The baby sleeps: the study reveals why rocking him helps him fall asleep

When the baby cries, to sleep or calm him, parents have an almost automatic reflex: rock him. Whether in the arms, in a swing, in the car, the vibrations and the swinging movement tend to make the little ones fall asleep. In a study published December 1, 2020 in the journal Cell reports, researchers at the Thomas Jefferson University of America have put forward a clue as to why these movements have such a beneficial effect.

A similar mechanism in insects

“Babies love to be lulled to sleep. But the neural mechanisms behind this well-known phenomenon remain a mystery.”explains lead author of the study, neuroscientist Kyunghee Koh, cited by Daily mail. He and his team discovered a parallel with Drosophila, namely fruit flies: when they are subject to vibrations they sleep longer. They were also less sensitive to light pulses that normally wake them easily. Once awakened, they were even more active than usual.

According to the researchers, the vibrations would have allowed them to gain some kind of “sleep credit”. Basically, they acted like they slept more than they needed after falling asleep thanks to the vibrations. “We wanted to establish fruit flies as a model for studying sleep induction mechanisms by mechanical stimulation”, indicates the author of the study.

A form of learning

Scientists explain that flies fell asleep faster and faster the more subjected to vibrations. According to them, this suggests that this process falls within thehabituation, a simple form of learning that is done, as the name suggests, out of habit. “Flies learn over time that vibrations are not a threat, which reduces their response to stimulation that would otherwise make them alert.”explains Kyunghee Koh.

The same phenomenon in children?

For researchers, not being alert when sleeping is essential for falling asleep. Although they have not been able to show that the same mechanism is at work in humans, they point out that the brains of fruit flies and that of humans are similar in shape and function. By cradling a baby, it would also fall asleep easier thanks to the benefits of vibrations. Also, when a baby is rocked regularly, he understands that this is not a dangerous situation but rather a form of pacification.