Sleep Apnea Definitions

Sleep Medicine Terminology

Advanced sleep phase syndrome: A change in sleep dynamics in which the sleep-wake cycle is advanced in a 24-hour period.

Ambulatory sleep study or home sleep test (HST): portable system used to record multiple physiological variables during sleep.

Anticonvulsants: Drugs that prevent or reduce that severity and frequency of seizures in various types of epilepsy

Apnea: Cessation of airflow for greater than 10 seconds

Apnea index (AI): A measure of the severity of sleep apnea by tracking the number of apnea events per hour.

Apnea-hypopnea index (AHI): the number of obstructive apnea and hypopnea events per hour of total sleep period, a measure of the severity of sleep apnea

Arousal: the abrupt change from sleep to wakefulness or from a deeper to lighter stage of sleep. These changes are recorded as an increase in EEG activity (arousal). An arousal may be accompanied by increase in muscle or heart activity. A documented arousal must have duration of at least three seconds. Types of arousal are respiratory related, muscle activity or movement related, or spontaneous.

Arousal index: the number of arousals per hour of sleep period. Also called sleep fragmention.

Arousal Transient: awakening from sleep lasting  less than 10 seconds

Arrhythmia: An irregular heartbeat resulting in tachycardia or bradycardia.

Atonia: A type of temporary muscle paralysis, as seen in REM sleep

Attention deficit hyperactivity disorder (ADHD): A type of machine that monitors changes in concentrating on one thing. Variants on this disorder include hyperactivity and hypoactivity.

Auto-adjusting positive airway pressure device (APAP): A type of PAP machine that monitors changes in breathing and adjusts automatically with variable pressure flow.

Benzodiazepines: A class of tranquilizing and sedating compounds used to enhance sleep and treat movement disorders.

Bi-level positive airway pressure device (BiPAP): A PAP device that is modified to provide a lower pressure for exhalation and higher pressure for inhalation.

Body sleep posture: The four-sleep position: back (spine), left side, right side, or abdomen (prone). The time spent sleeping in each position and the number of respiratory events in a particular is recorded.

Body mass index (BMI): A measurement of body fat based on height and weight that applies to both men and women. BMI can be used to determine whether patients are overweight, obese, underweight, or normal weight. A BMI score between twenty and twenty-five is considered normal; below twenty is considered underweight; and above twenty-five is considered overweight.

Bradycardia: A heart rhythm with a rate lower than sixty beat per minute.

Bruxism: The occurrence of abnormal muscle activity involving the jaw that may be static or involve muscle movement.

Cataplexy: A sudden, dramatic decrease in muscle control and loss of deep reflexes that follows a strong emotional or physical stimulus such as laughter, surprise, or sudden physical exercise, and is one of the tetras of narcolepsy symptoms.

Central sleep apnea/hypopnea: Interruption of oral/nasal airflow not associated with respiratory effort or airway blockage; through to be related to a temporary irregularity in the brain’s control of breathing.

Cheyne-Stokes respiration (periodic breathing): An abnormal breathing pattern typified by waxing and waning fluctuations in respiratory rate and tidal volume usually

associated with congestive heart failures and neurological disease.

Circadian rhythm disorder: A change in the innate behavioral and physiological functions that affect sleeping and waking states within the twenty-four cycle.

Cone- beam computed tomography (CBCT): The use of divergent, cone-shaped imaging of the head and neck that acquired volumetric data sets of nearly six hundred distinct images. The scanning software collects the data and reconstructs it, producing three-dimensional anatomical images that can be manipulated and viewed with specialized software.

Continuous positive airway pressure (CPAP): The device used to treat sleep apnea by creating continuous, positive airway pressure to maintain an open airway, enabling normal breathing through the patient’s nose or mouth.

Craniomandiblar cervical disorder (CMCD): A musculoskeletal imbalance that causes pain in the face, jaw, and neck. This condition may be associated with abnormal muscle activity and sleep disruption. Temporomandibular joint and upper-cervical degenerative changes have been a served.

Deep sleep: Stage 3 non-REM sleep associated with delta waves on electroencephalogram (EEG) recordings.

Delayed sleep phase: the sleep period is moved back in time within the customary sleep-wake cycle, resulting in a delayed occurrence of sleep within the twenty-four-hour period.

Delta sleep: the stage of sleep in which EEG delta waves are prevalent or predominant (non-REM-sleep stage 3).

Diagnostic sleep study: Used to monitor several physiological actives while the patient sleep, it is commonly performed to determine the absence or presence of a specific sleep disorder. The sleep study may study may occur in a sleep-disorder center, or in a patient’s home using portable recording equipment

Diaphragm: The large, concave muscle attached to the rib cage at the bottom of the chest (top of the abdomen). Inhalation occurs when the diaphragm contracts and exhalation occurs when the diagram relaxes.

