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While many American's suffer from
not enough sleep, those with sleep apnea may be more
than tired; they may be more at risk for stroke and
death.
 This
new study showed that sleep apnea itself was a risk
factor for stroke, even without other risk
factors present. The sleep disorder
permanently reduces the brain's ability to regulate
blood flow to itself.
These findings show that not only
should the risk factors for sleep apnea be addressed
but the problem itself to prevent other injury to
the body.
The full report from the
The American Physiological Society is below.
Study Helps Explain Connection
Between Sleep Apnea, Stroke And Death
Researcher offers tips to watch
for in identifying risks
 BETHESDA,
Md. (Jan. 6, 2009) − Obstructive sleep
apnea decreases blood flow to the brain, elevates
blood pressure within the brain and eventually harms
the brain's ability to modulate these changes and
prevent damage to itself, according to a new study
published by
The American Physiological Society.
The findings may help explain why people with sleep
apnea are more likely to suffer strokes and to die
in their sleep.
Sleep apnea is the most commonly diagnosed
condition amongst sleep-related breathing disorders
and can lead to debilitating and sometimes fatal
consequences for the 18 million Americans who have
been diagnosed with the disorder. This study
identifies a mechanism behind stroke in these
patients.
The study, (impaired cerebral autoregulation in
obstructive sleep apnea) was carried out by Fred
Urbano, Francoise Roux, Joseph Schindler and Vahid
Mohsenin, all of the Yale University School of
Medicine in New Haven, Connecticut. It appears in
the current issue of the Journal of Applied
Physiology.
During sleep apnea episodes, the upper airway
becomes blocked, hindering or stopping breathing and
causing blood oxygen levels to drop and blood
pressure to rise. The person eventually awakens and
begins breathing, restoring normal blood oxygen and
blood flow to the brain.
Ordinarily, the brain regulates its blood flow to
meet its own metabolic needs, even in the face of
changes in blood pressure -- a process known as
cerebral autoregulation. This study found that the
repeated surges and drops in blood pressure and
blood flow during numerous apnea episodes each night
reduces the brain's ability to regulate these
functions.
Condition a health risk
Up to 4% of the population suffers from
obstructive sleep apnea. In a previous study, Dr.
Mohsenin and his colleagues showed that people with
sleep apnea are three times more likely to suffer a
stroke or die, compared to people in a similar state
of health but without sleep apnea.
"After we found that sleep apnea is a risk factor
for stroke and death, independent of other risk
factors, we hypothesized that there must be
something wrong with the regulation of blood flow to
the brain," Dr. Mohsenin said. Participants included
people with severe sleep apnea who experienced more
than 30 apneas an hour during sleep time. The
participants were about 47 years old, were free of
cardiac disease and had not experienced any strokes.
The study also included a control group which did
not have sleep apnea but was similar in most other
ways.
The researchers monitored the participants' blood
pressure while standing and squatting. Standing from
a squatting position lowers blood pressure as can be
experienced during normal daily activity. They also
monitored the participants as they slept. The study
found that the sleep apnea group:
had lower cerebral blood flow velocity
had significantly lower blood oxygen levels
during sleep
took longer to recover from a drop in blood
pressure
took longer to normalize blood flow to the
brain
 Identification
is key
Overall, the findings indicate that repeated
surges and drops in blood pressure and low oxygen
levels eventually impair the body's ability to
regulate blood flow to the brain. Sleep apnea may
occur over a long period of time before the person
becomes aware of it and seeks medical treatment.
Here are the symptoms Dr. Mohsenin says to watch out
for:
After eight hours of sleep, you don't feel
rested. During the day, you feel more and more
tired, and by afternoon, you want to nap.
You experience loud, habitual snoring that
disturbs others.
Your bed partner observes pauses in your
breathing.
The treatment of obstructive sleep apnea with an
airway pressurization mask has been shown to
normalize cerebral autoregulation, although there
are not yet any studies to show that it reduces the
rate of stroke. Those who are being treated for
sleep apnea should remain compliant with treatments,
according to Dr. Mohsenin, including use of
air pressurization mask or CPAP
nasal inserts
dental appliances
weight reduction for the obese
In some cases, surgery may be advised.
Funding: Yale University, Department of
Medicine and Yale Center for Sleep Medicine
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