The effect of sleep on the human brain ‘suddenly changes’ in childhood from learning and memory support to maintenance and repair, study shows
- American researchers studied brain and sleep data from children aged 0-15 years
- They found that sleep function shifts around the age of two and a half
- This is an age at which several major brain transformations are known to occur
As children grow, the effect sleep has on the brain changes from memory support and learning to maintenance and recovery, a study finds.
American experts found that the function shift occurs around the age of two and a half years – a time when several major brain transformations were previously known to occur.
Most animals need sleep to repair stress-induced damage and recognize neural patterns, which are essential for stimulating learning and memory skills.
As children grow, the effect sleep has on the brain changes from memory support and learning to maintenance and recovery, a study finds. US experts found that the function shift occurs around two and a half years of age – a time when several major brain transformations were previously known to occur
“The ubiquity of sleep during development and throughout the animal kingdom suggests that it is a biological process necessary for survival,” said author Junyu Cao of the University of Texas at Austin.
“Although we spend about a third of our lives asleep, its explicit physiological and evolutionary function remains unclear, with a host of hypotheses.”
In their study, Professor Cao and colleagues analyzed sleep data sets – from children between 0 and 15 years old – using models that focused on brain metabolism, volume and amount of time spent in REM sleep.
REM – or ‘rapid eye movement’ – is one of five stages of sleep that occur multiple times a night and is when there is dreaming.
“We have created a new mechanistic framework to understand and predict how sleep changes,” explains Professor Cao.
“Because data is rarely analyzed in a way that relates it to mathematical models or quantitative predictions, conclusions about the function of sleep continued to evolve slowly,” she added.
Neural reorganization, an important part of learning and memory, occurs before children reach the age of two and a half, the researchers found.
After this point, the brain appears to stop reorganizing and instead focus on protecting and repairing neural networks.
According to the team, the change in sleep function was not gradual, but rather like ‘water turning into ice’.
“Our findings reveal an abrupt transition, between two and three years in humans,” said paper author Van Savage of the University of California, Los Angeles.
“Specifically, our results show that differences in sleep between animal groups and during late ontogeny (at two or three years, in humans) are mainly due to sleep functioning for recovery or clearance.” ‘
“Sleep changes during early ontogeny (before two or three years) primarily support neural reorganization and learning.”
Neuroplastic reorganization, the brain’s ability to learn by altering structure and function, occurred during REM sleep stages rather than non-REM sleep stages, the researchers also found.
The researchers hope to investigate the sleep function change in animals with shorter developmental periods, where it occurs earlier and may even occur before birth.
The full findings of the study have been published in the journal Science Advances.
CAN YOU LEARN DURING YOUR NAP?
It’s the perfect shortcut to play a language tape or revision recording at night while you sleep.
But those who are desperate for the information to come in while snoozing may be disappointed.
Scientists have previously found that the brain does record what it hear during REM sleep – the time mostly spent dreaming, usually in the morning before we wake up.
Running a tape overnight is likely counterproductive, as information obtained in deep sleep can be completely lost.
French researchers found that the sound played during certain parts of deep sleep can make learning information more difficult when you wake up than if you had never heard it before.
That’s because the brain is currently in the process of erasing memories, and the new knowledge is being dumped along with them.
In a study published in August 2017 by experts at PSL Research University in Paris, researchers tested sleep learning by playing 20 participants white noise, which contained sound patterns.
The sounds heard during the REM sleep phase (rapid eye movement) were remembered by these people when they woke up.
They found it easier to identify the white noise with repeated sounds because they had heard it while they were sleeping.
But the sound played while people were fast asleep, which makes up nearly a third of our sleep, has been forgotten.