Cosleeping - Babies Know Best Place to Sleep

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by Ed Cohen

It's the middle of the night. You're a new mother. Your baby starts crying.

You know from past experience that if you go to her room, pick her up, nurse her, maybe even bring her back to bed, she'll stop crying and fall back to sleep. But you also know better than to do that. Cave in to her demands now, and she'll become overly dependent on you and never sleep through the night. It may be hard, but it's better to show a little resolve now than to hinder her psychological development. She'll cry herself to sleep in a while.

What is wrong with this picture? Everything, according to James J. McKenna, professor of anthropology at Notre Dame and director of Notre Dame's new Center for Behavioral Studies of Mother-Infant Sleep.

Before joining the faculty this past year, McKenna taught at Pomona College in California, where he collaborated with neurologist Sarah Mosko of the University of California, Irvine, School of Medicine for 15 years on a series of experiments looking into what happens physiologically when babies sleep with their mothers instead of alone.

What McKenna and his partner discovered contradicts long-held assumptions about infant care, in particular the notion that parents need to take a hard line against comforting babies at night or bringing them back to bed. In fact, just the opposite appears to be true, they say. Some of their evidence even suggests that some babies who sleep with or near their mothers might gain a measure of insurance against Sudden Infant Death Syndrome (SIDS).

Scientists have long investigated infant sleeping patterns, but the studies have always focused on babies sleeping in isolation, the arrangement most common in Western industrialized nations. For their initial study, McKenna and Mosko recruited a group of Hispanic mothers living around Irvine who normally slept with their babies (the practice is common in Hispanic households) and had them do so in a special sleep laboratory. Both mother and child were hooked to equipment that monitored breathing, heart rates, body temperature, brain waves, time spent nursing, and other activity and variables.

The researchers discovered that infants who routinely sleep with their mothers breast-feed twice as often and for three times longer than babies left in a separate room at night. Extra breast- feeding is considered beneficial because breast milk provides antibodies to fight disease. Breast- feeding also has been tied to more rapid and complete cognitive development. And, contrary to popular expectations, mothers who routinely bring their babies to bed get more sleep than those who try to keep their offspring one or more rooms away.

But the advantages of "co-sleeping" go way beyond nighttime breast-feeding on demand or extra shuteye, McKenna argues. It's his belief that the arrangement is nothing less than what nature intended. Or, put another way, what evolution has built into our biology.

Mothers have been sleeping with their babies to keep them warm and safe from predators since at least the time families ate mastodon for dinner. As a result, McKenna argues, all babies are born physiologically "expecting" a steady stream of sensations — specifically, the touches, smells, sounds, movements and warmth they receive only from being in close proximity, day and night, to their mothers. When these sensations cease because one has been deposited in a separate bedroom down the hall, a predicable response occurs: crying.

"It's natural and expectable and appropriate for a babies and children to protest sleep isolation from their parents," says McKenna. "(Crying) is a loving gesture, and it's a healthful gesture that children make. It isn't a sign of pathology at all."

There's another good reason why infants instinctively desire round-the-clock closeness: Humans are born with just 25 percent of their adult brain volume, making us the least neurologically mature of any primate species at birth. In a very real way, we are all born prematurely.

McKenna's theories are relevant to SIDS because infants sleeping next to their mothers have been found to spend less time in the deepest stages of sleep than babies sleeping alone. They also are naturally nudged at least partially awake more often at night by their parents moving in their sleep. In some cases, SIDS is believed to result from babies experiencing apnea, a temporary suspension of breathing during sleep. It could be that certain babies die because they're too deep asleep and have too little experience being roused from sleep, the result of their being deposited in a quiet, empty bedroom for sleeping period after sleeping period.

McKenna suspects that the physiological changes babies experience sleeping next to their mothers, combined with the periodic breast feeding that naturally occurs, can offer some protection from SIDS. He notes that in Japan, which has the world's lowest incidence of SIDS, babies routinely share their parents' bed. Co-sleeping is, in fact, the preferred arrangement for 90 percent of the world's population.

McKenna says the idea that co-sleeping can stunt a child's psychological development is not based on research. In fact, the few studies that have looked at the arrangement's developmental effects suggest the opposite. A study of military families, in which co-sleeping is common because fathers (and, nowadays, mothers) are often away from home for extended periods, found that children who had coslept as babies received higher evaluations of their comportment in school and exhibited fewer psychiatric problems. Another study found that by college age, co-sleepers appear to be better adjusted and more satisfied with their sexual identities and behavior than their counterparts.

One enduring fear about co-sleeping is that accidental suffocation can result from a parent rolling over onto an infant. McKenna says accidental suffocation is extremely unlikely, except in cases where a mother is desensitized from taking drugs or alcohol, or where a mattress is too soft or the bed is falling apart. Adults will naturally avoid rolling onto a baby, McKenna says, the same way they automatically keep from rolling out of bed. In fact, the researcher hopes to lay that fear to rest this fall with experiments in the new Notre Dame lab in which students will be given a doll to sleep with while their movements are recorded using infrared cameras.

So how did it become the norm in the industrialized West for mothers to sleep apart from their babies? McKenna's research points to several possible historical origins. In 17th century Europe, laws were enacted threatening parents with jail if they were caught in bed with their infants. The measures were aimed at preventing infanticide — a serious problem among the extremely poor at the time. When they were unable to provide food for more than one child at a time, some parents falsely claimed to have accidentally rolled over them, killing the infants while sleeping. "The important point," McKenna emphasizes, "is that it was not accidental suffocation that induced such laws but purposeful suffocation."

Despite the many benefits he sees in co-sleeping, McKenna stops short of declaring it essential for healthy child care. People who, for whatever reason, don't feel comfortable doing it, shouldn't, he says. He merely hopes the practice comes to be viewed as an option that parents can feel good about choosing.

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