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Allergic Bronchopulmonary Aspergillosis Apnea is cessation of airflow at the nostrils and mouth lasting at least 10 seconds. There are three types of apnea: obstructive, central and mixed. Obstructive apnea is secondary to upper airway collapse. Central apnea occurs when there is complete absence of a signal to breathe. Mixed apnea has features of both obstructive and central apnea. Apnea/hypopnea index (AHI) is the number of apneic and hypopneic episodes per hour of sleep determined by a sleep study that correlates with disease severity. Respiratory disturbance index (RDI) is synonymous with the apnea/hypopnea index in some sleep laboratories. The exact definition of the RDI is the total number of apneas, hypopneas, snore arousals and respiratory effort-related arousals per hour of sleep. Hypopnea is a reduction of airflow lasting 10 or more seconds measured on the sleep study by a 30 percent reduction in airflow associated with a drop in oxygen level by 4 percent. Hypopneas have the same clinical significance as an apnea. Arousal is a type of sleep disruption when there is an abrupt change from a deeper stage of sleep to a lighter stage of sleep or to wakefulness lasting a minimum of 3 seconds. Typically, you are not aware of arousals, but if they occur in sufficient numbers they will lead to unrestorative sleep. Awakening is a type of sleep disruption where there is a return to a state of wakefulness based on sleep study criteria. Respiratory effort-related arousal is a sequence of breaths lasting 10 or more seconds characterized by increasing respiratory effort or flattening of the airflow waveform leading to an arousal from sleep indicating partial upper airway obstruction. Snore arousal is a snoring event that leads to a sleep disruption, typically an arousal. Sleep efficiency is calculated during a sleep study or on the basis of sleep logs by dividing the time slept by time in bed. Arousal wake PLM index is the number of sleep-related periodic limb movements per hour of sleep associated with an arousal. Values greater than 5/hour are abnormal. Epoch is a 30-second interval of recording on a sleep study. Sleep latency is a time it takes a person to fall asleep. Less than 5 minutes or longer than 30 minutes is abnormal. Deep sleep is a common term for both slow wave and rapid eye movement sleep.
Alpha rhythm or activity is a brain wave rhythm with a range of 8-13 Hz (cycles/second) which occurs during wakefulness with eyes closed and during meditation. Beta rhythm or activity is a brain wave rhythm with a range of 13-35 Hz (cycles/second) associated with alert wakefulness or vigilance. It may be seen in drug-induced states. Delta rhythm or activity is a brain wave rhythm with a range of 0.5 to 3.5 Hz (cycles/second) associated with slow wave sleep. The individual waves must meet certain criteria including a peak-to-peak amplitude (height) of 75 microvolts and a duration of a half a second. For an epoch (thirty-second interval of sleep recording) to be classified as delta sleep or stage N3, more than 20% of that epoch must be delta rhythm. Theta rhythm or activity is a brain wave rhythm with a range of 3-7 Hz (cycles/second) which typically indicates Stage N1, a transitional stage of sleep. Sawtooth waves are a form of theta rhythm that occurs during REM sleep which has a notched waveform resembling the cutting edge of a saw. Sleep spindle is a spindle-shaped burst of 11.5-15 Hz (cycles/second) waves lasting 0.5-1.5 seconds, which is an identifying feature of Stage N2. K-complex is a brain wave which shows an initial sharp negative deflection followed by a high-voltage slow wave of at least 0.5 seconds often precipitated by noise which defines Stage N2 sleep. Hypersomnia is a term sometimes used to denote excessive sleepiness. It is also utilized as a diagnostic term in idiopathic hypersomnia. Sleep hygiene are common sense measures and practices that promote continuous and effective sleep. They include regular sleep/wake times, restricting bedroom activity to sleep and avoidance of naps, caffeine, alcohol and tobacco. Hypoxemia is a term used to denote reduced oxygen level in the blood. Oxygen saturation is the amount of oxygen bound to hemoglobin in the red blood cells. REM rebound is the lengthening and increasing frequency and depth of REM sleep which occurs when the depriving influence is removed from the setting of sleep deprivation. It is often seen in the first few nights after patients with obstructive sleep apnea syndrome are placed on CPAP. Sleep architecture is a term used to describe the structure and transitioning of sleep through all the stages.
