CPAP masks for side sleepers (and stomach sleepers): what changes

By SnorkelMatch, last checked October 10, 2026. How we check

Lying on your side puts a pillow against one edge of your mask. A mask that seals well when you sit up can then shift or leak. This page does not pick a mask for you; it explains what changes on your side or your stomach, what the makers say to check, and which mask types to ask your supplier about.

Open the fit finder

Fig. 1Two heads lying on their side, each wearing a nasal mask. Left: a flat pillow presses on the lower edge of the cushion and air escapes there. Right: a pillow with a cut-out leaves room for the mask and hose.

Why a mask that seals sitting up can leak on your side

Most people try a mask on sitting up, in front of a mirror. ResMed’s fitting page warns that “a mask that fits well when you’re sitting up might not fit so well when you’re lying down”, because facial muscles change when you lie down and relax further when you are asleep^[1]. Fisher & Paykel lists sleep position, with breathing style and facial features, among the things that “can change the fit and seal of your mask”^[2].

On your side there is also the pillow. It pushes on the cushion or the frame, and if one edge lifts, air escapes there (Fig. 1). The American Academy of Sleep Medicine (AASM) explains why that matters: “The mask must make a seal in order to keep your airway open through the night.”^[3]

The reflex is to tighten the straps. Fisher & Paykel cautions that “a too-tight mask can distort the shape of components and cause leaks”^[2], and ResMed says your mask “should be as loose as possible while still creating a seal”^[1].

How to fit the mask lying on your side

Loosen the straps, place them over your head and tighten them gradually^[2].
Adjust the straps evenly on both sides^[4]. Fisher & Paykel suggests checking in a mirror that the headgear is set the same on each side^[2].
Check that you can get one finger under each strap, and loosen if necessary^[2].
Lie down on your usual pillow, in your usual position, and make the final adjustments there. ResMed: “you should fit your mask in your usual sleeping position”^[1]. Fisher & Paykel’s troubleshooting guide says to “test how it feels while lying in the position you normally sleep in”^[5].
If air leaks at the bridge of the nose, the eyes or the lip, ResMed’s guide suggests gently pulling the cushion away from the face to reinflate it and repositioning the mask; if a leak persists, it points to the top straps for a leak in the eyes and the bottom straps for a leak on the lip^[4].

Our leak guide goes through the other causes, and the marks guide covers red lines from straps that ended up too tight.

Mask types that leave less for the pillow to push on

The less of the mask there is on the side of your face, the less the pillow has to press on. In an article on pressure marks, Fisher & Paykel suggests considering masks with “a smaller footprint on your face, such as a nasal mask and nasal pillows mask”^[6]. Its article on nasal masks says you may prefer one if you “prefer to sleep on your side” or are an active sleeper^[7].

Fig. 2The four mask types on the same face. Nasal pillows sit at the nostrils and the nasal mask covers the nose; the full face cushion covers the nose and mouth; the under-the-nose full face covers the mouth and seals under the nose.

Sleeping position is only one factor. Nasal pillows and nasal masks are nose-only, and Fisher & Paykel notes that mouth breathers can get air in the stomach with nasal masks^[5]. If your mouth opens at night, read our guide for mouth breathers before you weigh footprint. The mask types guide compares all four, and the fit finder weighs sleeping position together with breathing, facial hair and glasses. You can also take the mask quiz, one question at a time.

Pillows and the hose

The AASM suggests you “try using a special bed pillow that is shaped for a CPAP mask and tubing”^[3]: the cut-out leaves room for the mask, as in Fig. 1. It also notes that the tubing “is long enough to allow you to move around or turn over in your bed”^[3]. Run it so that turning over does not pull on the mask, and recheck the fit if you change pillows.

If you sleep on your stomach

None of the official sources we read names a mask type for stomach sleepers, so we will not either. The geometry is simple: face down, more of the mask and frame presses into the pillow than on your side. A smaller footprint leaves less to press^[6], but the same breathing question applies. Fit the mask lying the way you actually sleep^[1], and ask your supplier which types to try.

When your provider recommends side sleeping

Side sleeping is sometimes part of the treatment plan rather than a habit. The National Heart, Lung, and Blood Institute (NHLBI) notes that “your provider may also recommend that you sleep on your side — not on your back”^[8]. That is your provider’s call, not ours.

If your mask does not stay on, does not fit well or leaks air, the NHLBI says to talk to your provider, who “may ask you to try different masks or nasal pillows”^[9]. Take a note of how you sleep and where the mask leaks; it makes that conversation shorter.

Questions people ask

What is the best CPAP mask for side sleepers?

There is no single answer: Fisher & Paykel’s fitting article says there is no one mask that is best for everyone. Types with a smaller footprint, the nasal mask and nasal pillows, leave less for the pillow to push on, and Fisher & Paykel lists side sleeping among the reasons people prefer a nasal mask. If you breathe through your mouth, that changes the picture, so take both facts to your supplier.

Why does my CPAP mask leak when I sleep on my side?

