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Sleep is, as ancient maps once labeled uncharted
territories, where the dragons be. To go to sleep is to enter a world entirely
like our own and entirely unlike it, too. You can board a plane that’s really a
car that flies to Russia, except it’s the moon and your mom is there—until
she’s your dad. Dreams can be prosaic or repetitive (exactly how many times can
you show up at the same party in your underwear before you remember to put
something on?), but whatever they are, they remain mysterious. The sleeping
brain runs its absurdist-movie loop all night long, always taking care to
conceal what’s behind it. Right?
No longer. Neuroscientists have a growing arsenal
of tools—fMRIs, PET scans, high-density EEGs—to watch the nocturnal brain at
work and see how it ticks throughout the sleep cycle. To the surprise and
delight of researchers, that’s finally helping explain one of the mind’s most
ineffable qualities: creativity.
We’ve all slept on a problem and had it sort
itself out by morning. But that’s only a small part of what the brain on
nighttime autopilot can do. Paul McCartney famously said that he came up with
the melody for “Yesterday” in a dream; Elias Howe, the inventor of the sewing
machine, is said to have solved the problem of the machine’s needle when he
dreamed of an attack by warriors carrying spears with holes in the tips.
“Dreams are just thinking in a different biochemical state,” says Harvard
University psychologist Deirdre Barrett, author of The Committee of Sleep. “In the sleep state, the brain thinks much
more visually and intuitively.”
The hunt for the source of human creativity has
been going on for as long as people have been creating. It drives all of us to
wonder how celebrated inventors came up with ideas that became the next big
thing. And it drives us to wonder how we’ll find our own next brainstorm when
we need it. It’s no secret that sleep can be a well of good ideas—what we’re
learning now is how to dip into it.
You, uncensored
The act of sleeping, as researchers have long
known, is a lot more complicated than just conking out for the night. There are
two principal cycles of sleep: rapid eye movement (REM) and non–rapid eye
movement (NREM), and they alternate. NREM sleep starts as a light doze— sleep
at no greater than snorkeling depth—and steadily progresses to deeper levels at
which muscles relax, heart rate and respiration slow, and body temperature
drops.
REM sleep usually begins about 90 minutes after
the start of the first NREM cycle and is the true blue ocean of sleep. Heart
rate and respiration accelerate, and brain activity, as measured by
electroencephalograms (EEGs), increases too—a function of dreaming. For this
reason, muscles become paralyzed, lest you act out the scenes unspooling in
your head. Know those dreams in which you’re trying to run away from something
but can’t seem to move your legs? That’s not your imagination.
Most REM sleep comes in the last four hours of
sleep, says cognitive neuroscientist Jessica Payne of Notre Dame University.
“Dreams in the early, NREM phase can be kind of literal. It’s in the REM phase
that you get all these crazy binding errors.”
“Binding errors” is one of those lovely
scientific terms that mean pretty much what they sound like. Your waking brain
is orderly, your sleeping brain is fragmented, and as with all broken things,
the bits can get reassembled the wrong way. But “the wrong way” suggests that
there’s just one way, and the genius of sleep is that it allows you to explore
other, untried avenues.
In a frequently cited 2009 study, investigators
at UCLA and the University of California, San Diego, recruited a group of
volunteers and had them solve a type of word puzzle known as the
remote-association test (RAT). In a typical RAT question, subjects are given
three words and asked to determine a fourth word that links them all. The
answer for the words “broken,” “clear” and “eye,” for example, would be
“glass.” The volunteers had to take the test twice; between the two sessions,
they were told to take a 40-minute nap. Some just rested in that interval,
others dozed, and some tumbled into the depths of REM sleep. In Round 2 of the
tests, participants who got a slug of REM improved 40%, while the other
volunteers saw their scores go down. Sleep, it appeared, sharpened their
brains’ ability to find links among words.
A 2004 study from the University of Lübeck in
Germany approached the same idea in a more revealing way. Subjects were
required to complete math problems that relied on algorithms, but hidden deep
within the formulas was an elegant arithmetical shortcut. About 25% of the
subjects discovered it on their own. But that figure jumped to 59% when
volunteers were given a chance to get eight hours of sleep and then come back
for more.
“If you have an idea about a simpler solution and
it’s been working itself out in your head, you still tend to use the familiar
one,” says cognitive neuroscientist Howard Nusbaum of the University of
Chicago. When you sleep, the better answer has a chance to emerge.
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Portrait
of Juliette Courbet as a Sleeping Child, 1841 - Gustave Courbet/WikiArt
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The hard drive in your head
The key to the brain’s ability to make such good
use of downtime is something it shares with your computer: the capacity to run
multiple programs at once. The aha moment you experience when you’ve been
trying to remember the name of a song and three hours later it hits you is no
accident. “Conscious awareness is able to focus on only one thing at a time,”
says Barrett, “but problems go on getting processed under the radar.”