Syndrome Z is a clustering of cardiovascular risk factors in some individuals including systemic hypertension, insulin resistance, elevated blood fats and central obesity which is known as Metabolic Syndrome, or “Syndrome X.” Recent publications have suggested that Syndrome X should incorporate OSA, and be re-labeled “Syndrome Z.” Obstructive Sleep Apnea Syndrome or obstructive sleep apnea hypopnea syndrome is a common sleep-related breathing disorder which is caused by repetitive partial or complete upper airway obstruction resulting in sleep fragmentation with consequences of daytime sleepiness, cognitive disturbances and cardiovascular and metabolic consequences. It is treated with surgery, oral sleep appliances or positive airway pressure devices. Prader-Willi Syndrome is a complex genetic disorder characterized by short stature, infantile hypotonia (loss of muscle tone), excessive eating urges, early onset childhood obesity, impaired sexual development, excessive daytime sleepiness, and impaired cognitive ability. The cause of excessive daytime sleepiness remains uncertain, but obstructive sleep apnea syndrome and hypothalamic dysfunction are both implicated. Central Sleep Apnea Syndrome is an uncommon form of sleep apnea where the brain either fails to send a signal for the person to breathe or sends a delayed signal or a reduced-intensity signal. It has different causes including the following: i. disease or injury involving the brainstem, such as a stroke, brain tumor, trauma or viral infection of the brain; ii. narcotic analgesics such as morphine or methadone; iii. congestive heart failure; iv. advanced, chronic respiratory illnesses; v. neurodegenerative disorders; or vi. it may be primary. Patients with central sleep apnea may not snore and more commonly complain of disrupted sleep. Treatments include medications to stimulate breathing, oxygen therapy or adaptive servoventilation. Multiple Sleep Latency Test (MSLT) is an objective test to determine the cause of unexplained excessive daytime sleepiness, to confirm the diagnosis of narcolepsy or idiopathic hypersomnia, or to help differentiate idiopathic hypersomnia from narcolepsy. Sometimes an MSLT is recommended to evaluate patients with OSAS who suffer with persistent sleepiness despite optimal treatment. The MSLT consists of five 20-minute nap opportunities performed at two-hour intervals during the day always after a nighttime sleep study. The MSLT measures sleep and REM latency, how long it takes a person to fall asleep and to achieve REM sleep during the naps. An average sleep latency of less than 8 minutes indicates an abnormal degree of daytime sleepiness. The presence of two or more naps with REM sleep indicates a diagnosis of narcolepsy. Maintenance of Wakefulness Test (MWT) is a validated objective measure of the ability to stay awake for a defined time used in association with the clinical history to assess the ability to maintain wakefulness. It is a daytime test to assess an individual’s ability to remain awake when his or her inability to remain awake constitutes a public or personal safety issue, especially in transportation workers including airline pilots, truck drivers and train conductors. The MWT consists of four trials where patients are challenged to stay awake sitting quietly for 40 minutes at two-hour intervals. Polysomnography is simply a sleep study or a diagnostic test where we observe you sleeping. Usually, it is performed at night but it may sometimes be done during the day. During the sleep study, we measure a number of different electrical signals from the body by attaching electrodes including brain waves, eye movements, and chin muscle tone to tell us if you are asleep and what stage of sleep. We also measure electrical activity from the heart (ECG), arm and leg. A flow sensor is placed in your nostrils to measure airflow. Belts are placed around the rib cage and abdomen for measurement of breathing movements. A clip is placed on a finger for measurement of blood oxygen levels. In patients with significant lung diseases, we may add capnography, a measurement of carbon dioxide level in the exhaled air. This helps detection of sleep-related breathing disorders where breathing is compromised. Other measurements may be done as required. Klein-Levin Syndrome is a rare and complex neurological disorder in adolescents characterized by cyclical (weeks, months, years) periods of excessive amounts of sleep and altered behavior. At the onset of an