s basically a placebo effect for behavioral interventions.

The Hawthorne Effect could also be behind the positive results for the controlled-crying intervention. In earlier articles, the authors reported that controlled crying lowered rates of maternal depression and improved infant sleep. Did it? Perhaps it was simply a matter of the mothers having someone to listen to their concerns. A better test would have been to compare it to another intervention (such as educating mothers about the developmental normality of infant waking at 8 to 10 months, and brainstorming about ways the mothers could get more rest and cope with fatigue).

Check back on Thursday for Part 2 of this commentary. 

Kathleen Kendall-Tackett, Ph.D., IBCLC, FAPA is a health psychologist and board-certified lactation consultant. She has authored or edited 22 books and more than 320 articles on family violence, postpartum depression, breastfeeding, and women’s health. Dr. Kendall-Tackett is a research associate at the Crimes against Children Research Center at the University of New Hampshire and a clinical associate professor of pediatrics at Texas Tech University School of Medicine in Amarillo, Texas. She is a Fellow of the American Psychological Association, and is president-elect of the APA Division of Trauma Psychology. You can view her website at www.KathleenKendall-Tackett.com.