It’s a frustration many parents know all too well: You’ve finally lulled your crying baby to sleep, so you lay him down in his crib… and the crying starts all over again. Science may have a trick for you.
Holding a crying baby for about five minutes and then sitting for at least another five to eight minutes can soothe and lull the baby to sleep long enough to allow a parent to put the child to bed without waking him upresearchers report on September 13 in current biology.
Some of those same researchers previously showed that holding a crying baby soothes the child and calms a fast heartbeat (Serial number: 04/18/13). For the new study, the team looked at what it takes for a crying baby to fall asleep and stay asleep.
The researchers placed heart rate monitors on 21 crying babies, ranging in age from newborn to 7 months old. The team also took videos of the babies, monitoring their moods as their mothers carried them around a room, sat them in their arms and put them to bed in a crib. That allowed the team to look at how the babies responded to different environments, whether they were crying, fussy, alert or sleepy, beat by beat.
“We test the physiology behind these things that tend to be common knowledge, even though why they work is not well understood,” says Gianluca Esposito, a developmental psychologist at the University of Trento in Italy.
The babies’ heart rates slowed and they stopped crying when their mothers picked them up and held them for five minutes. Some babies even fell asleep. But the researchers also noted that the babies tended to respond to their parents’ movement, whether they were fast asleep or not. For example, a baby’s heart rate sped up if one of the parents turned quickly while she was walking or trying to put the baby to bed.
Sitting seems to smooth the transition from walking to bed, the team observed. Babies cradled on mom’s lap for at least five minutes tended to have slower heart rates and remained asleep once they were placed in the crib. In contrast, the heart rates of six babies whose mothers sat with them for less than five minutes sped up once they went to bed and woke up soon after.
There’s a lot of research on the relationship between babies and mothers, “but I hadn’t seen any work showing that babies responded to mothers’ behaviors while they slept,” says Sarah Berger, a developmental psychologist at Staten Island College in New York. York, who was not part of the study.
Both Berger and Esposito caution that this method is not a magic wand for all babies. It doesn’t rule out sleepless nights, but it’s still something parents can try, Esposito says. And while this study was done with mothers, anyone a baby is comfortable with can do it. “Especially for very, very young children … as long as these caregivers are familiar with the child, it will work,” she says.