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What Does CPAP Mean, and What Does it Do?

Around 6 million people in the U.S.1 have been diagnosed with sleep apnea, which is a disorder that affects breathing during sleep. It’s often caused by muscles around the throat relaxing while sleeping, which narrows the airway, leading to interruptions in breathing2 and nighttime awakenings from a lack of sufficient oxygen. 

Depending on the severity of someone’s sleep apnea, their doctor or a sleep specialist may prescribe CPAP treatment. If your doctor has brought up the possibility of CPAP, it’s understandable you might have some questions about it. In this article, we’ll help you understand what CPAP entails, how it works, the benefits, and more.

What Is CPAP?

CPAP stands for continuous positive airway pressure. It’s a type of positive airway pressure (PAP) treatment that helps keep a patient’s airways open to reduce sleep apnea symptoms and help them breathe more normally. 

CPAP involves air being delivered to the patient’s airways at a pre-programmed pressure level that remains the same3 throughout the night. This air comes from a machine that’s connected to a hose and mask.

CPAP machines are used in the treatment of obstructive sleep apnea, which is a form of sleep apnea when the muscles around your windpipe relax during sleep, causing them to block your airway4. When this happens, the sleeper can’t get enough air. The brain then detects a drop in oxygen levels, it momentarily wakes the sleeper just enough to replenish their oxygen levels. These awakenings can occur multiple times throughout the night. 

While CPAP could help manage sleep apnea symptoms, important to note that CPAP does not cure sleep apnea5.

Who May Benefit From Using A CPAP?

A CPAP is often used to treat obstructive sleep apnea. However, it can also be used to assist breathing in premature babies6 who are born with underdeveloped lungs. CPAP is also used in the treatment of hypoxic respiratory failure in patients with congestive heart failure who don’t have enough oxygen in their blood.1

Who May Not Benefit from CPAP?

CPAP therapy may not be suitable for people with facial trauma or burns, where it might be uncomfortable to wear a mask. It also may not be recommended for those who have had facial, esophageal, or gastric surgery, or for patients experiencing severe vomiting.1 

Research7 suggests that CPAP may not be effective in very elderly patients who have been diagnosed with moderate to severe obstructive sleep apnea. 

In some cases, obstructive sleep apnea occurs when a person is overweight or obese, as excess fat in the upper respiratory tract can narrow the airway, causing issues with breathing.4 In this instance, lifestyle changes may be suggested before CPAP therapy to see if weight loss alleviates sleep apnea symptoms.

CPAP Machines 

A CPAP is a type of PAP machine that delivers a continuous stream of pressurized air to the patient to help keep their airway open to breathe more normally. The device consists of a small, motorized unit (which contains a filter, and often a humidifier), a flexible hose, and a mask. Patients are usually prescribed the device for at-home, nightly use. The machine draws in air from the room, filtering it and pressurizing it, before delivering it through the tubing and mask into the sleeper’s nose and/or mouth.

CPAP Masks 

There are different options available for CPAP masks, but typically, your doctor will decide which type you should get based on your needs.

  • Nasal pillow mask – A nasal pillow is a small mask that sits under the nostrils, with soft inserts that seal into the nostrils to deliver air via the nose. They’re the least cumbersome option and may be a good choice for those with facial hair that hinders the use of larger masks, or for people who feel claustrophobic wearing larger styles of mask. 
  • Nasal masks – Nasal CPAP masks seal around the entire nose and are often prescribed for people who need a higher air pressure setting or who move around frequently while sleeping. 
  • Full face masks – Full face CPAP masks are the largest type of CPAP mask, sealing around both the nose and mouth. These can be useful for patients who breathe through their mouth while sleeping.
  • Hybrid masksHybrid CPAP masks often combine elements from the nasal pillow mask and the full face mask. They usually cover the mouth, and then at the nose, they lie beneath it with two nasal pillows.

