A Glossary of Sleep
AASM – American Academy of Sleep Medicine
Age and Sleep
American Academy of Sleep Medicine
Auto PAP (Auto adjusting Positive Airway Pressure)
BiPAP (Bi-level Positive Airway Pressure)
Central Sleep Apnea
CPAP (Continuous Positive Airway Pressure)
DME (Abbreviation for Durable Medical Equipment)
Full Face Mask
Multiple Sleep Latency Test
Obstructive Sleep Apnea
OSA (Obstructive Sleep Apnea)
PSG (Abbreviation for Polysomnography)
Sleep Medicine Specialist
Split Night Sleep Study
Stage 3 and 4 Sleep
Stage I Sleep
Stage II Sleep
Titration Study (CPAP Titration)
Sleep is vitally important. We know that all mammals sleep. We think that all reptiles and birds sleep. There is behavioral evidence that even insects sleep. We know that adequate sleep is important for normal daytime functioning. Lack of sleep results in poor memory, mood disturbance, accidents while driving, accidents at work, poor concentration, irritability, inability to learn and numerous other problems. Animal studies suggest that lack of sleep may even be fatal. We do not know how sleep loss causes all these problems. Sleep Medicine and the study of sleep are relatively new fields and there is still much to be learned. There has been an explosion of interest in this field in the last 15 years and we hope to answer the basic riddle of why we sleep in the next 15 years.
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Sleep Stages - Sleep in humans consists of 5 stages. These stages are characterized based primarily on EEG (electrical activity of the brain). Stage 1 sleep is "light" sleep and is a transition stage between wakefulness and sleep. A patient in Stage I sleep, if woken up, will report that they were awake and others perceive they were asleep. Stage 2 sleep is a deeper sleep which occupies the majority of the night in adults. Stages 3 and 4 sleep are characterized by the presence of delta waves (slow waves) in the EEG with Stage 4 having more delta activity then Stage 3. REM sleep is the stage during which we have of a very vivid dreams. During REM sleep, the EEG appears almost awake but there are other characteristics that define this stage. Rapid eye movements can be recorded and there is loss of muscle tone. In fact, we are totally paralyzed during REM sleep.
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Amount of Sleep - The amount of sleep required for proper daytime functioning varies from person to person for any given age. Infants may sleep 16 hours or more per day. There is a gradual decline in the amount of sleep needed during childhood. Then there is an increase during the growth spurt of adolescence. The average high-school student needs about 9 hours of sleep. The average fifth grade child needs somewhat less. The requirement for sleep is less in adults. The average adult needs 7.5 - 8 hours of sleep per night. The elderly probably need the same amount but have a hard time getting proper sleep because of many factors including illness, medication, the need to get up during the night and a tendency to wake up early in the morning.
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Circadian Rhythm - There is a natural rhythm affecting our tendency to fall asleep during a 24 hour day. There is a natural tendency to be drowsy in the early afternoon which is why we nap after lunch. There are times of day that is almost impossible to fall asleep regardless of how sleep deprived we are, typically late mornings (10 AM) and in the evening 7 9 PM. Then of course we are highly likely to fall asleep in the late evenings 10 PM to midnight. The maximum drive to sleep occurs in the early morning hours 2 AM 4 AM. There are a number of physiologic changes that occur as we cycle through our daily circadian rhythm. Body temperature drops during sleep. There are changes in growth, adrenocortical and other hormones through the day and night.
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The circadian rhythm is important because it leads to sleep problems. We can only change our bedtime and wake time by an hour or two per day. This results in jet lag and shift work problems for example. Teenagers in particular are troubled as a result of their natural circadian rhythms. They find it very difficult to fall asleep at 9 or 10 PM and need 9 hours of sleep. As a result, they find it very difficult to get up at 7 AM. This problem has led to the move to change high school start times.
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What is a Sleep Center
All of our Sleep Disorders Center facilities are (or soon will be) accredited by the American Academy of Sleep Medicine (AASM). The AASM is the national organization that has been responsible for the explosion of interest and research in sleep medicine. Virtually all practitioners in the field are members. The AASM certifies that each facility performs sleep studies according to standards published by the AASM and that the patients are managed appropriately. There are 2 levels of certification. A Sleep Center is accredited to diagnose and treat all sleep disorders. A Sleep Apnea Lab is accredited only to evaluate sleep apnea. A Sleep Center must have a medical director that is board certified as a Specialist in Sleep Medicine. Accreditation of a sleep facility is an arduous process requiring close attention to all aspects of operation, similar to the accreditation process that hospitals undergo periodically. All our SDC sites are accredited by the AASM as full service Sleep Centers within 1 year of opening.