episode the patient becomes progressively drowsy and sleeps for most of the day and night (hypersomnolence), waking only to eat or go to the bathroom. When awake, the patient’s whole demeanor is changed, often appearing “spacey” or childlike. When awake, the patient experiences confusion, disorientation, complete lack of energy (lethargy), and lack of emotions (apathy). In some cases, food cravings (compulsive hyperphagia) and uninhibited hypersexuality may be exhibited. Individuals are not able to attend school, work or care for themselves. Most are bedridden, tired and uncommunicative even when awake. Night terrors (incubus, pavor nocturnes) is a sleep disorder characterized by sudden awakenings from sleep from a dream with associated screaming, sweating, confusion, rapid heart rate, or an inability to explain what happened but with a vague sense of having had a “bad dream” or nightmare. Night terrors occur in slow wave or delta sleep which usually occurs in the first half of the night. It is often associated with post traumatic stress disorder. Sleep walking or somnambulism is a sleep disorder characterized by persons getting up out of bed and walking around while they are still asleep. Others get up to perform purposeful activities such as daily routines while others perform actions that are crude, strange or misplaced. Occasionally, hostile or violent behavior has been reported. Sleepwalkers are difficult to awaken, when they do, they may be violent. They are never aware of their activities. It occurs in the first third of the night during slow wave or delta sleep. It is considered normal in children. They may walk outside. They may be a danger to themselves and to others. Somniloquy is sleep talking which is not considered a sleep disorder although you may say something that upsets the person listening. Rarely, it may indicate an underlying sleep disorder such as REM sleep behavior disorder, temporal lobe seizures, nightmares or night terrors. Confusional arousals or nocturnal sleep drunkenness are episodes of marked confusion during or after arousal from sleep, but without sleep walking or night terrors. During the episodes, the subject is not fully awake and may be very confused with slow mentation, be disoriented to time and place, and their perception may be impaired. Behavior is often inappropriate and thinking is confused and illogical. Rarely, aggressive behavior is observed and the person awakening the patient may get hurt. One patient’s wife used to awaken her husband with a broomstick. The patient has no recall of these episodes. Periodic Limb Movement Disorder (PLMD) is a neurological condition formerly called sleep myoclonus or nocturnal myoclonus with leg jerks or movements every 5 to 90 seconds on and off throughout the night sometimes leading to partial awakenings. The movements usually involve the lower extremities, consisting of extension of the big toe and flexion of the ankle, the knee and the hip. In some patients, the limb movements can occur in the upper extremities as well. Restless Legs Syndrome (RLS) is a neurological condition characterized primarily by vague or unpleasant sensations involving the lower extremities, sometimes the upper extremities which appears primarily during periods of inactivity, particularly during the transition from wake to sleep, but may occur during the day also. It may be associated with iron deficiency. Diagnostic criteria include the following:
Nocturnal Eating Syndrome (Sleep-Related Eating) NES is considered an eating and sleep disorder and occurs while the person is conscious. They experience recurrent episodes of eating during sleep, without being aware of what they are doing resulting in significant weight gain. It is more common in young women and those with depression and anxiety and those who suffer from insomnia. They consume half their calories after the evening meal and often skip breakfast. This condition can interfere with an individual’s nutrition, cause shame, and result in depression and weight gain. Nocturnal Sleep-Related Eating Disorder (NS-RED) is a sleep and eating disorder which occurs during sleepwalking. People with this disorder eat while they are asleep. They often walk into the kitchen and prepare food without any awareness or memory of having done so. A person with NS-RED can experience weight gain, increase their risk of developing type 2 diabetes, and cause shame and result in depression. Parasomnias are a group of sleep disorders characterized by