Sleep Medicine Acronyms (From APAP to Zzzz): Part 2, E-M


It can be frustrating trying to understand medical jargon of any kind. Sleep medicine acronyms are no exception.

Here is a series on abbreviations you are likely to encounter during your visits to a sleep specialist or sleep center. 

This second section highlights terms that start with the letters E through M.

See also: 

Sleep Medicine Acronyms (E-M)




Electrocardiogram. A medical device which measures heart rhythm, rates, and activity. Using ECG during a sleep study helps to confirm sleep stages, tracks cardiac activity during sleep, and records the presence of arrhythmias. Sensors are applied to the chest and ribcage.


Excessive Daytime Sleepiness. The experience of extreme fatigue during waking hours which can interfere with the activities of daily living.  Learn more: 


Electroencephalogram. A medical device which measures brain wave activity through the application of electrodes to the scalp. Using ECG helps to confirm sleep stages, identifies seizure activity during sleep, and records the presence of neurological dysfunction during sleep. Learn more: 


Electromyogram. A medical device which measures muscle activity. Using EMG helps to confirm sleep stages and identifies key symptoms for specific sleep disorders. Sensors are applied to the legs and chin and sometimes the arms. Learn more: 


Electro-oculogram. A medical device which measures eye movement. Using EOG helps to confirm sleep stages. Sensors are applied to the face near the eyes. Learn more: 


Expiratory Positive Airway Pressure. While using PAP therapy, EPAP is the measurement of positive airway pressure that is applied during exhalation. In CPAP, EPAP is the same with both inhale and exhale; with BiPAP, the EPAP is delivered at a lower pressure. Learn more: 


Epworth Sleepiness Scale. A questionnaire that all sleep patients fill out which helps to assign severity to their overall sense of sleepiness during the day. 



Gastroesophageal Reflux Disease. Also commonly referred to as acid reflex or heartburn, this is a condition in which the valve that separates the esophagus from the trachea—to prevent food particles and stomach acid from entering the airway—loses its tone or otherwise malfunctions. Learn more: 




Home Sleep Apnea Test. This portable sleep test is used in the home for one or more nights to ascertain whether a patient is at high risk for sleep apnea. It is also referred to as HST. Learn more: 



International Classification of Sleep Disorders, Third Edition. This is the authoritative clinical reference used for diagnosing sleep disorders.


Inspiratory Positive Airway Pressure. While using PAP therapy, IPAP is the measurement of positive airway pressure that is applied during inhalation. In CPAP, IPAP is the same with both inhale and exhale; with BiPAP, the IPAP is delivered at a higher pressure. Learn more: 




Maxillomandibular Advancement. This refers to technology applied by certain oral devices used to treat snoring, upper airway resistance, and obstructive sleep apnea. These mouthpieces advance the lower jaw as the wearer sleeps, allowing the airway to keep its tone and preventing its collapse. Learn more: 


Multiple Sleep Latency Test. This refers to a specific kind of sleep test which is used to identify and diagnose certain kinds of hypersomnias, such as narcolepsy. Learn more: 


Maintenance of Wakefulness Test. This refers to a specific kind of sleep test which is used as a public safety precaution to assess daytime sleepiness in workers who operate vehicles or heavy machinery.  It is also used to measure effectiveness of PAP therapy in new sleep apnea patients.  Learn more: 

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