Diurnal: Indicates daytime activity versus nocturnal or nighttime activity.

Dopamine agonist: one of the main drugs indicated for treatment of Parkinson’s like symptoms.

Durable medical equipment (DME): Prescribed healthcare equipment including positive airway pressure machines and mandibular repositioning devices.

Drowsiness: The patient has difficulty staying awake.

Electrocardiograph (EKG): a method of recording the heart’s electrical activity that is used to document abnormal heart function including arrhythmia, tachycardia, and bradycardia.

Electroencephalogram (EEG): A method of recording the brain’s electrical that is used to document sleep stages, arousals, and awakening.

Electromyogram (EMG): A method of recording electrical activity from the muscular system that is used to document sleep stages, arousals, and awakenings. Surface electrodes are routinely places on the submental jaw area. During REM sleep, the chin EMG is topically inhibited. Electrodes may also be placed in the masseter and anterior temporalis muscle areas to record both jaw movement and muscle activity.

Electrooculogram (EOG): A recording of voltage changes resulting from shifts in position of the eyeball that is used to document sleep stages, arousals, and awakenings. Surface electrodes are placed near the eyes to record eyeball movement. Rapid eye movement characterizes the REM-sleep stage.

Epoch: A baseline thirty-second duration of a sleep recording.

Epworth Sleepiness Scale (ESS): Eight-question, self-reported survey of patient’s propensity to fall asleep during the day. A score of seven or above is considered.

Excessive daytime sleepiness or somnolence (EDS): A subjective patient’s report documenting their difficulty in staying awake during the day.

Fatigue: A feeling of tiredness or weariness during waking hours.

Fiber-optic nasopharyngoscope: A flexible foible fiber-optic scope used to examine nasal passages, nasopharyngeal, oropharynx, and laryngopharynx.

Gastroesophageal reflux disease (GERD): An abnormal flow of stomach acid upward into the esophagus associated with noxious taste, arousals, and disrupted sleep.

Genioglossus advancement: A surgical procedure for sleep apnea or snoring. A segment of mandibular symphysis containing the anterior the attachment of the genioglossus muscle is pulled forward and stabilized, posturing the tongue more forward and preventing it from blocking the airway.

Heart rate (beats per minute): the pace or speed of the heart measured in beats per minute. Sixty to eighty beats per minute is considered a normal heart rate in adults.

Hertz (Hz): A measure of sound frequency in cycles per second (cps)

HST – Home Sleep Test

Hyoid suspension: A surgical procedure used in the treatment of sleep apnea or snoring. The hyoid bone is located in the neck, anterior to the airway, muscle attachments. The hyoid bone is pulled forward and downward and is attached to the superior aspect of the thyroid cartilage, opening the airway.

Hypercapnia: An elevated level of carbon dioxide in the blood.

Hypersomnia: An excessive, prolonged duration of sleep.

Hypertension: Abnormally high blood pressure.

Hypopnea: A reduction in but not complete cessation of airflow to <50% of normal, usually in association with a reduction in oxyhemoglobin saturation

Hypoxemia: A reduced level of oxygen in the blood.

Hypoxia: Occurs when insufficient oxygen reaches the tissues of the body.

Imidazopyridines: A class of compounds used to induce sleep such as Zolidem, which goes by the trade name Ambien.

Insomnia: Difficulty falling asleep (initiation insomnia), or difficulty maintaining the sleep state (maintenance insomnia), associated with sleep loss.

Laryngopharynx: The lower portion of the pharynx extending from the tip of the epiglottis to the larynx.

Laser assisted uvulopalatoplasty (LAUP): The laser ablation of excessive palatial soft tissue used to reduce snoring and sleep apnea.

Light sleep: A term used to describe non-REM-sleep stages 1 and 2.

Light therapy: A modality used in the treatment of seasonal affective disorder (SAD). This therapy exposes the eyes to light of appropriate intensity and duration and at the appropriate time of day to affect the timing, duration, and quality sleep.

Macroglossia: An overly large tongue

Maintenance of wakefulness test (MWT): A measure of an individual’s degree of during waking hours. Maintenance of wakefulness testing is indicated when the individual’s ability to remain awake becomes a personal or professional safety issue. Mean sleep latencies that are less than eight minutes are considered abnormal.

Mandibular repositioning device (MRD): An intraoral device used to treat obstructive sleep disorders and snoring. This therapy is device is normally secured by the dentition, and designed to reposition the mandible anteriorly and vertically, bringing the tongue forward, maintaining an open airway.

