Jakke Tamminen has plenty of students who do that very studenty thing of staying up all night right before an exam, in the hope of stuffing in as much knowledge as they can. But “that’s the worst thing you can do”, the psychology lecturer at the UK’s Royal Holloway University warns them.

He should know. Tamminen is an expert on how sleep affects memory, specifically the recall needed for language. Sleep learning – another idea beloved of students, in the hope that, say, playing a language-learning recording during sleep would imprint itself into the brain subliminally and they’d wake up speaking Latin – is a myth.

But sleep itself is essential for embedding knowledge in the brain, and the research of Tamminen and others shows us why that is.

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In Tamminen’s ongoing research project, participants learn new vocabulary, then stay awake all night. Tamminen compares their memory of those words after a few nights, and then after a week.

Even after several nights of recovery sleep, there is a substantial difference in how quickly they recall those words compared to the control group of participants who didn’t face sleep deprivation.