arousals from deep sleep, either slow wave and REM sleep, manifested by movements, behaviors, and cognitive changes. Examples of parasomnias include bruxism, night terrors, nightmares, nocturnal enuresis, REM sleep behavior disorder, and sleep walking. Narcolepsy is a chronic neurological disorder caused by the brain’s inability to regulate normal sleep-wake cycles, especially REM or dream sleep. At various times while awake, people with narcolepsy experience characteristics of REM sleep including deep sleep, loss of muscle tone and dreaming. In addition to excessive daytime sleepiness (EDS), three other major symptoms frequently characterize narcolepsy: cataplexy, or the sudden loss of voluntary muscle tone; vivid hallucinations during sleep onset or upon awakening; and brief episodes of total paralysis at the beginning or end of sleep. Narcolepsy is typically diagnosed between the teenage through 30 years. It is thought to be due to decreased levels of orexin in the pons. Idiopathic Hypersomnia (HIS) is a chronic, neurological sleep disorder characterized by debilitating daytime sleepiness with associated great difficulty waking up and disorientation after awakening. IHS has two forms: idiopathic hypersomnia with long sleep time and idiopathic hypersomnia without long sleep time. Patients with a long sleep time sleep more than 10 hours each night, yet still experience sleepiness during the day. It is similar to narcolepsy but without the accessory symptoms of narcolepsy, such as cataplexy, sleep paralysis, or hypnagogic/hypnapompic hallucinations. Cataplexy is sudden loss of voluntary muscle tone without loss of consciousness while the person is awake. It is usually precipitated by intense emotions such as anger, anticipation, laughter or fear. It is a diagnostic sign of narcolepsy. Hypnapompic/hypnagogic hallucinations are vivid hallucinations during sleep onset or upon awakening, which are accessory symptoms of narcolepsy. Sleep paralysis is a brief episode of total paralysis lasting a few seconds or minutes at the beginning or end of sleep. It does not affect breathing or eye movements. It may occur as isolated sleep paralysis, narcolepsy or with profound sleep deprivation. Bruxism is described as a habit or a behavior, or a motor activity associated with tooth clenching or grinding. The prevalence of clenching is reported to be 20 percent, whereas sleep grinding is 6 percent of the adult general population. Clenching is mainly present during daytime and is suggested to be a behavioral response to stress, however, the role of stress in generating jaw muscle activity is controversial. Grinding is mainly reported to occur during sleep and may be secondary to pathophysiological changes related to sleep organization, autonomic and motor system excitability and probably to neurotransmitter imbalance such as dopamine. In adults, it may be associated with chronic pain, stress or poor alignment of upper and lower teeth. It is frequently seen in children with behavioral problems. It may result in dental wear and dysfunction of the temporomandibular joint. It may cause disturbed and unrestorative sleep. Relaxation training is a set of cognitive and behavioral techniques to diminish the physiological tension and stress associated with insomnia. Common forms are progressive muscle relaxation, diaphragmatic breathing and autogenic training. Autogenic training is one of several relaxation techniques where attention is focused on various regions of the body and to imagine that the region feels warm and/or heavy. The technique is designed to alter blood flow and to increase parasympathetic and decrease sympathetic nervous system activity. It helps alleviate concerns about being unable to sleep. Progressive Muscle Relaxation is a behavioral intervention for insomnia to teach individuals to recognize and reduce muscle tension. It is a series of exercises used to tense and relax each of the major skeletal muscle groups. Individuals are taught to focus on the physical sensations of tension and relaxation during these exercises. Melatonin is a hormone derived from serotonin and secreted by the pineal gland, usually in response to darkness. It is surmised that this hormone may be important for regulating the sleep-wake cycle. Circadian Rhythms are biological or behavioral functions that vary over the course of a 24-hour day and are synchronized to light/dark daytime cycles and/or sleep/wakefulness.
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