BBC SCIENCE FOCUS MAGAZINE COLLECTION 89SLEEPABOVE: A participant sleeps
wearing a mask that delivers
smells in an experiment
to stimulate memories
during sleepnoses. 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
t hat if a n elect r ica l cu r rent is i njected i nto t he
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
having their brain artificially stimulated in
this way. The good news is t hat resea rcher s at
both Lübeck and Wisconsin have found that
simply playing tones at the right frequency
while asleep has a similar effect.
People who take Modafinil or Ritalin should
be drooling at natural ways to boost the brain.
But they aren’t the only ones who would benefit.
As we age, the amount of SWS we obtain in
a night declines. By 7 5 or so, many of us will
get none at all.
Importantly, it’s been found that the greater
the decline in SWS, the greater the cognitive
decline and some scientists believe the absence
of this critical sleep stage may be a factor in
the further degeneration of the brain.
If this is the case, then the artificial
stimulation could be a panacea for older
people, helping to restore their SWS and
stave off further cortical aging. Who knows,
we could soon all be getting a dose of sound
therapy while we sleep to keep our minds
sharp in old age.Find out how sleep
affects your brain in
How to Have a Better
Brain: Sleep
bbc.in/31f3sdUcognitive enhancer? The answer is that you
actually have a lot more control over these
things than you might think.
Sleep is locked to the circadian cycle, the
natural 24-hour rhythm of our bodies, and
you’re likely to get more REM in the morning
and more SWS in the afternoon or evening.
This means strategically planned naps can
help to ensure you get the kind of sleep you
want. Need to memorise a load of Spanish
vocabulary? Try an intense study session in
the late afternoon, followed by a SWS-filled
nap. Want to remember a highly emotional
wedding? A nap in the morning should help
out with a super dose of REM.
As well as controlling the phases of sleep,
we can also cause specific memories to be
replayed when we’ve nodded off. When sleep
researcher Björn Rasch was at the University
of Lübeck in Germany, he asked volunteers to
play a game. An array of matched card pairs
was spread out ‘face down’ on a computer
screen. They were then tasked with flipping
up one card and trying to remember the other
card that matched it. The volunteers played
this game several times until they had a good
memory of where every card was. While doing
this, the smell of roses was wafting in their
by DR PENELOPE LEWIS
Dr Lewis is a lecturer in neuroscience
at the University of Manchester.