'Co-sleeping' gives babies a boost.

Human babies may have evolved to sleep best-and perhaps most safely - when they snooze next to a parent rather than alone in a crib. Evidence for this contention comes from a pilot study directed by James J. McKenna of Pomona College in Claremont, Calif., and Sarah Mosko of the University of California, Irvine, Medical Center,

"When sleeping alone, babies sleep too soon, too long, and too hard," McKenna asserts. "Contact with a parent's body helps to regulate an infant's physiology throughout the night."

McKenna's group studied six mothers and their approximately 3-month-old babies. Each pair alternated between sleeping in the same bed and in adjacent rooms for three consecutive nights.

Infants' heart rates, breathing patterns, and sleep stages largely coincided with those of their mothers during cosleeping nights, McKenna reports. Moms and babies also woke each other briefly throughout the night while sleeping in the same bed. McKenna suggests that this may give co-sleeping babies practice in arousing from prolonged breathing pauses that may, in some cases, result in sudden infant death syndrome (SIDS).

SIDS rates rise sharply in societies where babies usually sleep apart from their parents, he notes. His team plans a larger study to address the effects of sleeping alone on infant breathing and arousal during the night,

Only in the last several hundred years of human evolution have some cultures promoted isolated sleeping arrangements for babies (SN: 8/1/92, p.78). "The push in America for infant independence from parents while sleeping may be out of line with what infants are physiologically capable of," McKenna proposes.