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Sleep Medicine Acronyms (From APAP to Zzzz): Part 1, A-D

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

This first section highlights terms that start with the letters A through D.

Sleep Medicine Acronyms (A-D)



Apnea Hypopnea Index. A metric used to measure the severity of sleep apnea. It is based on the total number (per hour) of complete obstructions (apnea) and partial obstructions (hypopnea) in breathing, expressed as an average.


Automatic Positive Airway Pressure or Auto-Titrating Positive Airway Pressure or AutoPAP . This therapy, used for treating sleep apnea, provides a preset range of therapeutic air pressure for the user.


Adaptive Servo Ventilation. This form of noninvasive ventilation is used to treat sleep apnea when it occurs in conjunction with other serious health problems.


Alert, Wakeful, and Keeping Energetic. There are A.W.A.K.E. support groups all over the United States which exist to help people with sleep apnea and other sleep disorders to succeed with therapy.



Bilevel Positive Airway Pressure. BiPAP is a trade name, whereas BPAP is a generic acronym. However, BiPAP is frequently used to refer to this kind of PAP therapy, which offers two modes of pressurized air: one for the incoming inhale (IPAP), and another for the outgoing exhale (EPAP).


Body Mass Index. This is the number derived from a formula using your height and weight measurements to determine whether you are overweight or obese.



Continuous Positive Airway Pressure. This “gold standard” therapy for treating sleep apnea uses a single delivery of pressurized air to “splint open” the upper airway during sleep.


Central Sleep Apnea or Central Sleep Apnea Syndrome. Central sleep apnea is different from obstructive sleep apnea in that the failure to inhale and exhale adequately during sleep is caused by faulty mechanisms in the brain (the central nervous system).


Cheyne-Stokes Breathing or Cheyne-Stokes Respiration. A distinctive “crescendo-decrescendo” breathing pattern (also referred to as “periodic breathing”) found in people with central sleep apnea. It is common in patients with congestive heart failure.



Durable Medical Equipment. This refers to all the different components of sleep apnea therapies (PAP machine, mask, filters, tubing, chin supports, etc.). DME is also frequently used to refer to the sleep specialists who provide support for patients using DME.


Delayed Sleep Phase Disorder/ Delayed Sleep Phase Syndrome. The syndrome refers to circadian rhythms that run 2 to 4 hours later than average; people with DSPS consider themselves “night owls.” The disorder refers to those who suffer significant problems living with delayed sleep phase, such as job stress and relationship strain.

Further Reading

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