Sleep is essential for various reasons, but recent research from an international team of scientists has uncovered a compelling new reason to prioritize eight hours of sleep per night: it enhances our brain’s ability to learn and retain a new language.

In a new study led by the University of South Australia (UniSA), researchers found that the synchronization of two specific electrical events in the brain during sleep significantly boosts our memory for new vocabulary and complex grammatical structures.

The study involved 35 native English-speaking adults whose brain activity was monitored while they learned a miniature language called Mini Pinyin, which is based on Mandarin and shares grammatical rules with English.

Participants were divided into two groups: one learned Mini Pinyin in the morning and was tested later that evening, while the other group learned the language in the evening and then slept overnight in a laboratory setting where their brain activity was recorded. The following morning, researchers evaluated their language retention.

The results clearly showed that those who had slept performed significantly better than their awake counterparts. Dr. Zachariah Cross, the lead researcher who completed his PhD at UniSA and is now at Northwestern University in Chicago, explains that these sleep-related improvements are linked to the synchronization of slow oscillations and sleep spindles—brainwave patterns that align during NREM sleep, reinforcing our learning process.

“This coupling likely reflects the transfer of learned information from the hippocampus to the cortex, enhancing long-term memory storage,” Dr Cross says. “Post-sleep neural activity showed unique patterns of theta oscillations associated with cognitive control and memory consolidation, suggesting a strong link between sleep-induced brainwave coordination and learning outcomes.”

UniSA researcher Dr Scott Coussens says the study underscores the importance of sleep in learning complex linguistic rules.

“By demonstrating how specific neural processes during sleep support memory consolidation, we provide a new perspective on how sleep disruption impacts language learning,” Dr Coussens says. “Sleep is not just restful; it’s an active, transformative state for the brain.”

The findings could also potentially provide insights for treating individuals with language-related disorders, such as autism spectrum disorder (ASD) and aphasia, who tend to experience more sleep disturbances than the general population.

Studies conducted on both animals and humans demonstrate that slow oscillations enhance neural plasticity – the brain’s capacity to change and adapt in response to experiences and injuries.

“From this perspective, slow oscillations could be increased via methods such as transcranial magnetic stimulation to accelerate aphasia-based speech and language therapy,” Dr Cross says.

Looking ahead, the research team aims to investigate how the dynamics of sleep and wakefulness impact the acquisition of other complex cognitive skills.

“Understanding how the brain works during sleep has implications beyond language learning. It could revolutionize how we approach education, rehabilitation, and cognitive training.”

Journal reference:

1. Zachariah R. Cross, Randolph F. Helfrich, Andrew W. Corcoran, Adam J. O. Dede, Mark J. Kohler, Scott W. Coussens, Lena Zou-Williams, Matthias Schlesewsky, M. Gareth Gaskell, Robert T. Knight and Ina Bornkessel-Schlesewsky. Slow oscillation-spindle coupling predicts sequence-based language learning. Journal of Neuroscience, 2024; DOI: 10.1523/JNEUROSCI.2193-23.2024