An important concept has evolved over the last 10 years regarding the role that a Sleep Center should play. It is no longer enough to simply perform a diagnostic test. The AASM expects the Sleep Center to also ensure that patients have adequate follow up and treatment. Sleep apnea patients in particular need follow up. In the past, patients were simply started on CPAP without adequate follow up and ended up untreated as a result. This unfortunate result can often be avoided with education and training efforts. The key to treatment is to make sure that patients are periodically seen by a doctor with expertise in the evaluation and treatment of sleep disorders.
There are many people who are critical to operation of a sleep lab, none more than the Sleep Technicians. The tech's are the ones who actually run sleep studies. They will greet the patient when they arrive at the Sleep Center, explain the process, put on all the wires and monitors, watch all the signals on the computer through the night, adjust the CPAP as necessary, score' the sleep study and in general help the patient through a test unlike anything they've experienced. This is a difficult physically demanding job because there are so many elements involved, not the least of which is the need to be awake all night constantly evaluating complex physiologic data as it is acquired.
A board exam is available for sleep technicians. Generally at least two years of experience and ongoing training are necessary to pass this exam. A board certified sleep tech can be proud to put the title RPSGT (Registered Polysomnography Technician) after their name. We are proud to say that all technicians who have been with us 3 or more years have board certification!
The other key person in a sleep center is the Technical Director. This is a senior technician who supervises the night technicians and is responsible for ongoing quality control efforts as dictated by the AASM. The technical director is available to help patients who are having problems adjusting to CPAP or have other questions.
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There are several types of sleep study. The primary and most commonly done study is a polysomnogram. This is usually done during a full night's sleep although it may be done during the day in a shift worker who normally sleeps during the day. During a sleep study, a number of physiologic variables are recorded. This usually includes 4 or more channels of EEG, a recording of air flow from the nose and mouth, an oxygen monitor on the finger or the ear lobe, EKG, belts that record movement of the chest and abdomen, muscle activity around the chin and the lower leg. These monitoring electrodes and transducers are placed by a polysomnography technician (sleep tech). T his is a painless process that takes 30 - 45 minutes in a cooperative adult and may take much longer in a child. Once the wires are in place, the patient is requested to turn out the lights and try to fall asleep. Once asleep, all the data is recorded by a computer for later analysis.
A titration study is a full night polysomnogram that is done in patients who have sleep apnea. During a titration study, the patient is started on CPAP and the pressure is adjusted until normal breathing resumes. The patient may also be tried on BiPAP. Another form of titration study is a split night study. Some patients with severe sleep apnea can be proven to have significant problems with breathing after only 2 or 3 hours of sleep. In that case, the sleep study may be stopped and then restarted with CPAP. In other words the study is split' between a typical polysomnogram and a titration study.
A Multiple Sleep Latency Test (MSLT) is also known as a nap study. This is done to document daytime sleepiness, typically in a patient thought to have Narcolepsy. This is usually started in the morning after an overnight sleep study. The patient has a number of recording electrodes but it differs from an overnight study in that air flow, rib belts, abdominal belts, EKG and oxygen are not recorded. The patient is asked to take a 20 minute nap every 2 hours through the day starting at 8:00 a.m. usually. There will be 4 or 5 naps depending on the results. The primary measures are the average length of time to fall asleep in the naps (less than 10 minutes is considered abnormal) and the presence of REM. Excessive REM sleep is seen with Narcolepsy (REM sleep in 2 or more of the naps). REM sleep normally is present in at most one nap during an MSLT.
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Sleep apnea is a serious disorder that interrupts a person's breathing during sleep, sometimes for several seconds and hundreds of times during the night. Sleep Apnea is characterized by pauses in breathing many times during sleep; these breathing pauses can last for as long as a minute. With each apnea event, the brain briefly rouses the sleeper in order for breathing to resume. As a result, sleep is fragmented and of poor quality. Common symptoms of sleep apnea include excessive daytime sleepiness and loud snoring, though everyone who snores does not have sleep apnea. Sleep apnea can trigger other, potentially fatal health problems including high blood pressure, cardiovascular disease, memory problems, impotence, and morning headaches. Sleep apnea can strike anyone at any age, including children and even athletes. Those at the highest risk are overweight and over 40.