Other CPAP Equipment 

  • Chinstraps – A CPAP chinstrap is a fabric strap that sits around the chin to gently keep the mouth closed to prevent mouth breathing during CPAP treatment. 
  • CPAP pillows – CPAP pillows are special pillows that are designed to be used while sleeping with a CPAP machine. Some people struggle to sleep with their CPAP device, and regular pillows may be uncomfortable to sleep on while wearing a mask. CPAP pillows are designed to better accommodate masks and tubing. 

Learn more: Tips for Sleeping Better with CPAP

  • Tubing – The tubing, or hose, is what connects the CPAP machine to the mask. Hoses are typically 6 feet long, though some manufacturers may provide longer or shorter ones as well. 
  • Humidifiers – Humidifier tanks can help moisturize the air that comes through the CPAP machine to prevent dryness in the nose or mouth. These are usually filled with distilled water and either sit externally or are built into the CPAP machine.

Other PAP Devices

Along with CPAP, there are other types of PAP machines available. However, each one works in a slightly different way, and your doctor will advise which one is best suited for your individual needs.


An automatic positive airway pressure (APAP) machine delivers air through a tube and mask in the same way as a CPAP, but while a CPAP is programmed at a fixed pressure, an APAP changes pressure8 throughout the night based on the patient’s breathing patterns. The machine will increase pressure if it senses that you’re not breathing properly and decrease pressure when it detects normal breathing. The pressure stays the same for the inhale and the exhale.8

Who May Benefit from APAP?

Like CPAP, APAP therapy is used to treat obstructive sleep apnea. APAP may be prescribed for patients who experience apnea in different sleep stages or sleeping positions9, or who find the fixed pressure of a CPAP device uncomfortable. 

Who May Not Benefit from APAP?

APAP can sometimes cause people to wake up more in the night if they’re sensitive to frequent changes in air pressure10. In this instance, a fixed-pressure CPAP device may be more suitable. 

More Info: APAP vs. CPAP


BiPAP stands for bilevel positive airway pressure. The machine is programmed to deliver two fixed levels of air pressure11 – a higher pressure for inhalation and a lower pressure for exhalation. The pressure levels will be calibrated by your healthcare provider. 

Who May Benefit from BiPAP?

People with obstructive sleep apnea who have problems breathing out against the fixed pressure of a CPAP may benefit from the dual pressure of a BiPAP12. BiPAP may also be the preferred choice for patients who require higher air pressures13

Like APAP, BiPAP may be used for patients with more complex sleep apneas, or who aren’t finding a CPAP device effective. It’s also used to treat central sleep apnea14, which is when the brain doesn’t send the correct signals to the muscles that control breathing. BiPAP may also be used for the treatment of chronic obstructive pulmonary disease (COPD), heart failure, and hypercapnic respiratory failure.11

Explore our picks for the Best BiPAP machines here.

Who May Not Benefit from BPAP or BiPAP?

BiPAP machines are usually more expensive than CPAP machines15 due to their complexity, so they don’t tend to be prescribed to people with obstructive sleep apnea who haven’t already tried a CPAP. 

More Info: BiPAP vs. CPAP

Frequently Asked Questions

What does CPAP stand for?

CPAP stands for continuous positive airway pressure. This form of sleep apnea treatment involves a steady stream of pressurized air being delivered to your airways from a CPAP machine, which consists of a motorized unit, a hose, and a mask.

Is sleep apnea dangerous?

Yes, sleep apnea can be dangerous if left untreated. As well as extreme fatigue, sleep apnea can cause life-threatening conditions, such as heart failure and arrhythmia.3 Arrhythmia is an irregular heartbeat, and severe arrhythmia can lead to sudden cardiac death.3

What is a CPAP machine?

A CPAP machine is a device commonly prescribed by doctors to treat sleep apnea. The machine draws air in from the room and filters it, before sending a continuous flow of pressurized air through a tube and mask into the user’s airway to foster better breathing. It’s often used to help alleviate symptoms of obstructive sleep apnea.

Lisa Bowman

Lisa Bowman


About Author

Lisa is a content writer for Sleep Advisor, which combines two of her greatest passions – writing and sleeping. She can also be found writing about fitness, sustainability and vegan food.

Combination Sleeper


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