BREATHING DISORDERS DURING SLEEP

National Institutes of Health
National Heart, Lung, and Blood Institute
"You Can Snore Your Life Away."

This sounds more like a joke than a warning. But, in fact, habitual loud snoring is the most common symptom of breathing disorders that occur during sleep. The person who snores not only sleeps restlessly, but also is at risk for serious disorders of the heart and lungs. Snoring can therefore be life threatening because it can lead to high blood pressure, irregular heartbeats, heart attacks, and sudden death.

Normal breathing must continue at all times whether awake or asleep. The act of breathing is an automatic, highly regulated mechanical function of the body. In healthy sleeping individuals, most muscular and neural activities will slow or even shut down but respiration goes on under a neuromuscular "auto pilot." However, if something goes wrong with the auto pilot during sleep, breathing may become erratic and inefficient.
Understanding Sleep

Sleep is a complex neurological state. Its primary function is rest and restoring the body's energy levels. Repeated interruption of sleep by breathing abnormalities such as cessation of breathing (apnea) or heavy snoring, leads to fragmented sleep and abnormal oxygen and carbon dioxide levels in the blood. Excessive daytime sleepiness and various disorders of the heart, lungs, and the nervous system result.
In the 1950's scientists realized that sleep is not just a quiet state of rest. In fact, two stages of sleep occur with distinct physiological patterns-rapid-eye-movement sleep (REM), and non rapid-eye-movement sleep (NREM) or deep sleep. In normal sleep, REM occurs about 90 minutes after a person falls asleep. The two sleep stages recur in cycles of about 90 minutes each, with three non-REM stages (light to deep slumber) at the beginning and REM towards the end. The amount of sleep needed by each person is usually constant although there is a wide variation among individuals.
How sleep occurs and how it restores the body are not well understood. Scientists originally believed that sleep occurs because the brain lapses into a passive resting state from lack of stimulation. Another theory proposed that sleep occurs when the body generates and accumulates sufficient amounts of a "sleep-inducing substance." However, research now suggests that sleep results when specific changes in brain function occur. By studying brain waves, scientists can define and measure various degrees, levels, and stages of sleep.

Sleep consists of a rhythmic combination of changes in physiological, biochemical, neurophysiologic and psychological processes. When the rhythm is disturbed or the individual processes are abnormal during sleep, a variety of sleep-related disorders may result.
Sleep-Related Disorders

Sleep-related complaints appeared regularly in medical literature in the beginning of the 19th century. However, from 1900 to the mid-1960s little was published in scientific journals about the "sleepy patient" except for an occasional report on the normal or abnormal aspects of sleep physiology. Recent developments of research techniques in neurobiology, molecular biology, molecular genetics, physiology, neuropsychiatry, internal medicine, pulmonary medicine, and cardiology have allowed scientists to study the details of sleep. As a result, there has been an explosion in interest in understanding sleep and "sleep disorders."
Some sleep-related disturbances are simply temporary inconveniences while others are potentially more serious. Sleep apnea is the major respiratory disorder of sleep. Other serious sleep-related disorders are narcolepsy and clinical insomnia. "Jet lag syndrome," caused by rapid shifts in the biological sleep-wake cycle, is also an example of a temporary sleep-related disorder. So are the sleep problems experienced by shift workers. Sleep apnea is the condition of interrupted breathing while asleep. "Apnea" is a Greek word meaning "want of breath." Clinically, sleep apnea, first described in 1965, means cessation of breathing during sleep.

Narcolepsy is a neurological disorder whose main symptoms in uncontrollable, excessive sleep, regardless of the time of day or whether the person has had enough sleep during the previous night. The other features of this disorder can include brief episodes of muscle weakness or paralysis caused by laughter and anger (cataplexy), paralysis for brief periods upon awakening from sleep (sleep paralysis), and dreamlike images at sleep onset (hypnagogic hallucination). Narcolepsy, which may affect several members of the same family, is a life-long condition. Medications help to reduce the symptoms but do not cure the disease.

Insomnia is the commonly experienced difficulty in falling asleep, remaining asleep throughout the night, and the inability to return to sleep once awakened. Its causes may be physical or psychological and it may occur regularly or only occasionally.

Even a partial list of all the disorders caused by or associated with disturbed sleep adds up to some 70 items. The costs to society due to loss of productivity, industrial accidents and medical bills are estimated to be over $60 billion. These staggering statistics led to the creation by the U.S. Congress in 1988 of a National Commission of Sleep Disorders Research. This group is charged with task of developing a blueprint for a national effort to reduce the medical and economic consequences of sleep disorders.

Likely Candidates for Sleep-Related Disorders

Some of the people most likely to have or to develop a sleep-related disorder include:

• adults who fall asleep at inappropriate times and places (e.g., during conversation, lecturing, driving) and who exhibit nighttime snoring
• elderly men and women
• postmenopausal women
• people who are overweight, or have some physical abnormality in the nose, throat, or other parts of the upper airway
• night-shift workers
• people who habitually drink too much alcohol
• blind individuals who tend to develop impaired perception of light and darkness and have disturbed circadian rhythms, the cycles of biologic activities that occur at the same time during each 24 hours
• People with depression and other psychotic disorders.