Maxillomandibular orthotic (MMO): An intraoral device used to treat temporomandibular disorders. This therapy is focused on altering neuromuscular patterns, and improving area muscle and joint function. The device is designed to reposition the mandible anteriorly, laterally, vertically and in some cases, allowing rotational changes. Also called a mandibular anterior repositioning appliance (MARA) or anterior appliance (ARA).

Maxillofacial: A term that refers to the anatomical area of the middle and the jaws.

Maxillomandibular osteotomy and advancement (MMOA): A surgical procedure developed for patients with retro-lingual airway obstruction. The procedure involves the surgical fracturing and postural advancement of the maxilla and mandibular or is limited to advancement of the mandibular only.

Mixed sleep apnea: A complete absence of airway for more than seconds accompanied by a complete absence of respiratory effort (central apnea) at the beginning of the event followed by a gradual increase in effort (obstructive apnea) over time.

Movement arousal: body movement associated with arousal or awakening.

Multiple sleep latency test (MSLT): A series of nap test utilized to assess excessive daytime sleepiness (narcolepsy).

Musical tone: The amount of tension and contraction in a muscle.

Myoclonus: Muscle contractions in the forms jerks or twitches.

Narcolepsy: A sleep disorder characterized by excessive sleepiness, cataplexy, sleep paralysis, hallucinations, and a tendency to pass directly from wakefulness into REM sleep.

Nasal airflow/nasal ventilation: A pressure recording (thermistor) of the complete respiratory cycle by measuring inspiratory and expiratory airflow

Nasal speculum: A medical tool for investigating patency of the nasal airway.

Neurotransmitter: The endogenous biochemicals that are released from axon terminals of one neuron and transmit the signal to the next neuron by combining with its receptor molecules. Neurotransmitters important in the control of sleep and wakefulness include: norepinephrine, serotonin, acetylcholine, dopamine, adrenaline, and histamine.

Nocturia: Excessive, often frequent, urination during the night.

Nocturnal: The patient demonstrates high levels of during the dark, customary sleep period. See also diurnal.

Nocturnal confusion: Episodes of delirium or disorientation near or during nighttime sleep; often seen in the elderly, and patients suffering from Alzheimer’s disease.

Nocturnal penile tumescence (NPT): The hardening and expansion of the penis sleep (penile erection) associate with nocturnal arousal.

Non-REM sleep (NREM): The tree stages of sleep not characterized by rapid eye movement. These stages progress from lighter to deeper sleep (stages 1 through 3)

Obstructive sleep apnea/hypopnea: Airway blockage resulting interruption in oral/nasal airflow for 10 seconds or more, ranging from partial to full cessation of breathing accompanied by respiratory effort, arousal from sleep level, decrease in blood oxygen.

Opioids: Primary use of this category of drug is to obtuse pain with side effect of sedation.

Oral appliance therapy (OAT): Non-specific term for treatment of multiple jaw related disorders with an oral appliance.

Oxygen desaturation: A condition that reflects a decrease in the amount of oxygen of carried by hemoglobin in the blood; values below 90 percent are considered abnormal.

Oxygen saturation: A measure of the oxygen carried by hemoglobin in the blood; normal values are are 90 to 100 percent.

Oximeter (pulse): An instrument that provide estimates of arterial oxyhemoglobin saturation (SaO2) by utilizing selected wavelength of light to determine they saturation of oxyhemoglobin (SpO2). The sensor is usually attached to the finger.

Parasomnia: a category of sleep disorders that involve abnormal movements, behaviors, emotions, perceptions, and dreams that occur while falling asleep, sleeping, between sleep stages, or during arousal from sleep.

Paroxysmal nocturnal dyspnea (PND): Respirator distress and shortness of breath due to pulmonary edema that often awakens the sleeping individual.

Periodic limb movement Disorder (PLMD): A condition characterized by periodic episodes of repetitive limb movements occurring during sleep. The muscle activity and movements are associated with arousals and awakening.

PLMD index: The number of sleep-related limb movements per hour of sleep.

PLMD arousal index: The number of sleep-related limb movements per hour of sleep that are associated with an arousal (more than fifteen per hour considered significant)

Pharynx: The area posterior to the nose and the oral cavity extending from the base of the skull to the larynx that functions as the passageway for air. Also, partially used for food and. Liquid ingestion from the mouth to the esophagus.

Physical medicine: The branch of medicine that focuses on enhancing and restoring physical capabilities to those with physical impairments or disabilities.

Pineal gland: The gland in the brain that secretes the hormone melatonin.

