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Why sleep should be every student’s priority

It’s hard to overstate the benefits of a night’s rest for human memory, and

neuroscientists are just

beginning to understand why.

20 August 2018

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.

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.

View image of A woman sleeps on a yellow couch with a book

“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.

This information expressway between the hippocampus and the neocortex is

populated by sleep spindles –

spikes in brain activity that are no more than three seconds long.

“Sleep spindles are somehow associated with linking new information with

existing information,” Tamminen

says. And the data from his research participants suggests that people with

more sleep spindles have more

consolidation of the words they have learned. (Read more about how you can

learn in your sleep).

While Tamminen focuses on slow-wave sleep, there’s a theory that REM sleep

plays a role in language

development too, through the dreaming that happens during this part of the

sleep cycle. Research at the

sleep and dreams lab at Canada’s Ottawa University found that the brains of

undergraduates dreaming in

French were essentially able to make new connections with the language they

were learning.

Students intensively studying their second language had more REM sleep, giving

them more time to

integrate what they were learning while they slept

Dreams, after all, are more than simply a replay of what happens during the

day. Research has suggested

that the regions of the brain that manage logic (the frontal lobe) and emotion

(the amygdala) interact

differently during dreams, allowing for these imaginative new connections in

the language learner. And

students intensively studying the second language had more REM sleep. This gave

them more time to integrate

what they were learning while they slept – and better results during the day.

Nightly rhythms

There’s a genetic component to how many sleep spindles we have. There’s also a

genetic basis to our

internal clocks, which tell us when it’s time to go to sleep and wake up. And

adhering to these hard-wired

cycles is necessary to reaching our peak cognitive performance. (Read more

about why night owls shouldn’t

try to be morning people – and vice versa).

Few people know more about this subject than Michael W Young, who in 2017 was

awarded a joint Nobel Prize

in Physiology/Medicine for his work on clock genes with two co-researchers.

Young explains that for optimal

functioning – whether at school, work, or other areas of life – “what you want

to do is to try to recreate

a rhythmic environment”.

For a person whose lifestyle, environment, or inherited sleep disorder leads to

distorted sleep patterns,

“a cheap first-line response” could be using blackout curtains at night or

bright lights during the day to

mimic natural light/dark cycles as much as possible.

Power naps

The circadian rhythm’s role in adult learning is unquestionable, but its

importance may be particularly

pronounced in childhood.

Children have more slow-wave sleep than adults – which may be one factor

explaining how quickly kids learn,

in both language and other areas. The child sleep lab at Germany’s University

of Tuebingen investigates the

role of sleep in consolidating children’s memory. Monitoring what happens in

children’s brains during

sleep, and how much information they retain before and after sleep, shows that

sleep helps with accessing

implicit knowledge (procedural memory) and making it explicit (declarative

memory).

Adults can also call upon this kind of information learned during the day. But

as researcher Katharina

Zinke explains, “sleep is doing that in a more efficient way in children".

Children need to sleep during the day to remember everything that they have to

learn

“The effects are stronger in early childhood because the brain is developing,”

says Dominique Petit, the

coordinator of the Canadian Sleep and Circadian Network, who has also explored

the circadian rhythm in

children. In practical terms, this means that “children need to sleep during

the day to remember everything

that they have to learn".

"Daytime naps in young children have been shown to be really important for

vocabulary growth,

generalisation of the meaning of words and abstraction in language learning,"

she says. "Sleep continues to

be important for memory and learning throughout the lifetime, though.”

Not only does sleep help with accessing this information, it also changes the

way this information is

accessed. This makes brains more flexible at retrieving information (or able to

access it in more ways).

But it also makes them better at extracting the most significant parts of it.

“It’s actually an active process of strengthening and changing the memory

trace,” Zinke says. “Memory gets

transferred in a way that the most important information (the gist) is

remembered.”

Clearly, for children as well as adults, prolonged sleep isn’t a sign of

laziness in a language learner.

It’s critical for our brains’ connections and our bodies’ rhythms.

So, following your next intense Duolingo session, it’s a good idea to sleep on

it. You may be surprised the

next morning by how much you’ve absorbed.