Why Sleep Is Precious
You really are harming your brain when you don't get enough zzz's ...
As told to Gabrielle Redford by Dr. P. Murali Doraiswamy
"Night owls, take note. That sleep deficit you've been accumulating has real and dangerous implications for your brain, and not just because it makes you sleepy during the day. Sleeping less than seven or eight hours a night has been linked to cognitive decline, memory loss and possibly even Alzheimer's, new research shows.
Dr. Doraiswamy, a brain researcher at Duke University in Durham, North Carolina, explains what your brain does during sleep.
Clears out toxins
Most people think that when you sleep, your brain goes to sleep, too.
But it turns out that parts of your brain are several times more active
at night than during the daytime. One of them is a newly discovered
drainage system called the glymphatic system, which is kind of like your
city's sewage and recycling system; its job is to clear out and recycle
all your brain's toxins. One protein very actively recycled during
sleep is involved in developing amyloid plaque, the hallmark of
Alzheimer's. No one is saying that Alzheimer's is all caused by sleep
deprivation, but it may be a factor.
Repairs daily wear and tear
New research indicates chronic sleep deprivation can lead to
irreversible brain damage. A University of Pennsylvania animal study
found that extended wakefulness can injure neurons essential for
alertness and cognition — and that the damage might be permanent. Short
sleep may also be linked to shrinking brain volume, though it's not
clear whether the lack of sleep causes the brain to shrink or whether a
smaller brain makes it harder to sleep. Other studies have led
scientists to conclude that chemicals secreted during the deeper stages
of sleep are crucial for repairing the body — including the brain.
Makes order from chaos
As you go about your daily activities, your brain is exposed to
thousands of stimuli — auditory, visual, neurosensory. And it can't
possibly process all that information as it comes in. A lot of the
tagging and archiving of memories occurs at night while you're sleeping.
It's a bit like what goes on in a library. All the books dropped off in
the book repository during the day are dusted off and cataloged at
night. People who think they've adapted well to sleeping just four or
five hours a night are often wrong; memory tests show they are not
functioning optimally.
Creates memories
One of the chemicals involved in creating memories — acetylcholine — is also involved in sleep and dreaming. What happens
in people who start to develop Alzheimer's is that the brain cells that
produce acetylcholine are destroyed, so people stop dreaming as much.
Interestingly, a side effect of the most commonly used drug to treat
Alzheimer's — Aricept — is its ability to induce vivid dreams."
