Sleeping Through the Night: The Consolidation of Self-regulated Sleep Across the First Year of Life

The recent paper by Henderson et al does not appear to consider the regulatory and developmental aspects of breastfeeding for infants, and the contribution of breastfeeding to mother-infant synchrony and responsiveness. With the study participant families totalling seventy-five and the majority described as ‘white New Zealand middle-socioeconomic status volunteers’, whose ‘socially meaningful’ definitions for sleeping through the night are being described? What are ‘typical family’ sleep schedules?

When interventions are suggested to target the ‘management’ of infant sleep in the first three months of life, and it is also suggested that starting at one month of age is appropriate, I wonder what this means. Is this a hint of a controlled crying approach and where do the researchers see developmentally appropriate cue based infant feeding fitting in here – both for breastfed and for bottle-fed-formula-fed infants.

What about the importance of breastfeeding establishment over the first six to eight weeks after birth? Certainly for breastfeeding infants, displaying a ‘normal’ range of breastfeeding behaviours which include frequent feeding periods,(1) controlled sleep interventions are likely to interfere negatively with breastfeeding establishment. Kent et al found that breastfeeds at night made an important contribution to total milk intake (2) so sleep interventions that involve ignoring infant feeding cues may also impact negatively on growth and development.

The Australian Association for Infant Mental Health (AAIMH, 2002) have expressed concern about controlled crying techniques, which they describe as being inconsistent with infant optimal emotional and psychological health, with a potential for unintended negative consequences.(3) AAIMH also point out that Western lifestyle demands and some ‘expert’ advice has led to an expectation that all infants and young children should sleep through the night from the early months or even weeks.

As the AAIMH conclude in their statement about controlled crying interventions – “It is normal and healthy for infants and young children not to sleep through the night and to need attention from parents”.

1. Kent, J.C., Mitoulos, L.R., Cregan, M.D., Ramsay, D.T., Doherty, D.A., & Hartmann, P.E. (2006). Volume and frequency of breastfeedings and fat content of breast milk throughout the day. Pediatrics, 117, (3), e387-e395.

2. Ibid

3. http://www.earlychildhoodaustralia.org.au/Controled%20Crying.pdf

Conflict of Interest:

None declared

To the Editor

I am dismayed by the publication of the study of Henderson et al which ostensibly documents the normal patterns of sleep in infants in the first year of life. The population studied was non random, self selected and not representative of the varied ethnic, cultural, socioeconomic diversity of a normal population. Thus, just on these grounds this inevitable selection bias precludes any conclusions.

Even more importantly, no information was provided as to the feeding patterns of the infants: what percentage if any were breastfed?, in the breastfed infants to what degree was supplementary commercial formula added, at what age were complementary foods introduced and how (bottle, spoon,), what sleeping arrangements were followed (separate rooms, close proximity or co-sleeping). The absence of information regarding these variables which impact on the sleeping pattern of infants similarly invalidates the presentation of the authors results as a description of the natural history of sleep and surely the results cannot serve as a basis for the guidance of parents as to what are normal infant care practices.

Furthermore, while the fact that the authors have no medical background may explain their lack of including such basic clinical data in the their study design, it does not explain the absence of even mentioning these serious limitations in the discussion section. This in of itself raises serious question as to the review process that the study underwent.

Arthur I Eidelman MD FAAP FABM Department of Pediatrics Shaare Zedek Medical Center Jerusalem Israel 91031

Conflict of Interest:

None declared

On the front page of the New York Times of 26.10.10 Dr. Robert W. Block, president-elect of the American Academy of Pediatrics makes the statement “The old adage that breast-feeding is a child’s first immunization really is true. So we need to do everything we can to remove the barriers that make it difficult.”1 It is particularly frustrating, then, that in the AAP’s journal Pediatrics one of these barriers to breastfeeding is reinforced by the online publication in the same week of a research study on infant sleep2. The publication of this paper perpetuates the western cultural notion that infants can and should sleep “through the night” from a very young age. However, encouraging young babies to sleep “through the night” is one of the most effective means of killing a mother’s ability to sustain breastfeeding and denies a young infant a third of its daily nutrient intake. Regular nighttime suckling is crucial for successful lactation3 and is an important modulator of infant sleep architecture and arousal patterns. How can a research paper published in 2010 on infant sleep development possibly overlook or ignore the relevance of night-time breastfeeding? How could the reviewers overlook or ignore such a fundamental omission?

By passing peer review the publication of this paper highlights a generic problem in the field of infant sleep research: that cultural ideologies from 50 or so years ago remain embedded within a research paradigm, untouched and unmoved by recent clinical scientific insights about the health and development of normal infants. This paradigm assumes that solitary sleeping, formula-fed infants are appropriate subjects from which ‘normal’ infant sleep measurements should be derived. Surely the recent re-calibration and standardization of infant growth charts around the norm of the breastfed infant4 would signal to related disciplines that feeding method should be an inherent component of defining any form of developmental standards?

In western industrialized nations 70 to 90% of mothers initiate breastfeeding. Pediatricians advising those mothers look to Pediatrics and the AAP to provide research evidence relevant to their practice within the US and beyond. If these Pediatricians, their clinical colleagues and allied health professionals advise women based on the published results of Henderson et al’s paper they will undermine the hard won improvements in breastfeeding rates over the past two decades in one fell swoop. The researchers state, without any acknowledgement of the limitations of their study, that: “Our longitudinal study provides a reliable empirical foundation for advice about infant sleep development and provides a context for clinicians to discuss sleep issues with parents” (p. 1066). Sadly, it does not. It could do, if only the authors differentiated amongst their sample as to how their infant subjects were feeding and where they were sleeping, but this critical information is missing. It is difficult to know if Henderson et al. assume that feeding method is simply not important enough to consider as a variable affecting the infant sleep parameters they measured, but we should not allow such an assumption to pass by unchallenged. Infant feeding mode cannot be ignored in any discussion of how infants sleep, or more pejoratively, how infants should sleep, or how parents should “plan” for their sleep.

