Mother-infant bedsharing is associated with an increase in infant heart rate.

OBJECTIVES: We hypothesized that mother-infant bed sharing, compared to solitary sleeping, would be associated with higher infant heart rates. The objective was to compare infant heart rates between the 2 environments and, secondarily, to test for relationships between heart rate and other, previously reported, differences in the same infants.
DESIGN: Heart rate was measured in 15 infants over a bed-sharing night and a solitary-sleeping night. Eight of the 15 infants routinely bed shared with the mother at home; the other 7 routinely slept in a room alone.
SETTING: The Sleep Disorders Center, University of California, Irvine Medical Center. PARTICIPANTS: Fifteen mother-infant pairs who met criteria for routinely bed sharing or sleeping solitarily. All were healthy, and infants were more than 38 weeks gestation at birth and 11 to 15 weeks old at the time of the study.
INTERVENTIONS: None.
RESULTS: Analysis of variance indicated that, irrespective of routine sleeping condition, heart rate was lower during solitary sleeping than during bed sharing in all sleep stages. Significant regressions were found with infant temperature. Heart-rate variability was higher during solitary sleeping than during bed sharing (both routine groups) in stages 1 and 2 and rapid eye movement sleep, but only stages 1 and 2 sleep effects were independent of basal heart rate.
CONCLUSIONS: Infant heart rate is affected by the mother's presence in the sleep environment. The increase in sympathetic activity in stages 3 and 4 and rapid eye movement sleep might be partly explained by differences in thermoregulation between bed-sharing and solitary-sleeping environments. These results support the notion that sensory differences between bed-sharing and solitary-sleeping environments account for some of the physiologic differences between infant sleep in the 2 sleeping conditions.