New York - Very premature infants sleep more deeply when they're placed on their fronts rather than on their backs.
In the prone position they have fewer arousals and more episodes when they stop breathing briefly, which may increase their risk of sudden infant death syndrome (Sids), UK investigators report.
These findings emphasise the importance of recommending supine sleeping when preterm infants - who are already at increased risk of Sids - leave the neonatal intensive care unit.
Dr Anne Greenough, of King's College Hospital, London, and colleagues studied 24 infants born at an average gestational age of 28 weeks, and report their findings in the medical journal Pediatrics
Before the infants left the NICU, they were observed for three hours in the supine position and three hours in the prone position.
The team monitored the infants for nasal airflow, chest and abdominal movement, limb movement, heart rhythm, and oxygen levels in their blood. The researchers also recorded sleep duration and the number and type of non-breathing episodes, arousals and awakenings.
The infants slept significantly longer in the prone position, spent significantly less time in active sleep and more time in quiet sleep.
In the supine position, the infants had significantly more awakenings and more arousals per hour, along with fewer episodes of not breathing, or apnea.
"Arousal from sleep is an important survival response to life-threatening events, such as prolonged apnea," Greenough's team points out.
"By arousing from sleep, ventilation is increased and a behavioural response evoked," they note. "Any impairment in arousal could then contribute to Sids."
SOURCE: Pediatrics, July 2006.