Healthy Infant Sleep

Healthy Infant Sleep

by Dr. James J. McKenna, Professor of Anthropology and the Director of the Center for Behavioral Studies of Mother-Infant Sleep, Notre Dame University

Excerpt from: Breastfeeding Abstracts, February 1993, Volume 12, Number 3

Mother-infant co-sleeping often accompanies nighttime breast-feeding. New research suggests that co-sleeping affects infant physiology and patterns of arousal, raising questions about currently accepted norms for “healthy” infant sleep.

Judging from the infant’s biology and evolutionary history, proximity to parental sounds, smells, gases, heat, and movement during the night is precisely what the human infant’s developing system “expects,” since these stimuli were reliably present throughout the evolution of the infant’s sleep physiology. The human infant is born with only 25 percent of its adult brain volume, is the least neurologically mature primate at birth, develops the most slowly, and while at birth is prepared to adapt, is not yet adapted. In our enthusiasm to push for infant independence (a recent cultural value), I sometimes think we forget that the infant’s biology cannot change quite so quickly as can cultural child care patterns.

An infant sleeping for long periods in social isolation from parents constitutes an extremely recent cultural experiment, the biological and psychological consequences of which have never been evaluated. Most Americans assume that solitary sleep is “normal,” the healthiest and safest form of infant sleep. Psychologists as well as parents assume that this practice promotes infantile physiological and social autonomy. Recent studies challenge the validity of these assumptions and provide many reasons for postulating potential benefits to infants sleeping in close proximity to their parents – benefits which would not seem likely with solitary sleeping. Current clinical models of the development of “normal” infant sleep are based exclusively on studies of solitary sleeping infants. Since infant-parent co-sleeping represents a species-wide pattern, and is practiced by the vast majority of contemporary peoples, the accepted clinical model of the “ontogeny” of infant sleep is probably not accurate, but rather reflects only how infants sleep under solitary conditions. I wonder whether our cultural preferences as to how we want infants to sleep push some infants beyond their adaptive limits.

To explore this possibility further, Dr. Sarah Mosko and I are studying the physiological effects of mothers and infants sleeping apart and together (same bed) over consecutive nights in a sleep lab. Our two pilot studies conducted at the University of California, Irvine School of Medicine, showed that the sleep, breathing, and arousal patterns of co-sleeping mothers and infants are entwined in potentially important ways. Solitary sleeping infants have a very different experience than social sleeping infants – although we do not know yet what our data mean.

Funded by the National Institutes of Child Health and Human Developments, this research will help us to evaluate the idea that infant-parent co-sleeping may change the physiological status of the infant in ways that, theoretically, could help some (but not all) SIDS-prone infants resist a SIDS event (McKenna 1986: McKenna et al. 1991: McKenna et al., in press). One of the suspected deficits involved in some SIDS deaths is the apparent inability of the infant to arouse to reinitiate breathing during a prolonged breathing pause. Our preliminary studies show that mothers induce small transient arousals in their co-sleeping infants at times in their sleep when, had the infant been sleeping alone, arousal might not have occurred. We have suggested that perhaps co-sleeping provides the infant with practice in arousing. Before we can draw any conclusions, more work is needed.

Regardless of what our own research will reveal, there already exists enough scientific information to justify rethinking the assumptions underlying current infant sleep research, as well as pediatric recommendations as to where and how all infants should sleep. Especially needed are new studies which begin with the assumption that infant-parent co-sleeping is the normative pattern for the human species – and that our own recent departure from this universal pattern could have some negative effects on infants and children. We need to determine if unrealistic parental expectations, rather than infant pathology, play a role in creating parent-infant sleep struggles – one of the most ubiquitous pediatric problems in the country. It may well be that it is not in the biological best interest of all infants to sleep through the night, in a solitary environment, as early in life as we may wish, even though it is more convenient if they did so.

Co-sleeping is often discussed as if it were a discrete, all-or-nothing proposition (i.e., should baby sleep with parents?). Many parents fail to realize that infants sleeping in proximity alongside their bed, or with a caregiver in a rocking chair, or next to a parent on a couch, in a different room other than a bedroom, or in their caregiver’s arms all constitute forms of infant co-sleeping. I studied the location of infants and parents in their homes between 6:00PM and 6:00AM and found more infant-parent contact than parents describe.

