Researchers discover why disturbed sleep hampers learning

It seems obvious that a poor night’s sleep would hamper a person’s ability to learn new skills or information, but now researchers from the University of Zurich and the Swiss Federal Institute of Technology have for the first time scientifically established a causal link between the two.
While it had long been hypothesized that deep sleep was essential for restoring the brain’s ability to learn efficiently and that a poor night of slumber can negatively impact an individual’s overall performance, the scientists set out to examine how each altered normal brain function.
As they reported in a study published this week in the journal Nature Communications, they used a technique which enabled them to cause one region of the subject’s brain (the motor cortex) to experience the effects of sleep deprivation without disturbing his or her overall sleep pattern.
The motor cortex, as Medical News Today explained, is the part of the brain responsible for the development and control of motor skills, while the deep sleep phase (also known as slow-wave sleep) plays a vital role in the formation of new memories and the ability of the brain to recover after a day of activity.
To investigate how the motor cortex is affected by sleep deprivation, the researchers “developed a method that lets us reduce the sleep depth in a certain part of the brain and therefore prove the causal connection between deep sleep and learning efficiency,” Reto Huber, a professor of child and adolescent psychiatry at the University of Zurich, explained in a statement.

Findings could be used to help treat diseases like epilepsy

Huber’s team recruited six women and seven men and asked them to learn and perform a trio of different sequences of finger movement following both a good night’s sleep and a night in which their slow-wave slumber and been disturbed. By studying the subjects on the first night, the team knew which parts of the brain to disrupt to hamper learning the sequences on the second.
The subjects were not aware that part of their motor cortices was being disrupted, according to the researchers; to them, the quality of sleep seemed to be about the same. However, their overall performance when it came to learning the finger movement declined during these trials.
Following a good night of sleep, the subjects were able to easily learn the sequences at first, then experienced a decline in overall performance as the day progressed. After a night of poor quality sleep, however, learning issues surfaced almost immediately, the study authors noted. In fact, the first-morning performance following a poor night of sleep was about as bad as the final one from the previous evening – the sleep had little to no restorative effect on the brain.
The reason for this phenomenon, Medical News Today explained, is that motor cortex neurons were unable to “rest” when manipulated as they would during a normal night of sleep. Over the course of a normal day, the brain’s synapses are excited by the various stimuli that we encounter, but their activity normalizes while we sleep. If they remain excited for too long, the website said, it prevents us from learning new things.
“In the strongly excited region of the brain, learning efficiency was saturated and could no longer be changed, which inhibited the learning of motor skills,” co-author Nicole Wenderoth said in a statement. Huber added that the researchers hope to use this information to study ailments which manifest during sleep (such as epilepsy). “Using the new method,” he explained, “we hope to be able to manipulate those specific brain regions that are directly connected with the disease.”
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