Sleep Dictionary - Medical Terms

Sleep Dictionary

• Apnea: A cessation of breathing for 10 seconds or more; derived from the Greek word meaning “without breathing.” Apneas may occur more than 20 times per hour and keep the brain on alert, preventing the body from resting effectively.


• Apnea/Hypopnea Index (AHI): A measure of the severity of sleep apnea, as determined by the number of apneas and hypopneas experienced per hour of sleep.


• Atrial Fibrillation: An irregular heartbeat as a result of abnormal electrical impulses causing the atria (upper chambers of the heart) to quiver. A person suffering from atrial fibrillation is twice as likely to suffer from sleep apnea.


• Cardiovascular Disease: A class of medical conditions that affect the structure and function of the heart, including coronary artery disease, heart failure and abnormal heart rhythms. Cardiovascular disease is the leading cause of death in the United States for both men and women.


• Central Sleep Apnea: A condition that occurs during sleep when a person’s brain fails to send electrical signals to the muscles that control breathing, causing the person to cease breathing for 10 seconds or longer.


• Compliance: The extent to which a person follows a treatment regimen such as CPAP.


• Continuous Positive Airway Pressure (CPAP): A breathing device that delivers pressurized air at a constant and continuous pressure to splint the airway open. This therapy treats sleep apnea by preventing the tissues in the airway from collapsing, allowing the person to breath continuously.


• CPAP Pressure: The air pressure needed by an OSA patient to maintain an open airway during sleep.


• Electroencephalogram (EEG): A recording of the electrical activity of the brain during sleep. Used to determine the quantity and quality of sleep.


• Electromyogram (EMG): A recording of the electrical activity of a muscle. Used to help identify rapid eye movement sleep.


• Electro-oculogram (EOG): A recording of the movement of the eyes. Used to identify rapid eye movement stage of sleep.


• Epworth Sleepiness Scale: A subjective test used to determine how sleepy a person is.


• Expiratory Phase: The phase of a breathing cycle when air is exhaled.


• Expiratory Positive Airway Pressure (EPAP): Pressure prescribed for the expiratory phase of an individual on Bi-level positive airway pressure (PAP) therapy where a patient inhales at a higher pressure compared to the pressure present when they exhale. Bilevel therapy is another form of PAP therapy for obstructive sleep apnea.


• Fiber-optic Pharyngoscopy: A procedure used to determine airway collapsability. A flexible tube is placed through the nose to the throat while a camera at the end takes pictures of the breathing area.


• Hypertension: High blood pressure. A person suffering from sleep apnea has an increased risk of developing hypertension.


• Hypopnea: A reduction in the size of a breath taken lasting 10 seconds or more, derived from the Greek term meaning “under-breathing”.


• Inspiratory Phase: The phase of a breathing cycle when air is inhaled.


• Inspiratory Positive Airway Pressure (IPAP): Pressure prescribed for the inspiratory phase on a Bi-level positive airway pressure (PAP) therapy where a patient inhales at a higher pressure compared to the pressure present when they exhale., Bilevel therapy is another form of PAP treatment for obstructive sleep apnea.


• Mandibular Maxillary Advancement: A surgical procedure that corrects facial abnormalities or throat obstructions that contribute to sleep apnea.


• Mixed Sleep Apnea: A combination of central and obstructive sleep apnea.


• Multiple Sleep Latency Test (MSLT): A test that determines how quickly a person falls asleep during the day. Patients are given the chance to fall asleep at different times throughout the day when they would normally be awake. Individuals who fall asleep in less than 5 minutes are likely to require some type of treatment for sleep disorders.


• Obstructive Sleep Apnea (OSA): A condition that occurs during sleep when a person stops breathing for 10 seconds or longer as a result of blockage in the airway that prevents air from getting to the lungs.


• Polysomnography (PSG): A sleep study to diagnose sleep disorders, including sleep apnea, by providing extensive information about a person’s physiological activity during sleep. PSG records a variety of information including the electrical activity of the brain (EEG), eye movement (EOG), muscle activity (EMG), heart rate, respiratory effort, air flow, and blood oxygen levels.


• Pulmonologist: A physician specializing in caring for patients with breathing disorders.


• Rapid Eye Movement (REM) Sleep: A deep stage of sleep recognized by a distinct EEG pattern and quick movement of the eyes associated with dreaming


• Sleep Apnea: A cessation of breathing for 10 or more seconds during sleep.


• Sleep-disordered Breathing (SDB): A general term used to describe breathing problems that occur during sleep. Sleep-disordered breathing includes three types of sleep apnea – obstructive, central and mixed.


• Somnoplasty: A procedure that uses low levels of radiofrequency energy to treat certain sleep disorders.


• Uvula: The soft tissue that hangs down at the back of the soft palate that may contribute to airway blockage in some OSA sufferers.


• Uvulopalatopharyngoplasty (UPPP or UPP or UP3): A surgical procedure that removes the soft tissue on the back of the throat and palate, thereby increasing the width of the airway at the throat opening; has a curative rate of less than 50 percent.