Sleep Dictionary

Apnea:  A cessation of breathing for 10 seconds or more; derived from the Greek word “without breathing”.  Apneas that occur during sleep deprive the body of oxygen and disrupt the normal sleep cycle.

Apnea/Hypopnea Index (AHI):  A measure of the severity of sleep apnea.  The average number of apneas and hypopneas per hour of sleep.

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

Auto-CPAP:  Therapy option for treatment of sleep apnea where the machine “auto” adjusts to the level of pressure needed to overcome an obstruction in the upper airway.

Bi-Level therapy (BIPAP):  Therapy option for treatment of sleep apnea where both an inspiratory and expiratory pressure are prescribed.

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 the stop breathing for 10 seconds or longer.

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

Continuous Positive Airway Pressure (CPAP):  A 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.

CPAP Pressure:  The air pressure needed by an OSA patient to maintain an open airway during sleep.  Expressed in centimeters of water pressure (cm H20)

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

Electromyogram (EMG):  A recording of the electrical activity of a muscle.  Use 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 use 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 a person on Bi-level positive airway pressure, where a patient inhales at a higher pressure compared to the exhalation pressure.  Bi-level therapy is another form of PAP therapy for sleep apnea.

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

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

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

Inspiratory Positive Airway Pressure (IPAP):  Pressure prescribed for the inspiratory phase of a person on Bi-level positive airway pressure.  Bi-level is another form of PAP therapy for sleep apnea.

Mandibular-Maxilary 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.  The test will monitor the chance to fall asleep at different times throughout the day when they would normally be awake.  People who fall asleep in less then 5 minutes are likely to require some type of treatment for sleep disorders.

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

Oral Appliances:  Dental appliances molded to fit over the teeth.  This appliance is worn at night and prevents the lower jaw from falling back against the throat during sleep.

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.

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

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

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

Uvulopalatopharyngoplasty (UPPP):  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.

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