Time2Learn, then time to sleep: evening practice may help language stick
When is the best time to practice a foreign language so your brain can cement it during sleep? Early findings by Northeastern researchers suggest studying in the evening may give learners an edge.
Imagine this: you spend weeks studying a foreign language by conjugating verb tenses, wrestling with unique spelling and wondering what in the world makes “turnip” feminine in Italian but masculine in Spanish. But then when it comes time to put all that work into practice, you draw a blank. The anomia kicks in. The right word escapes you. And you can’t remember a single thing.
It’s a familiar struggle. But it’s also a distinctly grown-up one. Children have a knack for soaking up new languages around them without the need for flashcards or grammar drills. For adults, it’s usually a matter of hitting the books.
But what’s the secret behind making all that learning stick?
For Zhenghan Qi, a communication sciences and disorders professor at Northeastern University Bouvé College of Health Sciences the answer may hinge on what happens long after the books close — sleep.
“Sleep is an active part of learning and memory,” Qi said, referring to previous research that provides solid evidence for this idea.
While a memory might form during the day, there’s no guarantee it will take root, clinical sleep educator Lauri Leadley told Northeastern Global News. Sleep is the time when the brain “reviews and organizes what we experienced and learned during the day, so a day of study or learning can translate to better recall of the information.”
Qi, who is exploring this topic in an ongoing study, has found that keeping new information from slipping away is partially about planning your study sessions strategically to take advantage of the work the brain does at night.
She set out to explore if something as simple as changing when you study could help more of the knowledge stick.
The name of the project points to the central question: when is the best “Time2Learn”?
The project relies on some foundational knowledge of sleep and learning in the brain.
Ever wake up from catching some z’s and feel as if your mind downloaded a solution to a problem you had been pondering? All those hours you spent in bed, the brain was actually hard at work processing memories from the day before and filing away everything you learned.
People cycle through different stages throughout the night, and each supports learning and memory in specific ways, Qi said.
There’s the rapid eye movement (REM) stage, best known for dreams. That’s what’s happening when you see eye movements just under the eyelid of a sleeping person — or even in your dog. Research suggests REM sleep plays a particularly important role in cementing underlying language patterns, including aspects of speech and pronunciation, which are known as implicit knowledge. So in other words, even when you’re dreaming, you’re learning.
Then there’s deep sleep — a period of heavy-duty restoration, which is also when memories move from short-term into long-term storage. Specific information, such as new words and their meanings — known as explicit knowledge — gets consolidated during this stage.
Katherine Gordon from the Boys Town National Research Hospital, a pediatric research center in Village of Boys Town, Nebraska, pointed out that learning isn’t just about remembering certain things — it’s also about forgetting others.
“Across time, we need to figure out which information is important and which … is not important for a specific concept,” she said.
“That isn’t to say we can’t learn while awake,” Tony Cunningham, director of the Center for Sleep and Cognition, a research facility that studies how sleep shapes memory and emotional health, told Northeastern Global News. But sleep provides a particularly important window for consolidating what the brain took in during the day, he said.
“For a language learner, that’s the difference between memorizing a word and having it integrate with the vocabulary and grammar you already have,” he added.
That overnight work can have practical consequences, like asking for sugar when you wanted soup or accidentally calling someone’s mother a horse. Both are typical mix-ups that happen in Mandarin, where a difference in tone changes a word’s meaning. It’s exactly the type of rule that gets solidified during sleep.
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To find out if there’s a relationship between when you study and knowledge retention, Qi’s lab recruited participants who learned a sample language task. They completed three days of at-home speech training either in the morning or evening. They also tracked their sleep duration and quality with a watch-like device.
The challenge was learning to distinguish two unfamiliar speech sounds that can seem virtually identical to an untrained ear. Hindi, spoken in many parts of the Indian subcontinent, was chosen because it was one that the test subjects had never studied and because it contained the type of challenging sound contrast the researchers needed to measure how well people could learn a new speech distinction. Qi explained that the fact that people who hadn’t studied the language would find it hard to distinguish between certain speech sounds provided a clear before-and-after test. Could training teach their ears to pick up a difference they couldn’t hear before?
“We picked a very difficult problem to start with,” Qi said. “When I started this project, it sounded like the same sound to me,” she added.
The participants learned to associate each sound with a visual object, getting immediate feedback. A week later, they returned to the lab to see how well they could still tell the sounds apart.
At testing time a week later, the participants wore sensors placed on their scalp to let the researchers get a real-time readout showing if the brain’s response to the sounds was different. It served as a sign that the subjects learned to distinguish them. The sensors picked up the brain’s electrical activity through a method called electroencephalography (EEG). Researchers also tracked how well they retained the knowledge through on-site tests.
Qi also wants to see whether natural tendency toward learning in the evening or morning — a concept known as chronotype — plays a role.
The five-year study is still underway, and Qi stressed that the team doesn’t have conclusive results yet. However, one pattern has emerged so far: evening training appears to have an edge.
The researchers also noticed an advantage among night owls with learning these difficult speech contrasts.
Qi’s team is also asking another question. How do these patterns play out in people who have difficulties around language — ones that manifest in a condition known as developmental language disorder (DLD)?
Individuals with DLD might struggle with learning grammatical rules or repeating made-up words.
Child language specialist at the Boys Town National Research Hospital Karla McGregor pointed out that this difficulty applies to native and foreign languages alike.
Speech-language pathologist Tatyana Elleseff explained that children with DLD “may have more difficulty learning new vocabulary, holding onto unfamiliar word forms, detecting grammatical patterns, and processing verbal information quickly.” And learning a foreign language adds an extra challenge. They’re asked “to do all of those things again within a completely new linguistic system,” she said.
Understanding whether sleep and learning interact differently in people with DLD could eventually help researchers like Qi develop more targeted strategies for helping them overcome those language-learning challenges.
And as more people join the study, analysis of sleep-tracking data could reveal what role the quality and duration of sleep plays in retaining information learned during the day.
After all, as Leadley said, “even if someone spends hours studying, inadequate or disrupted sleep can interfere with the brain’s ability to retain that information.”
