If you've just been diagnosed with sleep apnea, your doctor is likely recommending that you use a CPAP machine while you sleep — even if you're just napping. As health devices go, this might not be one you're too familiar with. Or perhaps you've never even heard of CPAP machines.

"Sleep apnea is when a person repeatedly stops breathing for a brief period while sleeping, either because the throat closes when it shouldn't — obstructive sleep apnea — or due to a change in breathing rhythm or control, as is the case with central sleep apnea," explains Dr. Aarthi Ram, a neurologist specializing in sleep medicine at Houston Methodist. "A CPAP machine works to prevent apnea episodes during sleep, and it's a first-line treatment option for both types of sleep apnea."

How does a CPAP machine facilitate proper breathing? Dr. Ram is here to answer that question, as well as five more questions commonly asked about sleep apnea machines.

What is a CPAP machine?

CPAP stands for continuous positive airway pressure. A CPAP machine, then, is a way of generating and delivering this positive airway pressure. In the case of sleep apnea treatment, it's a form of non-invasive ventilation that helps keep your airway from collapsing while asleep.

"The positive pressure delivered into your airway acts as an air stent that keeps the airway open, even during an apnea episode," explains Dr. Ram. "The user wears a mask over their nose, or nose and mouth, which is connected to the CPAP machine by a hose. The air is pushed through the hose and into the person's airway to keep the airway open."

It's one of the most effective ways to prevent apnea events and, as such, it's also the most commonly prescribed sleep apnea treatment option.

"Some patients find wearing the mask for a full night uncomfortable," adds Dr. Ram. "But your sleep specialist should work with you to find a mask and machine that you are comfortable wearing and using all night."

To that end, most of today's CPAP machines are relatively quiet, and a variety of mask options are available if comfort or fit is an issue. Continued follow-up with your doctor can help ensure you're using the most effective treatment as machine and supply technology improves.

Why do I need a CPAP machine?

Even if apnea events don't wake you up, the abnormal breathing affects your sleep quality, leading to symptoms like daytime sleepiness, difficulty concentrating and waking up with headaches.

There are long-term consequences to consider, too.

"Because sleep apnea can deprive the body of oxygen — your brain and heart included — sleep apnea affects your overall health," says Dr. Ram.

Left untreated, sleep apnea can increase the risk of a number of health conditions, including:

• High blood pressure
• Heart attack
• Arrhythmia
• Stroke

By delivering positive airway pressure, a CPAP machine keeps your airway open, even during an apnea event — ensuring that your brain, heart and other organs receive a continuous supply of oxygen. This reduces both the number of times you stop breathing while asleep and your risk of apnea's long-term health consequences.

Is there a best CPAP machine?

There are many different kinds of CPAP machines available, so you're likely wondering which one you should choose. Some options offer enhanced comfort and convenience, but the type of machine and mask you need will likely depend on the type and/or severity of the sleep apnea you have.

"Some CPAP machines deliver a fixed pressure, while others have a self-adjusting pressure feature," explains Dr. Ram. "An option with adjustable pressure is called an Auto PAP, a 'smart' machine that uses an internal algorithm to adjust the pressure delivered based on the person's needs."

Humidity control, which allows the user to adjust the level of moisturized air delivered, is another helpful setting included in some CPAP machines. This can help with dry mouth, a common sleep apnea symptom.

Several types of CPAP masks are available — some cover just the nose, others cover both the nose and mouth. Some new machines also feature a top-of-head connection for tubing, allowing for more freedom of movement while asleep.

"All of the available features and functions should be discussed with your sleep specialist to determine what makes the most sense for you, specifically," says Dr. Ram. "The best CPAP machine is the one you will actually use throughout sleep — every sleep, even napping. But, depending on sleep apnea type or severity, some people may require certain functions be included for effective control of apnea events."

CPAP vs. BiPAP: What's the difference?

Speaking of how your specific diagnosis might influence which machine is right for you, what's the difference between CPAP and BiPAP?

"BiPAP stands for bilevel positive airway pressure, meaning it delivers two pressures as opposed to the single pressure delivered by a CPAP," explains Dr. Ram. "Of the two pressures, one is used when you inhale and the other, a lower pressure, is used when you exhale."

Dr. Ram adds that, due to the lower pressure on exhalation, some people find using a BiPAP machine more comfortable. Additionally, the results of your sleep study might suggest a BiPAP machine to be a better fit for you.

"For someone who has hypoventilation — an elevation in carbon dioxide — a BiPAP may be what's prescribed," adds Dr. Ram.

How do you get a CPAP machine?

A prescription, only issued following a sleep study and official diagnosis of sleep apnea, is needed to get a CPAP machine.

"As mentioned, people often require a specific machine and specific settings," says Dr. Ram. "A prescription helps ensure that the right device and equipment are being used. The goal is to prevent apneic episodes, so we need figure out the optimal pressure for you."

A prescription also means some of the cost of a CPAP machine and supplies can be covered by insurance.

How much is a CPAP machine?

CPAP machines can range from $700 to over $1,000. And CPAP supplies (masks and tubing) can range from $50 to $150.

"The price will often depend on the brand and model," says Dr. Ram. "Just like smartphones, there are newer versions and older versions."

Prices have increased over the last few years due to supply chain issues, in part caused by a recall that increased the demand for CPAP machines as people searched for a replacement.

How much of the cost will you pay versus how much will your insurance company cover? That varies by provider, policy, state, exact diagnosis and more. Call your insurance provider for clarity around what they'll pay and what you'll owe.