Sleep apnea is a serious, potentially life-threatening
condition that is far more common than generally understood.
First described in 1965, sleep apnea is a breathing disorder
characterized by brief interruptions of breathing during
sleep. It owes its name to a Greek word, apnea, meaning
"want of breath." There 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.
In 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.
Early recognition and treatment of sleep apnea is important
because it may be associated with irregular heartbeat, high
blood pressure, heart attack, and stroke.
WHO GETS SLEEP APNEA?
Sleep 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. It 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. People 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.
WHAT CAUSES SLEEP APNEA?
Certain 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 NORMAL BREATHING RESTORED DURING SLEEP?
During 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
WHAT ARE THE EFFECTS OF SLEEP APNEA?
Because of the serious disturbances in their normal sleep
patterns, people with sleep apnea often feel very sleepy
during the day and their concentration and daytime
performance suffer. The consequences of sleep apnea range
from annoying to life-threatening. They include depression,
irritability, sexual dysfunction, learning and memory
difficulties, and falling asleep while at work, on the
phone, or driving. It has been estimated that up to 50
percent of sleep apnea patients have high blood pressure.
Although it is not known with certainty if there is a cause
and effect relationship, it appears that sleep apnea
contributes to high blood pressure. Risk for heart attack
and stroke may also increase in those with sleep apnea. In
addition, sleep apnea is sometimes implicated in sudden
infant death syndrome.
WHEN SHOULD SLEEP APNEA BE SUSPECTED?
For many sleep apnea patients, their spouses are the first
ones to suspect that something is wrong, usually from their
heavy snoring and apparent struggle to breathe. Coworkers
or friends of the sleep apnea victim may notice that the
individual falls asleep during the day at inappropriate
times (such as while driving a car, working, or talking).
The patient often does not know he or she has a problem and
may not believe it when told. It is important that the
person see a doctor for evaluation of the sleep problem.
HOW IS SLEEP APNEA DIAGNOSED?
In 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.
Polysomnography 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.
The 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 average 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
daytime sleepiness and to rule out other types of sleep
Diagnostic tests usually are performed in a sleep center,
but new technology may allow some sleep studies to be
conducted in the patient's home.
HOW IS SLEEP APNEA TREATED?
The specific therapy for sleep apnea is tailored to the
individual patient based on medical history, physical
examination, and the results of polysomnography.
Medications are generally not effective in the treatment of
sleep apnea. Oxygen administration may safely benefit
certain patients but does not eliminate sleep apnea or
prevent daytime sleepiness. Thus, the role of oxygen in the
treatment of sleep apnea is controversial, and it is
difficult to predict which patients will respond well. It
is important that the effectiveness of the selected
treatment be verified; this is usually accomplished by
Behavioral changes are an important part of the treatment
program, and in mild cases behavioral therapy may be all
that is needed. The individual should avoid the use of
alcohol, tobacco, and sleeping pills, which make the airway
more likely to collapse during sleep and prolong the apneic
periods. Overweight persons can benefit from losing weight.
Even a 10 percent weight loss can reduce the number of
apneic events for most patients. In some patients with mild
sleep apnea, breathing pauses occur only when they sleep on
their backs. In such cases, using pillows and other devices
that help them sleep in a side position is often helpful.
Physical or Mechanical Therapy
Nasal continuous positive airway pressure (CPAP) is the most
common effective treatment for sleep apnea. In this
procedure, the patient wears a mask over the nose during
sleep, and pressure from an air blower forces air through
the nasal passages. The air pressure is adjusted so that it
is just enough to prevent the throat from collapsing during
sleep. The pressure is constant and continuous. Nasal CPAP
prevents airway closure while in use, but apnea episodes
return when CPAP is stopped or used improperly.
Variations of the CPAP device attempt to minimize side
effects that sometimes occur, such as nasal irritation and
drying, facial skin irritation, abdominal bloating, mask
leaks, sore eyes, and headaches. Some versions of CPAP vary
the pressure to coincide with the person's breathing
pattern, and others start with low pressure, slowly
increasing it to allow the person to fall asleep before the
full prescribed pressure is applied.
Dental appliances that reposition the lower jaw and the
tongue have been helpful to some patients with mild sleep
apnea or who snore but do not have apnea. Possible side
effects include damage to teeth, soft tissues, and the jaw
joint. A dentist or orthodontist is often the one to fit
the patient with such a device.
Some patients with sleep apnea may need surgery. Although
several surgical procedures are used to increase the size of
the airway, none of them is completely successful or without
risks. More than one procedure may need to be tried before
the patient realizes any benefits.
Some of the more common procedures include removal of
adenoids and tonsils (especially in children), nasal polyps
or other growths, or other tissue in the airway and
correction of structural deformities. Younger patients seem
to benefit from these surgical procedures more than older
Uvulopalatopharyngoplasty (UPPP) is a procedure used to
remove excess tissue at the back of the throat (tonsils,
uvula, and part of the soft palate). The success of this
technique may range from 30 to 50 percent. The long-term
side effects and benefits are not known, and it is difficult
to predict which patients will do well with this procedure.
Laser-assisted uvulopalatoplasty (LAUP) is done to eliminate
snoring but has not been shown to be effective in treating
sleep apnea. This procedure involves using a laser device
to eliminate tissue in the back of the throat. Like UPPP,
LAUP may decrease or eliminate snoring but not sleep apnea
itself. Elimination of snoring, the primary symptom of
sleep apnea, without influencing the condition may carry the
risk of delaying the diagnosis and possible treatment of
sleep apnea in patients who elect LAUP. To identify
possible underlying sleep apnea, sleep studies are usually
required before LAUP is performed.
Tracheostomy is used in persons with severe, life-
threatening sleep apnea. In this procedure, a small hole is
made in the windpipe and a tube is inserted into the
opening. This tube stays closed during waking hours, and
the person breathes and speaks normally. It is opened for
sleep so that air flows directly into the lungs, bypassing
any upper airway obstruction. Although this procedure is
highly effective, it is an extreme measure that is poorly
tolerated by patients and rarely used.
Other procedures. Patients in whom sleep apnea is due to
deformities of the lower jaw may benefit from surgical
reconstruction. Finally, surgical procedures to treat
obesity are sometimes recommended for sleep apnea patients
who are morbidly obese.
NATIONAL CENTER ON SLEEP DISORDERS RESEARCH (NCSDR)
The mission of the NCSDR is to support research, training,
and education about sleep disorders. The center is located
within the National Heart, Lung, and Blood Institute (NHLBI)
of the National Institutes of Health. The NHLBI supports a
variety of research and training programs focusing on
cardiopulmonary disorders in sleep, designed to fill
critical gaps in the understanding of the causes, diagnosis,
treatment, and prevention of sleep-disordered breathing.
National Center on Sleep Disorders Research
Two Rockledge Centre Suite 7024
6701 Rockledge Drive MSC 7920
Bethesda, MD 20892-7920
(301) 480-3451 (fax)