TOKYO -- A baby that just won't stop crying is a nightmare for anyone involved in child care, or simply within earshot. To ease stress, an international team including the Japanese government-backed Riken research institute announced it has scientifically confirmed the best way to put a baby to sleep.
Babies are known to stop crying and relax when a caregiver carries them while walking around. The team figured out the mechanism behind this effect, and announced their findings in 2013. But as babies can sometimes wake up and start crying again, researchers had been looking for a more reliable method.
The team tested 21 pairs of babies aged 7 months or younger and their mothers. The subjects were drawn from a range of nationalities and races, including those from Japan and Italy. In the experiment, when their babies cried loudly, moms randomly combined four actions -- carrying them on a walk, sitting while holding them, putting them to bed, and rocking them in a stroller -- about every 30 seconds. Researchers then looked at the heart rate of the babies and how much they were crying.
Results showed that the most effective way to put a baby to sleep was to carry them and walk around for five minutes, sit and wait for five to eight minutes, then put them to bed. Even if the baby is asleep, they notice when they have been separated from their caregiver. By sitting down to rest after the baby stops crying, they can apparently be put into a deep sleep.
The team's findings were published in the digital edition of the American scientific journal Current Biology on Sept. 14. Based on the results of their study, the team will work on developing apps and devices that predict a baby's condition and give advice on what to do.
Riken researcher and team leader Kumi Kuroda joined the experiment with her two children. She says the trick was to hold the baby close to her body, and walk at a constant speed on a flat surface. She explained, "Even though child care is something I'm familiar with, there are things I can't understand just based on my own experience. Scientifically quantifying that leads to support (for caregivers)."
(Japanese original by Yui Shuzo, Science & Environment News Department)