I prefer to conceptualize infant sleep arrangements in terms of a continuum ranging from same-bed contact to the point where infant-parent sensory exchanges are eliminated altogether, as, for example, infants sleeping alone in a distant room with the door closed. Nowadays, one-way monitors often broadcast infant stirrings to parents in these situations, compensating for the loss of sensory proximity.

I am amused by this baby monitor phenomenon, primarily because we Americans seem to have gotten it all backward. Rather than parents monitoring the infant, a great number of developmental studies suggest that it should be the other way around, with the infant processing parental stirrings (especially breathing sounds and vocalizations). Infant sleep, heart rate, breathing, and arousal levels are all affected by such stimuli, probably in adaptive ways to facilitate development and to maximize adjustment to environmental perturbations (Chisholm 1986). At the very least, monitors should be broadcasting sound in both directions!

Given the human infant’s evolutionary past, where even brief separations from the parent could mean certain death, we might want to question why infants protest sleep isolation. They may be acting adaptively, rather than pathologically. Perhaps these infant “signalers,” as Tom Anders calls them, have unique needs and require parental contact more than do some other infants, who fail to protest. It’s worth considering.

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Schedulers vs. Huggers

Schedulers vs. Huggers

Reproduced from the Guardian: Family Features Dec 13, 2008

When a baby is small, particularly if it’s the first one, parents tend to verge on the doctrinaire regarding the best parenting approach, falling into two camps: strict routine (the schedulers) or infant-led (the huggers).

Holidaying friends with conflicting methods risk lifelong schism, yet hardly anyone bases their view on science. So what do the studies show?

The most definitive was done recently by British and Danish psychologists. They identified a sample of pregnant London mothers who intended to follow a parent-led, scheduled routine. For example, many hoped to get the baby into a cot as soon as possible, feeding and sleeping to a timetable, and planning to delay responses to crying, to teach self-soothing.

By contrast, another sample was also studied, who adopted the hugger approach. They would be keeping the baby in the bed rather than a cot, and feeding on demand. There was also a sample of Copenhagen mothers who fell between these two nurturing plans. The samples were followed until three months of age. Compared with the hugger mothers, the schedulers spent half as much time holding their babies and were four times less likely to make contact with it when fussing or crying. Twice as many schedulers had given up breastfeeding when the baby reached three months of age (85% v 37%). The results for the Copenhagen mothers generally fell between the two, though veering towards the huggers.

The consequences of this differing care were considerable. At all three ages when studied (10 days, five weeks and three months), the babies with scheduler mothers spent 50% more time fussing or crying. For example, at five weeks, the scheduler babies fussed/cried for 121 minutes of the 24 hours, compared with 82 minutes for the hugger babies.

If you take the view that persistent fussing and crying are undesirable for a baby – because they are signs of distress – then this is evidence that the scheduler regime is bad for a baby’s wellbeing. If the method really does cause a 50% greater prevalence of fussing and crying in three-month-olds, innumerable other studies suggest that such distress often presages emotional insecurity, hyperactivity and conduct disorders in later childhood.

However, if scheduling was bad news for the babies, it was not all bad for their mothers. At three months (although not before that age), scheduler babies were more likely to sleep for five or more hours a night without waking or crying – significantly longer than among the huggers. However, this scheduling benefit may have been illusory. If the scheduler babies were sleeping in cots in another room, how confident could their mothers be that their babies had not woken up? Nearly all the hugger babies (84%) were in bed with their mothers and waking or crying would rarely be missed. The researchers concluded that the scheduled babies were probably waking more than their mothers realised, casting doubt on the finding.

It is pathetic that this is the only serious study of the question. We also need to know what the consequences of different regimes are in later life. For there is good evidence that as the child gets older, scheduling is increasingly effective for creating good sleep. So it may be helpful to encourage such “self-regulation” when the child is one or two, not at all good to do so at three months. But it is also possible that children who keep getting into the parental bed until middle childhood are ultimately more secure and creative. Why is this issue not at the top of the psychology profession’s research agenda?

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