Shows Why Getting Up
Too Early May Be Counterproductive
The wannabe super-achiever who spends too much time getting ready
for the big day at the expense of getting enough sleep is probably
doing precisely the wrong thing.
Researchers at Harvard University have found new evidence that
the brain continually reorganizes itself while the host is snoozing
away. A nap in the afternoon probably boosts performance, but
it's no substitute for getting a full night's sleep because those
last couple of hours of slumber are when the brain tells itself
to pay attention to what's going on.
It is during that critical phase that the brain sends "funny
looking wave forms" that tell some brain cells to beef up their
connections with other neurons, says Mathew Walker of the Harvard
Medical School's department of psychiatry. Walker, lead author
of a report published in the July 3 issue of the journal Neuron,
says those wave forms apparently work as "powerful triggers" that
tell our brain something we've been working on is important, thus
improving our performance the next day by committing a learned
skilled to the memory banks.
Honing Skills in Your
That electrical activity, called "sleep spindles," can be measured,
and the research shows that spindles abound toward the end of
the sleep period.
"It just so happens that when you track the amount of these
spindles that the human brain has during the regular eight-hour
period of sleep, they seem to ramp up and have very high intensities
in the last two hours of the night," Walker says. "It's specifically
those two hours that we have found to be most important."
So the person who hops out of bed after six hours sleep and
goes forth to use newly learned skills to slay a dragon has managed
to shut down that critical phase of mental activity just as it
was getting started. His new skills likely won't be nearly as
potent as they might have been.
Significantly, this apparently applies to a wide range of human
endeavors, from playing a musical instrument to hitting a golf
ball to pounding on a keyboard. All of those depend on something
scientists call the "procedural memory system," and it involves
learning all types of skills.
For part of the research, Walker and his colleagues took 62
right-handed persons and asked them to type a sequence of numbers
(4-1-3-2-4) with their left hand as quickly and as accurately
as possible. On average the performance of the participants improved
about 60 percent just by repeating the task over and over.
Nap Minimum: One Hour
The participants were then divided into subgroups, and one group
was tested again after staying awake for 12 hours. They showed
no improvement. But when tested after a full night's sleep, they
improved by 19 percent.
Another group improved by 20.5 percent after a night's sleep,
but gained only 2 percent after staying awake for 12 hours. After
a full night's sleep, their performance jumped again by nearly
Other research showed that the improvement in performance was
directly related to the completion of a full eight hours of sleep.
The last two hours, Walker says, turned out to be the most important.
In a related project, other Harvard researchers found that a
midday nap does much to recharge the system by allowing the brain
to consolidate the memories of habits, actions and skills learned
during the day, according to Robert Stickgold of the department
of psychiatry. A nap, he says, gives the brain a chance to avoid
"burnout" and reorganize itself, perhaps bringing new circuits
in to relieve some that had grown weary.
That short of a snooze, however, is no substitute for a full
night's sleep, the researchers say.
And to be much help at all, the nap needs to be about an hour
long. Try explaining that one to the boss.
This is still a relatively new field, and much remains to be
learned about what the brain is up to while we think it's just
sleeping, but what is emerging loud and clear is the fact that
sleep is far more critical than most of us might think.
Sleep = Work
We may think our brain is "dormant" while we're asleep, Walker
says, but it's actually firing off commands and doing all sorts
of things to restore our biological systems to good working order.
"You spend about a third of your life asleep, and I don't think
mother nature is stupid enough to keep you asleep for a third
of your life to do just one thing and one thing only," like rest
your weary bones, he says.
"You don't spend two thirds of your life awake just doing one
thing. You do many things while you are awake."
Researchers are finding, he says, that parts of the brain are
as active when we are asleep as when we are awake."
And the new research suggests that if we cut back even a little
on our sleep, we're reducing the brain's ability to commit what
we have learned to memory, whether it's typing, designing a rocket
engine, or learning a new dance step.
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