Sleep Apnea - Breathing Disorders In Sleep: Sleep Disorders

Content provided by the Faculty of the Harvard Medical School

Sleep apnea

Sleep apnea is a life-threatening condition that affects approximately 18 million adults in the United States, and is most common among overweight men. In sleep apnea, the airway becomes blocked or breathing muscles stop moving. Breathing stops or becomes shallower hundreds of times each night. People with sleep apnea are often less aware of their fatigue and sleepiness than are people with other types of sleep disturbances. Sleep experts say that doctors should be more vigilant in diagnosing apnea because it contributes not only to daytime sleepiness, but also to traffic accidents, cognitive difficulties, and heart problems.

Until recently, sleep apnea was considered uncommon, and it often remained undiagnosed. Physicians rarely checked for it except in the stereotypical patient — an overweight, middle-aged man who snored. But in 1993, researchers at the University of Wisconsin School of Medicine learned that apnea is more common in both men and women than previously thought. They looked for sleep apnea in 602 state employees, ages 30–60, as part of a larger sleep study, and were surprised to find that 9% of women and 24% of men had at least five episodes of reduced breathing, or hypopnea, per hour. About 4% of men and 2% of women were estimated to have the full syndrome of sleep apnea, which includes abnormal breathing events and daytime sleepiness.

Obstructive sleep apnea

Obstructive sleep apnea occurs when the upper airway is blocked by excess tissue such as a large uvula, tongue, tonsils, fatty deposits in the airway walls, nasal congestion, or a floppy rim at the back of the palate. People with sleep apnea tend to have smaller airway openings than those who don't. A narrow airway makes obstruction all the more likely when airway muscles relax at the onset of sleep.

A potentially life-threatening lack of oxygen and buildup of carbon dioxide, as well as increasing efforts to breathe, cause the sleeper to awaken and gasp loudly for air until blood oxygen levels return to normal. At worst, a person with obstructive sleep apnea cannot breathe and sleep at the same time.

Some people with sleep apnea repeat this cycle hundreds of times a night without being fully aware of what is happening. They don't realize how little sleep they're actually getting and may routinely feel lethargic. Others wake up after bouts of apnea and have difficulty getting back to sleep; they reason that insomnia — not a breathing problem — makes them sleepy during the day. The condition can become even more perilous if a person with apnea is treated with sleeping pills that further relax airway muscles or suppress arousal or breathing.

Symptoms and signs of obstructive sleep apnea are as follows:

• Snoring. Although many snorers have no medical problems, the hallmark of apnea is frequent snoring that is loud enough to disturb a bed partner. The snorer may choke, gasp, or appear to hold his or her breath during sleep.

• Thick neck. Men with a neck circumference of 17 inches or greater have a 50% chance of having sleep apnea. Neck size greater than 16 inches increases the risk in women.

• Hypertension. More than half of patients with sleep apnea have high blood pressure. Research has shown that sleep apnea is a cause of hypertension.

• Grogginess, fatigue, and sleepiness. People with obstructive sleep apnea are excessively sleepy during the day and have two to six times as many traffic accidents as individuals without this condition.

Sleep apnea can wreak havoc on the cardiovascular system because the heart must work harder every time blood oxygen levels dip. People with the disorder have a higher risk for stroke, heart attack, and heart failure. Arrhythmias (irregular heartbeats) may accompany apnea spells.

Upper airway resistance syndrome. While investigating obstructive sleep apnea, scientists have discovered subtler types that may elude standard tests. Obstructive sleep apnea occurs on a spectrum from a wide open airway (no problem) to a completely blocked airway. In one recently recognized type, sometimes called upper airway resistance syndrome, the airway is only slightly narrowed but people must work extra hard to inhale, although they have no significant drop in blood oxygen levels. This extra work wakes them up many times each night, and they may complain of insomnia or daytime sleepiness. The same treatments that help individuals with a fully closed airway are also effective for this type.

Central sleep apnea

This condition occurs when respiratory centers in the brain fail to send the necessary messages to initiate breathing. Although the airway isn't blocked, the diaphragm and chest muscles stop moving. Shortly, falling blood oxygen and rising carbon dioxide levels set off an internal alarm, prompting resumption of breathing and often waking the person. Central sleep apnea becomes more common as people age, and it is more frequent and severe in those with chronic lung disease, congestive heart failure, or neurological damage. People with central sleep apnea are usually aware of waking up during the night and often complain of daytime sleepiness.

Ondine's curse is a rare form of central sleep apnea caused by damage to the brain stem. The disorder takes its name from a German legend about a water nymph named Ondine who married a mortal. When her husband proved all too human and jilted her, the king of the water nymphs punished him by taking away his autonomic functions, including breathing. He died when he forgot to breathe. People with Ondine's curse have slow and shallow respiration. During the day, they can remind themselves to breathe deeply, but at night they don't get enough oxygen. Ondine's curse leads to serious medical complications and eventually death.

