Sleep Apnea Filter Facts
What is Sleep Apnea?
apnea can be an acute, potentially life-threatening condition that is far more common
than generally understood. First diagnosed and defined in 1965, sleep apnea is a
breathing disorder characterized by brief interruptions of breathing during sleep.
a given night, the number of involuntary breathing pauses or "apneic events" may
be as high as 20 to 30 or more per hour. These breathing pauses are almost always
accompanied by snoring between apnea episodes, although not everyone who snores has
this condition. Sleep apnea can also be characterized by choking sensations. The
frequent interruptions of deep, restorative sleep often lead to early morning headaches
and excessive daytime sleepiness
are two types of sleep apnea: central and obstructive. Central sleep apnea, which
is less common, occurs when the brain fails to send the appropriate signals to the
breathing muscles to initiate respirations. Obstructive sleep apnea is far more common
and occurs when air cannot flow into or out of the person's nose or mouth although
efforts to breathe continue.
Who Gets Sleep Apnea?
apnea occurs in all age groups and both sexes but is more common in men (it may be
underdiagnosed in women) and possibly young African Americans.
has been estimated that as many as 18 million Americans have sleep apnea. Four percent
of middle-aged men and 2 percent of middle-aged women have sleep apnea along with
excessive daytime sleepiness.
most likely to have or develop sleep apnea include those who snore loudly and also
are overweight, or have high blood pressure, or have some physical abnormality in
the nose, throat, or other parts of the upper airway. Sleep apnea seems to run in
some families, suggesting a possible genetic basis.
How Is Normal Breathing Restored During Sleep?
the apneic event, the person is unable to breathe in oxygen and to exhale carbon
dioxide, resulting in low levels of oxygen and increased levels of carbon dioxide
in the blood. The reduction in oxygen and increase in carbon dioxide alert the brain
to resume breathing and cause an arousal. With each arousal, a signal is sent from
the brain to the upper airway muscles to open the airway; breathing is resumed, often
with a loud snort or gasp. Frequent arousals, although necessary for breathing to
restart, prevent the patient from getting enough restorative, deep sleep.
What Causes Sleep Apnea?
mechanical and structural problems in the airway cause the interruptions in breathing
during sleep. In some people, apnea occurs when the throat muscles and tongue
relax during sleep and partially block the opening of the airway. When the muscles
of the soft palate at the base of the tongue and the uvula (the small fleshy
tissue hanging from the center of the back of the throat) relax and sag, the
airway becomes blocked, making breathing labored and noisy and even stopping
it altogether. Sleep apnea also can occur in obese people when an excess amount
of tissue in the airway causes it to be narrowed. With a narrowed airway, the
person continues his or her efforts to breathe, but air cannot easily flow into
or out of the nose or mouth. Unknown to the person, this results in heavy snoring,
periods of no breathing, and frequent arousals (causing abrupt changes from deep
sleep to light sleep). Ingestion of alcohol and sleeping pills increases the
frequency and duration of breathing pauses in people with sleep apnea.
How Is Sleep Apnea Diagnosed?
addition to the primary care physician, pulmonologists, neurologists, or other
physicians with specialty training in sleep disorders may be involved in making
a definitive diagnosis and initiating treatment. Diagnosis of sleep apnea is
not simple because there can be many different reasons for disturbed sleep. Several
tests are available for evaluating a person for sleep apnea.
is a test that records a variety of body functions during sleep, such as the
electrical activity of the brain, eye movement, muscle activity, heart rate,
respiratory effort, air flow, and blood oxygen levels. These tests are used both
to diagnose sleep apnea and to determine its severity.
Multiple Sleep Latency Test (MSLT) measures the speed of falling asleep. In this
test, patients are given several opportunities to fall asleep during the course
of a day when they would normally be awake. For each opportunity, time to fall
asleep is measured. People without sleep problems usually take an aver-age of
10 to 20 minutes to fall asleep. Individuals who fall asleep in less than 5 minutes
are likely to require some treatment for sleep disorders. The MSLT may be useful
to measure the degree of excessive day-time sleepiness and to rule out other
types of sleep disorders.
tests usually are performed in a sleep center, but new technology may allow some
sleep studies to be conducted in the patient's home.
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