foodconsumer.org: Secret to a Good Night's Sleep is in the "Waves"

Secret to a Good Night's Sleep is in the "Waves"
================================================================================
Rachel Stockton on 08/11/2010 20:34:00
 
Ever wonder why some babies wake up with every tiny little noise, and some sleep
through normal household noises and even barking dogs or playing siblings?  Or
why you startle awake at every sound whether it is whispering in the next room
or a fire engine driving down your street?  Do you sleep beside someone who can
sleep through a hurricane it seems, and requires a lot of physical and vocal
stimulus to wake them?
Researchers from Boston's Harvard Medical School, Massachusetts General Hospital
and Brigham and Women's Hospital may have found the 'secret' to an uninterrupted
night's sleep.  Their research has been published in today's issue of Current
Biology.
Quality sleep is essential to good health and well-being.  The body requires 7-8
hours of uninterrupted sleep to ward off lethargy, inattentiveness and general
grumpiness.  Fractured sleep is disturbingly prevalent in our society leading to
chronic sleep deprivation causing irritability, depression and increased risk of
obesity.   One of the contributing factors to sleep fagility is the ability to
block out noise.
“The goal of this research agenda is to make the sleeping environment really a
utopia,” says Jeffrey Ellenbogen, a neurologist and sleep specialist at
Harvard Medical School and Massachusetts General Hospital in Boston. But in
order to achieve that goal, the researchers needed to know what happens during a
night of good sleep.
The study focused on how sensitivity to noise during sleep is associated with a
type of brain activity called sleep “spindles," also known as brain waves.  
Described as bursts of fast brain rhythms that punctuate the otherwise slow-wave
patterns characteristic of sleep, these spindle rhythms originate out of the
thalamus, which is located at the top of the brainstem and is known to affect
motor control, and receive and relay auditory, somatosensory and visual sensory
signals.
Spindles are known to be part of the brain’s response to shutting out external
stimuli, therefore researchers were especially interested in how many spindles
each person had throughout the night.
Originating in the thalamus, a part of the brain which monitors sensory
information, sleep spindles prevent night noises from reaching your brain and
waking you.
On the first night of testing this theory, they measured the spindle rhythms of
about a dozen volunteers in a quiet sleep environment using an
electroencephalogram (EEG). On two subsequent nights, the same volunteers
returned to the center and were exposed to loud noises during sleep such as road
noise and ringing telephones.
Volunteers barely noticed disturbances to their sleep, and responded to
questions about the quality of sleep from the night before as having very few
interruptions. Some recalled being awakened a couple of times during the night
by loud sounds, however, researchers had played 60 sounds and woken the people
up 30 to 40 times.
“It’s a very clever study,” says Mathias Basner, a sleep researcher at the
University of Pennsylvania in Philadelphia. Researchers have previously
associated spindles with blocking out sound, but this study suggests that
spindles are an inborn characteristic of each person.
Even on quiet nights, some people have far more spindles than others.  People
with fewer spindles are more sensitive to noise and will awaken more easily and
more often.
Basner notes it is too soon to tell whether the number of spindles a person’s
brain produces each night is a trait that is set in stone, or if the brain can
train itself to deal with noisy environments.
Dr. Ellenbogen said, "If a spindle occurs at the same time as a sound, then the
sound is likely blocked from perception, keeping the person asleep. More
spindles make it more likely that noises will collide with this sleep-protecting
rhythm.”
Understanding sleep spindle production may assist development of drugs or other
treatments to increase the number of spindles a person produces lessening
sensitivity to noise during sleep, but Ellenbogen stresses researchers would
need to be sure that any spindles produced by such therapies actually do the
same thing as naturally occuring spindles.
“Synthetic sleep is not something that is attractive to me,” he says.
“What I want is to enhance natural sleep.”
Failure to get a good night's sleep could be a symptom of an underlying medical
condition such as sleep apnea, depression, anxiety disorder,  congestive heart
failure, medication side-effect or coronary artery disease (especially in
females).  If you have difficulty staying asleep and are not sure of the cause,
contact your health care professional.
Laura Lamp King