Sleep apnea in babies

Sleep apnea in babies has been linked with sudden infant death syndrome, although the precise relationship is unclear and still under investigation. Older children with sleep apnea may be overweight but most commonly have very large tonsils and adenoids; removing these tissues solves the problem. Unrecognized sleep apnea in children can be devastating; at school a child's sleepiness may be misinterpreted as lack of motivation or intellectual dullness, and the child may be diagnosed as having attention deficit disorder. Paradoxically, some children respond to sleep deprivation with hyperactivity, which can be very disruptive in school. In severe cases, a child may be deprived of oxygen to such an extent that permanent brain damage occurs.

Treatments for apnea

Lifestyle changes, medication, air pressure devices, oral appliances, and surgery are used to treat obstructive sleep apnea. Physicians usually advise people with this condition to lose weight and avoid alcohol and sedatives. Sleeping in a different position may help if you experience apnea only when lying on your back. If the appropriate lifestyle changes don't reduce apnea, continuous positive airway pressure (CPAP) or oral appliances may be effective. Selective serotonin reuptake inhibitors (SSRIs) have a mild positive effect on airway muscle tone and are helpful for some people. In some cases, surgery may be necessary. It's best to get a second opinion from a specialist with expertise in sleep disorders before agreeing to surgery.

Therapy for central sleep apnea usually involves treating the underlying medical condition that has disrupted breathing. Sometimes CPAP, oxygen, or medications are helpful (see Table 2).

Continuous positive airway pressure (CPAP). Usually, this is the first treatment recommended for people with sleep apnea. If you have obstructive sleep apnea, CPAP can keep your airway open during breaths, preventing airway collapse and making sleep more restful. It may also help some people with central sleep apnea sleep better. The CPAP devices use a compressor to deliver pressurized air through a mask that fits snugly over your nose or nose and mouth. The machine can be placed on a night stand by the bed. CPAP has become more comfortable in the past few years; newer models are lighter and quieter, and many offer options such as warmed humidified air (which alleviates nasal congestion, skin dryness, and dry mouth) and an internal regulator that eases pressure when you're breathing well on your own.

The CPAP device keeps the airway open during sleep by providing a pressurized flow of air. Newer models for home use are more comfortable than earlier versions.

People usually try CPAP for the first time in a sleep laboratory. A technician adjusts the pressure while the patient sleeps. Most people find it difficult at first to breathe out against a constant stream of air and to learn to sleep with their mouth closed. However, there is generally a great improvement in the amount of time spent in restorative deep sleep. Many people report a superb night's rest immediately, and tests show their alertness is improved the next day. In many cases, CPAP also reduces or eliminates hypertension. For some people, CPAP may be a lifelong treatment.

Bi-level positive airway pressure (bi-level PAP). For people who have difficulty exhaling against the pressure of CPAP, a refinement called bi-level PAP (often referred to by the trademarked name BiPAP) may be more tolerable. It delivers air under high pressure as the sleeper inhales and switches to lower pressure during exhalation.

Oral appliances. Oral appliances that reposition the lower jaw and tongue, permitting the airway to remain open, can reduce or eliminate sleep apnea. Such devices are available from dentists trained in treating sleep apnea.

Corrective jaw surgery. Surgery to move the upper or lower jaw forward may enlarge the upper airway for some people with obstructive sleep apnea.

Somnoplasty. Along with treating snoring, somnoplasty (see "Somnoplasty") also is sometimes used to treat sleep apnea when other treatments have not helped. It's not yet known what percentage of patients benefit from somnoplasty.

Tracheostomy. Tracheostomy, the first treatment for sleep apnea, is rarely used today. In tracheostomy, the surgeon makes a small hole through the lower neck into the airway below its point of collapse and inserts a tube. During the day, the tube is plugged; at night, it's opened to allow air to enter, bypassing the obstructed area. Tracheostomy is 100% effective, but it is reserved for life-threatening cases or when all other treatments have failed.

Uvulopalatopharyngoplasty (UPPP). In UPPP, a surgeon removes loose or excess tissue from the uvula, the tonsils, and a rim of loose tissue at the edge of the soft palate. Although the operation is often described as a "tightening of loose tissue" or a "revision" of the upper airway, it involves removing anatomical structures. Recovery is similar to that following a tonsillectomy: You usually have a severe sore throat for a couple of weeks. The hospital stay usually lasts two days, and you'll be monitored overnight to assess the effectiveness of the procedure. UPPP helps about half of those who undergo it. The rest may need to have further upper airway surgery or use CPAP.

Last updated:	January 23, 2007