Polysomnogram (PSG): The continuous and simultaneous recording of physiological variables during sleep. Basic physiologic measures include EEG, EOG, EMG, EKG, respiratory air flow, and limb and jaw movement. Used primarily for the diagnosis of sleep-related breathing and movement disorders.

Polysomnography:  Multichannel electrophysiological recording of electroencephalographic, electroculographic, electromyographic, ECG, and respiratory activity to detect disturbance of breathing during sleep

Positive airway pressure (PAP): A mode of respiratory ventilation used primarily in the treatment of sleep apnea. The pressure needed to maintain an open airway in a sleep apnea patient expressed in centimeter of water displacement (cm H2O). The positive pressure can range from five to twenty centimeters H2O according to patient requirements as determined by a CPAP titration study.

Radio frequency ablation (RF): A surgical procedure also known as somnoplasty for reducing nasal and oropharyngeal soft tissue thought to e involved in airway abstraction.

REM sleep: A sleep stage characterized by rapid eye movement, increased brain activity, and muscle atonia: most dreaming occurs ion this stage, which accounts for approximately 20 percent of sleep in adults.

REM motor atonia: The suppression of voluntary muscle activity during REM sleep.

Respiratory disturbance index (RDI): The total of obstructive apneas, hypopneas, and respiratory effort related arousals divided by total hours of sleep time.

Respiratory events: The total number of obstructive, mixed and, central apneas and hypopnea, plus respiratory effort-related arousals.

Respiratory effort-related arousal (RERA): Breathing disorder characterized by obstructed upper airway with airflow reduction which does not meet the criteria of apnea or hypopnea, associated with increase in respiratory effort accompanied by arousal from sleep level. deep creeping or crawling sensation in the legs that occurs when an individual is awake and sedentary. The sensations are often relived by movement.

Restless leg or limb syndrome (RLS): A sleep characterized by a deep creeping or crawling sensation in the legs that occurs when an individual is awake and sedentary. The sensations are often relived by movement.

Sagittal: The side view of the face (lateral perspective). Similar terminology for other axes of the human body would include axial for the vertical perspective and coronal for the anterior/posterior perspective. Synonyms for sagittal/axial/coronal are lateral/superior-inferior.

Septoplasty: A surgery on the nasal septum to enhance airflow.

Sleep: A state marked by lessened consciousness, lessened movement of the skeletal muscles, and slowed-down metabolism.

Sleep apnea event: A near to complete cessation of oral/nasal airflow for 10 seconds or more with an accompanying decrease in blood oxygen and arousal from sleep level.

Sleep apnea syndrome: At least 10 to 15 apneas and hypopneas per hour of sleep associated with symptoms of sleep apnea, including loud snoring, restless sleep, nocturnal dyspnea, headaches in the morning, and excessive daytime sleepiness

Sleep architecture: Non-REM-sleep stage 1-3 and REM sleep stage. These stages cycle four to six times throughout the sleep period. Of the total sleep time, 75-80 percent is typically NREM, and 20-25 percent is REM stage sleep (NREM stage 1: 10 percent; stage 2: 50 percent; stage 3: 20 percent; and REM: 20 percent total sleep time/TST).

Sleep cycle: A progression of sleep states from lighter (stage 1 and 2) to deeper sleep (stage 3) levels. Stages 1-3 are considered non-REM, and there is only one stage of REM sleep. The sleep stated continue to alternate throughout the night with an average period of about approximately 90 ninety minutes. A night of normal sleep typically consists of four to six cycles.

Sleep debt: The result of recurrent sleep deprivation that occurs over time when an individual has an insufficient amount of the restorative daily sleep that is required to feel to feel rested and refreshed.

Sleep deprivation: An acute or chronic lack of sufficient sleep.

Sleep disorders: A broad range of possible health problems arising from numerous causes including dysfunctional sleep mechanism, abnormalities in physiological functions during sleep, abnormalities of the biological clock, and disturbances that are induced by factors extrinsic to the sleep process.

Sleep efficiency (SE): The proportion of sleep during the designated sleep period; the ratio of total sleep time to total time spent in bed.

Sleep fragmentation: Clinical evidence sleep disruption with arousal occurring throughout the night, reducing the total amount of time spent in the deeper levels of sleep.

Sleep hyperhidrosis: Excessive sweating during sleep associated with hormonal changes; the condition may be responsible for arousals.

Sleep hypopnea event: A partial interruption oral/nasal airflow for ten seconds or more with an accompanying decrease in blood oxygen and arousal from sleep level.

