Why sleep should be every student's priority

 Jakke Tamminen has plenty of students who do that very student 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.
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.
“Sleep is really a central part of learning,” he says. “Even though you’re not studying when you sleep, your brain is still studying. It’s almost like it’s working on your behalf. You can’t really get the full impact of the time you put into your studies unless you sleep.”
Inside the sleeper’s brain
We’re standing in Lab Room 1 of Tamminen’s sleep lab, a sparsely decorated room with a bed, a colourful rug, and framed paper butterflies. Above the bed is a small electroencephalography (EEG) machine and monitor to detect activity in each research participant’s brain, via electrodes placed on the head. These measure not only activity in different regions of the brain (frontal, temporal, and parietal), depending on their placement on the head, but also muscle tone (through an electrode on the chin) and eye movement (through an electrode next to each eye).
Down the hallway is the control room, where researchers can see in real time which parts of each volunteer’s brain are being activated, for how long, and to what extent. It’s easy to tell when a volunteer is in the rapid eye movement (REM) phase, based on the activity in the E1 and E2 (eye 1 and eye 2) graphs.
But more critical to Tamminen’s current research – and to sleep’s role in language development more generally – is a non-REM phase of deep sleep known as slow-wave sleep (SWS). SWS is important for forming and retaining memories, whether of vocabulary, grammar, or other knowledge. The interaction of different parts of the brain is key here. During SWS, the hippocampus, which is good at quick learning, is in constant communication with the neocortex, to consolidate it for long term recall. So the hippocampus might initially encode a new word learned earlier that day, but to truly consolidate that knowledge – spotting patterns and finding connections with other ideas that allow for creative problem-solving – the neocortical system needs to get involved.