Sleep and Breathing Disorders

In 1944, the important observation was made that ventilation (exchange of air between the lung and environment) normally decreases during sleep. Even in "normal" people, breathing patterns during sleep may show a few irregularities. For example, a person might experience an average of seven breathing pauses of up to 10 seconds per night without any associated symptoms or problems. However if the breathing irregularities are accompanied by reduced oxygen supply to tissue (hypoxia) and repeated loss of sleep, these people are at risk of developing more serious problems.

Sleep Apnea

Sleep apnea is the most common sleep disorder in terms of mortality and morbidity, especially in middle-age men. Perhaps the best known sleep apnea "patient" is Charles Dickens' Fat Joe in The Posthumous Papers of the Pickwick Club, the overweight, red-faced boy in a permanent state of sleepiness, who snored and breathed heavily. The term "Pickwickian" syndrome is now used to describe patients with the most severe form of sleep apnea that is associated with reduced levels of breathing even during the day.

Sleep apnea occurs in all age groups and both sexes, but seems to predominate in males (it may be under diagnosed in females) and in African Americans. The Association of Professional Sleep Societies estimates that as many as 20 million Americans have this condition. The conditions associated with sleep apnea are a cascade: apnea, arousal, sleep deprivation, and excessive daytime sleepiness. Each is related to the frequency of the prior condition.

Like obesity with which it is often associated, the clustering of sleep apnea in some families suggests a genetic abnormality. Ingestion of alcohol and sleeping pills increases the frequency and duration of breathing pauses during sleep in people with or without sleep apnea.

Because of serious disturbances in their normal sleep patterns, patients with sleep apnea feel sleepy during the day and their concentration and daytime performance suffer. The common consequences of sleep apnea range from annoying to life-threatening. They include personality changes, sexual dysfunction and falling asleep at work, on the phone, or driving.

Symptoms of Sleep Apnea

Patients with sleep apnea have many repeated involuntary breathing pauses during sleep. The length of the breathing pause can vary within a patient, and among patients, and can last for 10 seconds to 60 seconds..

The breathing pauses are often accompanied by choking sensations which may wake up the patient, intermittent snoring, nighttime insomnia, early morning headaches, and excessive daytime sleepiness, although not all patients, for some reason, complain of daytime sleepiness. During the apnea events, a person may turn blue from low blood oxygen levels.

Other features of sleep apnea include slowing down of heart beat below 60 beats per minute (bradycardia), irregular heart beat (cardiac arrhythmias), high blood pressure (both systemic and pulmonary arterial), increase in red cells in the blood (polycythemia), and obesity. The absence of restful sleep may cause deterioration of performance, depression, irritability, sexual dysfunction, and defects in attention and concentration.

Types of Sleep Apnea

Scientists have distinguished three types of sleep apnea: obstructive, central, and mixed. However, since all three types can have the same symptoms and signs, a sleep evaluation is needed to tell the difference among them.

Obstructive Sleep Apnea (OSA) is the most common type. During OSA efforts to breath continue but air cannot flow out of the patient's nose or mouth. The patient snores heavily and has frequent arousals (abrupt changes from deep sleep to light sleep) without being aware of them.

OSA occurs when the throat muscles and tongue relax during breathing 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 conical fleshy tissue hanging from the center of the soft palate) relax and say, the airway becomes obstructed marking breathing labored and noisy. Airway narrowing may also occur due to overweigh, possibly because of the associated increases in the amount of tissue in the airway.

The reduction in oxygen and increase in carbon dioxide which occur during apnea cause arousals. With each arousal, a signal is sent to the upper airway muscles to open the airway; breathing is resumed with a loud snort or gasp. Although arousals serve as a rescue mechanism and are necessary for a patient with apnea, they interrupt sleep, and the patient ends up with less restorative and sleep than normal individuals.

Central Apnea occurs less frequently than obstructive apnea. There is no airflow in or out of the airways because efforts to breathe have stopped for short periods of time. In central apnea, the brain temporarily fails to send the signals to the diaphragm and the chest muscles that maintain the breathing cycle. It is present more often in the elderly than in younger people but often goes unrecognized.

In central apnea, there is periodic loss of rhythmic breathing movements. The airways remain open but air does not pass through the nose or mouth because activity of the diaphragm and the chest muscles stops. Patients with central apnea may not snore and they tend to be more aware of their frequent awakenings than those with obstructive apnea.

In Mixed Apnea, a period of central apnea is followed by a period of obstructive apnea before regular breathing resumes. People with mixed apnea frequently snore.