Sleeping doubles down on this. The prefrontal cortex
performs a traffic cop role, doing more than just keeping the brain focused on
a conscious task. It also screens out thoughts that it decides you oughtn’t
think of at all. The forbidden concepts aren’t just things that are socially
inappropriate—though those are on the list—but also those deemed rationally
inappropriate. In sleep, that brake on your imagination comes off, which
explains the German math study.
At the same time, the prefrontal censor is
dialing itself down, the brain’s visual centers, in the occipital lobe at the
back of the head, are dialing up. The hallucinogenic quality of dreams is a
result of the visual centers’ mixing images at will. That’s usually just chaff,
but not always. One night in 1816, Mary Shelley dreamed of a man assembled from
bits beyond the grave—and went on to write Frankenstein.
Just as important as which regions of the brain
are working is how they communicate. We think of the left hemisphere as the
rational, mathematical region and the right as the creative, more bohemian one,
and that’s a fair division. But a study conducted by neuroscientist Lisa Aziz-
Zadeh of the University of Southern California found that the brain is not
quite so bifurcated.
When architecture students undergoing functional
magnetic resonance imaging (fMRI) brain scans were asked to perform a
visual-spatial task—arranging geometric shapes in their heads to see if they
could be assembled into a square or a triangle— the right, artistic hemisphere
carried the load. When they were given a slightly more creative task—arranging
a circle, a C and an 8 in various ways to form a face—the right hemisphere
called on the assistance of the left. “The specific regions that are active
during the creative process largely depend on the kind of task the person is
engaged in,” says Aziz-Zadeh.
Another study at the University of Rome found
something similar. With the help of EEGs, investigators tracked communication
between hemispheres when subjects were awake, in NREM sleep and in REM. In the
waking and NREM states, information traveled mainly from left to right,
consistent with the idea that the left brain controls the right. During REM
sleep, however, there was no preferred direction. The right can thus come out
of the shadows.
Synapses—the cell-to-cell links that serve as the
bits of the brain’s operating system—play an important role too. Each brain
cell can link to more than just one other, and it would seem that the more
connections there are, the better, since that makes for a richer system. That’s
indeed true, but only to a point. Too many connections can lead to chaotic free
association rather than organized thought. So the brain must periodically clear
out the synaptic underbrush—analogous to “running a repair-and-cleaning program
on your computer to defrag the hard drive,” says psychologist William Killgore
of Harvard Medical School.
The hormone cortisol rises during REM, then helps
form new and imaginative ideas from the data that survives the defrag. Cortisol
is a stress hormone and tends to fracture memory. It has the same effect when
we’re asleep, and Payne believes this encourages the unbinding and rebinding of
images that can define dreams. “The brain dislikes fragmentation, so it weaves
narratives,” she says. “And that, in turn, gives rise to novel thinking.”
Dopamine is another ingredient in the brain’s
secret creative sauce. Harvard psychologist Shelley Carson points out that
dopamine levels rise in pleasure centers of the brain both when we’re dreaming
and when we’re being creative. This serves as a reward and reinforcement that
keeps the dreams—and ideas—flowing.
Controlling the process
As with all other matters scientific, the
question of causation comes up. Are we all equally imaginative in our sleep, or
do people who are already creative in their waking hours retain that edge at
night? Much as it would be nice to think that sleep is a great democratizer,
the fact is, creative types may indeed have an advantage around the clock. Psychologist
David Watson of the University of Notre Dame tracked 200 subjects over three
months and found that those who scored high on creativity scales when they were
awake tended to remember their dreams more.
“One reason is that they simply have more vivid
and interesting dreams,” he says. “That’s linked to having an active fantasy
life; the daytime behavior shades over into the night. This is a case of the
rich getting richer.”
That’s not to say the creative middle class can’t
aspire to join that metaphorical 1%. The best strategy for remembering dreams
is keeping a journal next to your bed, says Watson. Avoiding alcohol and
caffeine is also wise, since they scramble the NREM and REM cycles.
Barrett’s
studies suggest that engaging in some type of pre-bedtime priming—contemplating
a problem you’d like to solve—increases the likelihood that sleep will bring
some answers. Up to a third of the subjects in one of her sample groups
reported that priming had helped them find a solution that had eluded them during
the day.
None of this guarantees that a good night’s sleep
is the panacea for what ails you creatively. But neither does it change the
fact that the odds are in your favor. You have problems every day, and you go
to bed every night. But even if you don’t think of yourself as creative, your
sleeping brain will sometimes prove otherwise.
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