Also missing in the authors’ discussion is any mention of whether it is safe for infants to experience sleep environments (or sleep training methods) that artificially accelerate infant sleep maturity or encourage self-soothing. The arousal mechanism is the primary means by which infants defend themselves against potentially fatal breathing or cardiac perturbations. Encouraging early sleep consolidation may be placing arousal-deficient infants at increased risk of sudden and unexpected death5, 6, while self-soothing may undermine parental vigilance and encourage parents to leave their infants unattended for lengthy periods.

While the authors do not directly promote early sleep training their conclusion and limited discussion (which makes no mention of the breastfeeding dyad), has already been used in the media7 to justify the argument that sleeping through the night from an early age is a part of “normal” healthy, desirable infant sleep development. “When should an infant sleep through the night? Sooner than you think”, read the headline in the Chicago Tribune following the publication of the Henderson et al paper. The article states: “A new study shows that infants have the ability to sleep "through the night" by 3 months of age” with no comments from the authors as to why these findings should not be taken to mean that this is necessarily good for all or even most infants, or that not all infants and families are the same, or how the presence or absence of breastfeeding changes what can and should be expected. Instead the readers are left with this comment; “….the authors of the paper, from New Zealand, say this proves that the little devils, er, infants, can be taught to sleep through the night using the 10 p.m. to 6 a.m. target by 4 months of age. After the infant is 1 month old, the article reads, “parents should begin planning, and working with the pediatrician, on getting the infant to sleep through the night, they say.” At one month old?

This comment reflects no more than a personal social judgment, and a dangerous one at that, having little to do with evidence-based principles as to what is in the infant’s best interest. Multiple home, hospital and laboratory studies are now available that have systematically examined breastfeeding infants sleeping alone and with their mothers and what is clear is that very few infants ever make it through an evening without multiple awakenings and many are associated with breastfeeds8.

The ‘sleep through the night’ cultural ideal continues to have other unwelcomed consequences: it promotes the view that infants and parents begin life as adversaries as it asks of infants something they are not biologically equipped to do given their inherent nutritional and emotional needs. This ideology continues to sustain a “bedtime battle” mentality that is pervasive in western cultures. Not only does this milieu lead to disappointed if not frustrated parents where nobody achieves a positive outcome, but to inappropriate moral judgments leveled against infants (and parents) who do not “measure up”. It needlessly sustains a way of thinking that promotes the very infant sleep problems western pediatric sleep researchers are asked to solve.

The importance of breastfeeding and the impressive recent shift from artificial formula back to breast-milk experienced by western, industrialized cultures has yet to be reflected in western pediatric infant sleep research protocols, as demonstrated by the paper of Henderson et al. According to figures published by the CDC at least 75% of infants in the USA are initially breastfed. Their parents deserve to receive pediatric advice on their infant’s sleep that reflects how infant feeding and sleeping are functionally intertwined, and how altering one will affect the other. Any study that ignores the relationship of infant sleeping with feeding methods must be regarded as essentially flawed.

James J. McKenna, Ph.D Edmund P. Joyce C.S.C. Chaired Professor of Anthropology Director, Mother-Infant Behavioral Sleep Laboratory Fellow, American Association for the Advancement of Science University of Notre Dame, Notre Dame, Indiana 46556 USA

Helen L Ball Ph.D Professor of Anthropology Director, Parent-Infant Sleep Lab Fellow, Wolfson Research Institute Durham University, Durham, DH1 3LE, UK

1. Kocienciewski D Acne cream? Tax sheltered. Breastmilk? No. New York Times October 26th 2010 2. Henderson JMT, France KG, Owens JL, Blampied NM. Sleeping Through the Night: The Consolidation of self regulated sleep across the first year of life. Pediatrics. 2010 126(5):e1081-1087 3. Elias, M. F., N. A. Nicolson, et al. (1986). Sleep/wake patterns of breast-fed infants in the first 2 years of life. Pediatrics 77(3): 322-329. 4. Wright C, Growth charts for babies. BMJ 2005 330:1399-400 5. Mosko S, Richard C, McKenna J. Infant arousals during mother-infant bed sharing: Implications for infant sleep and sudden infant death syndrome research. Pediatrics 1997; 100: 841-49. 6. Mosko S, Richard C, McKenna J. Infant sleep architecture during bedsharing and possible implications for SIDS. Sleep 1996; 19:677-84. 7. Roan S “When should an infant sleep through the night? Sooner than you think”. Chicago Tribune October 24, 2010. Health Section. 8. McKenna JJ, Ball HL, Gettler LT. Mother-infant co-sleeping, breastfeeding and sudden infant death syndrome (SIDS): What biological anthropology has discovered about normal infant sleep and pediatric sleep medicine. Yearb Phys Anthropol 2007; 50: 133-61.

Conflict of Interest:

None declared

Very interesting article, and one that leads to a big question: how were these infants fed?

My understanding of the evidence is that newborns who sleep too deeply are at increased risk for SIDS. How is a 2-month old baby sleeping for a 5 to 8 hour stretch a healthy thing?

I can't imagine that many of these infants were exclusively breastfed, which is the international recommendation for the first 6 months of life.

sincerely, Nikki Lee RN, BSN, MS, Mother of 2, IBCLC, CCE, CIMI

Conflict of Interest:

None declared