There are 2 forms of sleep apnea obstructive and central. Obstructive Sleep Apnea (OSA) is far more common, affecting up to 5% of the adult population. It is due to collapse of the airway. It is often related to obesity but may be seen in thin individuals as well. OSA results in repeated episodes of partially decreased airflow (hypopnea) or total loss of airflow (apnea) despite efforts to breathe. Central Sleep Apnea is uncommon and is not due to airway collapse. It is due to loss of effort to breathe. It is seen in congestive heart failure, neuromuscular disorders, severe strokes and sometimes no obvious cause can be found.
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This is the classic pure sleep disorder. This is disease causing severe daytime drowsiness regardless of how much sleep is obtained. Irresistible daytime sleep episodes may cause severe problems working, going to school, driving, etc. It is a disorder of REM sleep regulation that results in normal REM phenomena (sleepiness, muscle paralysis/weakness, dreams) appearing when patients are fully awake. There are 4 symptoms:
1. Daytime Somnolence this is present in all patients and can be severe
2. Sleep Paralysis this is a frightening symptom. The patient will wake from sleep totally unable to move. This always resolves, usually in less than a minute. This symptom may be seen in normal individuals. Some studies have shown that up to 50% of the normal population may have this at least once in their lifetime.
Hypnogogic Hallucinations These are dreams that break into the waking state. Like sleep paralysis, this occurs when awakening from sleep. The patient will report being fully awake but still having vivid dreams. Technically this would be termed a hallucination. It is not a sign of mental illness.
Cataplexy this is an unusual symptom consisting of muscle weakness affecting parts or all of the body. This can lead to falls with injuries but this is unusual. These attacks often have a recognizable trigger, often laughing or being angry. If present, it is diagnostic of Narcolepsy.
The last 3 symptoms above (ancillary symptoms) are not seen in all patients with narcolepsy. The only symptom seen in all patients is daytime sleepiness (which can be seen for numerous other reasons).
The diagnosis is made by doing an extensive history to rule out other sleep disorders, an overnight sleep study to rule out sleep apnea and an MSLT to measure the degree of sleepiness and to look for sleep onset REM sleep during naps. REM sleep appearing in 2 or more of the naps is considered diagnostic for narcolepsy.
Treatment of drowsiness involves wake promoting medications such as Provigil or stimulants such as Ritalin, Adderall or Dexedrine or a new class of medication, Xyrem. The other symptoms, particularly cataplexy, can be treated with a variety of antidepressants or with Xyrem. Xyrem is the only medication known that can treat both the somnolence and the ancillary symptoms.
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Insomnia is very common. It is defined as a problem either initiating or maintaining sleep. Virtually everyone has experienced a night where it is difficult to get to sleep (initial insomnia) or to stay asleep (maintenance insomnia). It is estimated that up to 30% of the population in the US may have insomnia frequently enough that treatment should be considered. There are numerous reasons for insomnia, many of which are easy to figure out. This includes caffeine usage too late in the day, stress, snoring bed partners, medication effects, pain problems, etc. Some of the causes are not as obvious, such as Restless Legs Syndrome, mood disorders, nocturnal reflux and others. There has been a major revival of interest in insomnia in the research community recently. In the last year (2005) alone, 3 new medications have been released for treatment of insomnia Ambien CR, Lunesta and Rozerem.
The diagnosis and treatment of insomnia is a complex topic and an important one. A Sleep Medicine Specialist can be very helpful. A consultation with one of our doctors often leads to better sleep.
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CPAP, BIPAP, AND AUTOPAP
CPAP Continuous Positive Air is forced into the airway at a set Pressure. The airflow is constant and holds the airway open at a set pressure when breathing in and out. This pressure can vary from 4 25 depending on the amount of air required to hold open a person's airway and stop the obstructions that are occurring.
BIPAP Bi-level Pressure that allows for a higher pressure when breathing in and a lower pressure when breathing out. This pressure can also vary from person to person.
AUTOPAP The device will recognize if an obstruction occurs and will increase the pressure until the obstruction is overcome. This device is great for someone who needs a wide variation in pressure through the night (ex: needs 20 cm when supine but only 8 cm when on the side) or for someone that a definitive setting cannot be obtained in the lab.
Getting Acquainted to CPAP
There are many different ways for people to become acquainted with their unit. Some people find it very easy to use from the beginning. Others find a period of time is needed to become comfortable with the machine. Finding the correct mask for the user can often be a challenge. One mask does not work for everyone. Sometimes it takes sampling different types of masks to find the one. Keeping in contact with the Durable Medical Equipment (DME) company that provides the machine and supplies is important. If a patient is having a problem, contacting the equipment company for assistance is essential.