Snoring and Sleep Apnea

Snoring is a sign of abnormal breathing. It occurs when physical obstruction causes fluttering of the soft palate and the adjacent soft tissues between the mouth, external orifices of the nose (nares), the upper part of the windpipe (trachea), and the passage extending from the pharynx to the stomach (esophagus).
Snoring always occurs with obstructive sleep apnea. When diagnosing sleep disorders, obstructive sleep apnea is excluded if snoring is not a symptom. All snorers do not necessarily have sleep apnea; however, because they almost certainly have some physical obstruction in their airways, they may develop sleep apnea.

The prevalence of snoring is greater in the older population and apparently peaks in 60-year-old men and women, declining in older individuals. Men seem to snore more than women. Men also are more likely to develop sleep-disordered breathing. It is estimated that nearly half of all males over 40 snore habitually. Snoring is also more common in overweight people.

A visit to the doctor is not necessary when a person snores unless some of the other symptoms of sleep disordered breathing also occur. However, since snoring is an annoying or irritating symptom with some negative social aspects, many people have sought a "cure" for it. More than 300 devices have been patented in the U.S. which claim to control snoring. Many of these devices were developed even before medical scientists found out that heavy snoring is a potential marker of sleep apnea.

Sleep Apnea and the Heart

Sleep apnea and snoring seems to increase the likelihood of having a variety of cardiovascular diseases. These include high blood pressure, ischemic heart disease (a condition caused by reduced blood supply to the heart muscle), cardiac arrhythmias (abnormal heartbeat rhythm), and cerebral infarction (blood clot in the brain). It is not unusual for patients with sleep apnea to be mistakenly treated for primary heart disease because cardiac arrhythmias may be more prominent than the breathing disturbances.

Nearly 50 percent of sleep apnea patients have high blood pressure. Patients with the most severe sleep apnea seem to have the highest blood pressure levels and are also more likely to have trouble controlling their blood pressure than patients who do not have sleep apnea. No one knows whether a cause and effect relationship exists between high blood pressure and sleep apnea. If it does exist, the ways these conditions interact is unknown.
Snoring alone does not appear to be a risk factor for heart disease. Only when snoring occurs with sleep apnea or obesity does it seem to be associated with these conditions.

Get a Good Night’s Sleep

Like eating well and being physically active, getting a good night’s sleep is vital to your well-being. Here are some tips to help you:

1. Stick to a sleep schedule. Go to bed and wake up at the same time each day—even on the weekends.
2. Exercise is great but not too late in the day. Avoid exercising closer than 5 or 6 hours before bedtime.
3. Avoid caffeine and nicotine. The stimulating effects of caffeine in coffee, colas, teas, and chocolate can take as long as 8 hours to wear off fully. Nicotine is also a stimulant.
4. Avoid alcoholic drinks before bed. A "nightcap" might help you get to sleep, but alcohol keeps you in the lighter stages of sleep. You also tend to wake up in the middle of the night when the sedating effects have worn off.
5. Avoid large meals and beverages late at night. A large meal can cause indigestion that interferes with sleep. Drinking too many fluids at night can cause you to awaken frequently to urinate.
6. Avoid medicines that delay or disrupt your sleep, if possible. Some commonly prescribed heart, blood pressure, or asthma medications, as well as some over-the-counter and herbal remedies for coughs, colds, or allergies, can disrupt sleep patterns.
7. Don’t take naps after 3 p.m. Naps can boost your brain power, but late afternoon naps can make it harder to fall asleep at night. Also, keep naps to under an hour.
8. Relax before bed. Take time to unwind. A relaxing activity, such as reading or listening to music, should be part of your bedtime ritual.
9. Take a hot bath before bed. The drop in body temperature after the bath may help you feel sleepy, and the bath can help relax you.
10. Have a good sleeping environment. Get rid of anything that might distract you from sleep, such as noises, bright lights, an uncomfortable bed, or a TV or computer in the bedroom. Also, keeping the temperature in your bedroom on the cool side can help you sleep better.
11. Have the right sunlight exposure. Daylight is key to regulating daily sleep patterns. Try to get outside in natural sunlight for at least 30 minutes each day.
12. Don’t lie in bed awake. If you find yourself still awake after staying in bed for more than 20 minutes, get up and do some relaxing activity until you feel sleepy. The anxiety of not being able to sleep can make it harder to fall asleep.
13. See a doctor if you continue to have trouble sleeping. If you consistently find yourself feeling tired or not well rested during the day despite spending enough time in bed at night, you may have a sleep disorder. Your family doctor or a sleep specialist should be able to help you.
14. Almost half of all people with obstructive sleep apnea develop high blood pressure (hypertension), which raises the risk of heart failure and stroke.
    
15. People suffering from obstructive sleep apnea are up to 6 times more likely to be involved in a car crash as a result of drowsiness than those without sleep disorders.
    
16. The partner of an obstructive sleep apnea sufferer loses about an hour of sleep every night due to his or her partner’s snoring.
    
17. Sleep deprivation has been shown to alter hormones and metabolism involved in weight gain

Click Here For Information About Sleep Apnea

Click Here For Information About Snoring