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SLEEP
noses. After playing the game, everyone had
a normal night of sleep before a re-test the
next day. Some people were exposed to the
rose smell again before sleeping, some during
SWS and some during REM.
Interestingly, the people who smelled roses
again during SWS improved more than any of
the other participants. The same trick works
with sounds.
Exciting new developments have shown that
we might be able to take even more direct
control over our sleep phases in future. Prof
Lisa Marshall at the University of Lübeck found
that if an electrical current is injected into the
head at the same frequency that this firing
normally happens in SWS – just a little slower
than once a second – it produces the rhythmic
activity in the brain that even continues after
the current has been switched off. Although
technically fake, this ‘stimulated’ SWS
dramatically improves memory consolidation.
But not everyone will feel comfortable about
cognitive enhancer? The answer is that you ABOVE: A participant sleeps having their brain artificially stimulated in
wearing a mask that delivers
actually have a lot more control over these this way. The good news is that researchers at
smells in an experiment
things than you might think. to stimulate memories both Lübeck and Wisconsin have found that
during sleep
Sleep is locked to the circadian cycle, the simply playing tones at the right frequency
natural 24-hour rhythm of our bodies, and while asleep has a similar effect.
you’re likely to get more REM in the morning People who take Modafinil or Ritalin should
and more SWS in the afternoon or evening. be drooling at natural ways to boost the brain.
This means strategically planned naps can But they aren’t the only ones who would benefit.
help to ensure you get the kind of sleep you As we age, the amount of SWS we obtain in
want. Need to memorise a load of Spanish a night declines. By 75 or so, many of us will
vocabulary? Try an intense study session in get none at all.
the late afternoon, followed by a SWS-filled Importantly, it’s been found that the greater
nap. Want to remember a highly emotional the decline in SWS, the greater the cognitive
wedding? A nap in the morning should help decline and some scientists believe the absence
out with a super dose of REM. of this critical sleep stage may be a factor in
As well as controlling the phases of sleep, the further degeneration of the brain.
we can also cause specific memories to be If this is the case, then the artificial
replayed when we’ve nodded off. When sleep stimulation could be a panacea for older
researcher Björn Rasch was at the University people, helping to restore their SWS and
of Lübeck in Germany, he asked volunteers to stave off further cortical aging. Who knows,
play a game. An array of matched card pairs we could soon all be getting a dose of sound
was spread out ‘face down’ on a computer therapy while we sleep to keep our minds
screen. They were then tasked with flipping sharp in old age.
up one card and trying to remember the other
card that matched it. The volunteers played Find out how sleep
this game several times until they had a good affects your brain in by DR PENELOPE LEWIS
memory of where every card was. While doing How to Have a Better Dr Lewis is a lecturer in neuroscience
this, the smell of roses was wafting in their Brain: Sleep at the University of Manchester.
bbc.in/31f3sdU
BBC SCIENCE FOCUS MAGAZINE COLLECTION 89
