However, when the mothers tried to put their sleepy babies back to bed, more than one-third of the participants became alert again within 20 seconds. The team found all babies produced physiological responses, including changes in heart rate, that can wake them the second their bodies detach from their mothers.
The study also determined that if the infants were asleep for a longer period before being laid down, they were less likely to awaken when being put back into the cot.
“Even as a mother of four, I was very surprised to see the result. I thought babies waking up during a laydown was related to how they’re put on the bed, such as their posture, or the gentleness of the movement,” Kuroda said.
“But our experiment did not support these general assumptions.”
While the experiment involved only mothers, Kuroda expects the effects are likely to be similar in any caregiver.
Based on their findings, the team has proposed a method for soothing and promoting sleep in crying infants. They recommend that parents:
- hold their crying infant and walk with them for five minutes
- then sit and hold the infant for a further five to eight minutes, before putting them back to bed.
The protocol, unlike other popular sleep training approaches such as letting infants cry until they tire themselves out, aims to provide an immediate solution. Whether it can improve infants’ sleep in the long-term requires further research, Kuroda added.
“For many, we intuitively parent and listen to other people’s advice on parenting without testing the methods with rigorous science. But we need science to understand a baby’s behaviors, because they’re much more complex and diverse than we thought.”
This evidence-based strategy is presented in a paper published September 13 in the peer-reviewed scientific journal Current Biology.