If a patient is claustrophobic, the best solution is to use a mask that is less obtrusive. There are many newer masks on the market that do not have to be strapped to the patient's head tightly. Secondly, start off using the unit slowly to get familiar with the machine. This will help you to acclimate to the mask and the treatment.
The upper airway has two responsibilities to the lungs. First, it works as a filter to pick up the dust particles that are breathed. By pushing the air into your airway at a higher pressure your airway is not able to do this efficiently. The machine will come with filters that will replicate this action. Replacement of these filters is very important. Insurance companies are aware of this and will pay for the replacement filters on a monthly basis. Secondly, your airway adds humidity to the air you breathe. The air pressure from the machine is bypassing the ability to add this humidity, therefore a humidifier is often ordered by the physician when the machine is prescribed.
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Masks used with CPAP / BiPAP
Nasal Mask This is a placed over the nose only. The major advantage is that a seal is required over a relatively small area. The major disadvantage is that mouth breathers cannot use this type of mask. If the air from the CPAP is delivered through a nasal mask, the air will leak out of the mouth and will not effectively hold the airway open.
Full Face Mask - this mask type fits over the nose and the mouth. It is the only option for a mouth breather. Because it must seal over a larger area, it tends to leak more than a nasal mask.
Nasal Pillows - There are several varieties of masks that use nasal pillows'. These masks have small prongs that are very soft and fit into both nostrils to deliver air directly in to the nose. These mask types are less bulky and easier to maintain a seal.
Common Problems with CPAP / BiPAP
1. Mask Leaks Usually caused by a poor fitting of the mask. Call the Durable Medical Equipment / Home Health Company and inquire about being fitted with a better fitting mask. The mask may simply need to be adjusted differently. Over time, the mask will begin to age and mask leakage is an indication that a new mask is needed.
2. Nasal Dryness CPAP/ BiPAP units blow air into your airway and dryness can occur. Heated humidification added to the unit can fix the problem. By increasing the heat on the humidifier, the humidity will be increased.
3. Nose Bleeds Usually results from excessive dryness and should not persist more than two days. If persistent, contact your sleep physician's office.
4. Mask Removal at Night This can be a normal response when becoming acquainted to the unit. This should stop after a short time. The pressure of the machine may need to be adjusted if it does not. Please contact your physician for help with this.
5. Mouth Opening This problem can be solved by using a full face mask or using a chin strap. Contact your home healthcare provider.
6. Snoring The pressure may be too high or too low on the machine. Mouth breathers may need a full face mask. Weight gain may also increase snoring. Schedule an appointment with your sleep physician.
7. Skin Irritation A reaction to a new mask or problems with pressure on your face from a mask needs to be communicated to the equipment company first an d if they cannot help, contact your sleep physician's office.
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Durable Medical Equipment Company
This is a source for home medical supplies, home medical equipment and health care supplies. CPAP, BiPAP, and AutoPAP machines as well as masks, humidifiers, headgear, and other supplies are available. The physician will order the necessary equipment and the company will supply the equipment and educate the patient on the use and cleaning of the equipment.
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A humidifier is a container of water that puts moisture in the air leaving the CPAP machine. Basically the air coming from the machine blows into the humidifier, bubbles through the water and then travels through a hose to the patient. Several of the problems listed above respond to humidification of the air. Humidifiers may be a separate device or may be built-in with the CPAP machine. Most of the newer models of CPAP/BiPAP/Auto PAP have built in humidifiers. There are 2 types of humidifier cool and heated. Cool humidifiers have distilled water at room temperature. Heated humidifiers have a heating coil that warms the distilled water most of the heaters have adjustable temperature settings. Heated humidifiers cost a little more but are usually worth it because heated water warms the air which can carry more moisture than cool air (ever notice how a hot shower clears your nasal passages?). Many sleep specialists order a humidifier with every CPAP/BiPAP/Auto PAP machine.
Cleaning Your CPAP/ BiPAP Machine
It is important to keep the CPAP/ BiPAP unit and the filters, hoses, humidifier, and mask clean. Daily cleaning with warm soapy water followed by rinse is recommended. Hanging the hoses and mask up will allow for complete drying. Upper respiratory infection can occur if the supplies and unit are not kept clean.
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