Sleep latency: The time period measured form actual bedtime to the beginning of the sleep state. Used to support diagnoses of narcolepsy (excessive daytime sleepiness), EDS, cataplexy, hypnagogic hallucinations, and sleep paralysis.

Sleep meditations: The thoughts, feeling, images, perception, hallucinations, and active dreams occurring during sleep that may diminish the quality of sleep.

Sleep-related breathing disorders (SRBD): The term refers to the spectrum of breathing anomalies ranging from chronic or habitual snoring to upper airway resistance syndrome to and obstructive sleep apnea.

Sleep stages: Sleep stages are cyclical rather than Lin are. Sleep begins in 1 and progresses into stages 2 and 3. After stage 3 sleep, stage 2 sleep may be repeated before entering REM sleep. Once REM sleep is over, the body usually returned to stage 2 sleep. Sleep cycles through these stages approximately four or five times throughout the night. On average, we enter the REM stage approximately ninety minutes after falling asleep. The first cycle of REM sleep might last only a short amount of time, but each becomes longer. REM sleep can last up to an hour as sleep progresses.

Sleep stage 1: The beginning of the sleep cycle: a relatively light stage of sleep. Stage 1 can be considered a transition period veteran wakefulness and sleep. In stage 1, the brain produces high amplitude theta waves, which are very slow brain waves. This period of sleep lasts approximately 5 percent of total sleep time.

Sleep stage 2: The second stage of sleep for approximately twenty minutes. The brain begins to produce busters of rapid, rhythmic brain wave activity known as sleep spindles. Body temperature decreases and heart rate slows. This period of sleep lasts approximately 50 percent of total time.

Sleep stage 3: This stage was previously divided into stages 3 and 4. Deep slow brain waves known as delta waves emerge during stage 3 sleep; this stage is sometimes referred to as delta, or slow-wave, sleep. During this stage, people become less responsive and noises and activity in the environment may fail to generate a response. It also acts as a transitional period between light sleep and very deep sleep. Bed-wetting and sleepwalking are most likely to occur at the end of this stage of sleep. This sleep period comprises approximately 25 percent of total sleep time.

Sleep stage REM: Most dreaming occurs during the fourth stage of sleep, known as rapid eye movement (REM) sleep. REM sleep is characterized by eye movement, respiration rate, and increase brain activity. REM sleep is also referred to as paradoxical sleep because while activity in the brain and other body systems increase, the muscles become more relaxed. Dreaming occurs, along with increased brain activity and paralysis of voluntary musculature. Stage REM is approximately 20 percent of total time.

Snoring: The sound produced by the vibration of respiratory structures as a result of obstructed air movement during the sleep period.

Stanford sleepiness Scale (SSS): Rating scale consisting of seven numbered statements describing subjective levels of sleepiness and alertness.

Temporomandibular disorder (TMD): A musculoskeletal imbalance involving the joints and surrounding musculature. Symptoms vary from jaw-area discomfort to jaw-joint noises and restricted muscle activity. TMD is often found as a comorbidity in obstructive sleep apnea patients. Abnormal muscle activity with clenching, excessive jaw movement, and disruption has been observed.

Temporomandibular joint (TMJ): The billable articulation between the base of the skull and the mandible. A diarthrodial joint that allows both rotational and translational function.

Tongue-retaining device (TRD): A pliable intraoral device that holds the tongue forward using a tongue compartment and suction. The device has been used on patients who are edentulous, who have a limited range of motion. This appliance is jot appropriate for mouth breathers.

Total sleep time (TST): The amount of actual sleep time within a sleep period, calculated by total sleep period less arousal and waking time.

Tracheotomy: A surgical procedure that creates an open in the trachea so that the patient can breathe.

Tracheostomy: The actual opening in the trachea that is created by surgery. This opening is normally enhanced with plastic tubing.

Tricyclic antidepressants: A medication for the treatment of depression and to control cataplectic attacks, hypnagogic hallucinations, sleep paralysis. Most tricyclic antidepressants also reduce REM sleep.

Turbinates: The small, shelf -like cartilaginous structures covered by mucous membranes that protrude into the nasal airway to help warm, humidify, and cleanse inhaled air on its way to the lungs.

Upper airway resistance syndrome (UARS): Apart of the spectrum of obstructive sleep-related breathing disorders in with repetitive increases in resistance to airflow in the upper airway lead to lead to arousals and daytime fatigue. Apneas and hypopnea may be totally absent. Blood-oxygen levels can be the normal range.

Uvula: The small, soft structure hanging from the bottom of the soft in the midline above the back of the tongue.

Uvilopalatopharyngoplasty (UPPP): Surgery to reduce the tissue of the soft palate, uvula, and pharyngeal tonsil area.