The pillow can push the cushion or frame and lift one edge of the seal, and ResMed notes that a mask that fits sitting up may not fit as well lying down because facial muscles relax. Refit the mask lying in your usual position, with the straps adjusted evenly. If it keeps leaking, talk to your supplier.

Can you use a full face mask if you sleep on your side?

Nothing in the makers’ guides we read rules it out. A full face cushion is the largest of the types, so more of it meets the pillow, which makes the final fit lying on your side and a pillow with room for the mask worth checking. If leaks continue, ask your supplier about the options.

What CPAP mask works for stomach sleepers?

None of the official sources we read names a type for stomach sleeping. Face down, more of the mask presses into the pillow, so a smaller footprint leaves less to press, but how you breathe matters too. Fit the mask lying the way you sleep and ask your supplier which types to try.

Do I need a special CPAP pillow?

It is not required. The American Academy of Sleep Medicine suggests you can try a bed pillow shaped for a CPAP mask and tubing, which leaves room for the mask when you lie on your side.

Sources

[1]
ResMed (manufacturer): CPAP mask template and size guide
"The use of these templates is not intended to replace the advice of a medical professional, sleep technician or equipment supplier."; "ensure you are printing at the actual size by turning off all page scaling"; "If you can only get a good seal by tightening the mask until it's uncomfortable, then you may have the wrong size of mask."; "sizing across different masks is not always the same"; "a mask that fits well when you're sitting up might not fit so well when you're lying down"; "you should fit your mask in your usual sleeping position"; "Your mask should be as loose as possible while still creating a seal." Read on 2026-10-10.
[2]
Fisher & Paykel Healthcare (manufacturer): How do I fit my CPAP mask correctly?
"Your breathing style, sleep position and facial features can change the fit and seal of your mask."; "Aside from nasal pillows, most CPAP masks come with sizing guides"; "Loosen the straps, place them over your head and then tighten them gradually."; "Check that you can get one finger under each strap – loosen if necessary."; "Lie in your preferred sleeping position to make final adjustments."; "A too-tight mask can distort the shape of components and cause leaks."; "Use a barrier on your skin ... a barrier cream, mask liner or gel pad"; signs of a poor fit: air "around your eyes, nose or mouth", noise, pain, "excessive lines, red marks or bruises"; "A nasal mask could be the best option if you breathe through your nose during sleep."; "There's no one mask that's best for everyone."; a full-face mask has "straps typically around your head and chin"; a noisy mask "can be a sign of an insecure seal and air draft"; "ensure that the headgear is adjusted to the same setting on each side" Read on 2026-10-10.
[3]
American Academy of Sleep Medicine (AASM), Sleep Education: Continuous Positive Airway Pressure (CPAP)
"The CPAP mask may cover only your nose or both your nose and mouth. Another option is to use nasal pillows, which fit in your nostrils. Some other masks fit snugly under your nose."; "The mask must make a seal in order to keep your airway open through the night."; "Your sleep doctor will determine the amount of air pressure needed"; nasal mask: "the most common type of CPAP mask"; full face: "may cover your nose and mouth or may sit under your nose and cover your mouth. This type of mask may help if you have air leaks when using a nasal mask."; nasal pillows: "may help if you have air leaks or don't like the feeling of a mask over your nose and face."; marks or sores "are often due to a poor mask fit"; "Make sure your mask straps aren't too tight. It also may be helpful to buy soft CPAP strap covers"; "If the mask is too big, the straps holding it to your face will need to be pulled tightly"; "A mask that is too small will not seal properly and air will leak out through the edges. The air may blow into your eyes."; "try using a special bed pillow that is shaped for a CPAP mask and tubing"; "Begin using your CPAP for short periods of time during the day while you watch TV or read."; "Clean your mask, tubing and headgear once a week."; "Sometimes a mask style change is necessary to prevent dry nose, mouth or sore throat." Read on 2026-10-10.
[4]
ResMed (manufacturer): Patient Information Guide: Mask Troubleshooting
"sizing across different masks is not always the same. Talk to your clinician to have your face size checked against the sizing tool/fitting template."; leaks at the bridge of the nose, eyes or lip: "Gently pull the cushion away from the face to reinflate it."; "Leak in eyes: Top straps"; "Leak on lip: Bottom straps"; "Cushion membrane is creased or folded"; "Headgear straps are too tight: Adjust straps evenly."; nasal pillows: "Re-seat the pillows by positioning them just inside the entrance of the nostrils ... Do not overtighten." Read on 2026-10-10.
[5]
Fisher & Paykel Healthcare (manufacturer): Troubleshooting guide for CPAP users
"mouth breathers can experience aerophagia when they use nasal masks. If this is happening to you, consider changing your mask style or wearing a chin strap."; "Waking up with dry, irritated eyes is a sign of excessive mask leak."; "Test how it feels while lying in the position you normally sleep in."; claustrophobia: "You may be better suited to a nasal, nasal cradle or nasal pillows mask. These have less facial coverage"; "we are unable to provide you with medical advice".; aerophagia "causes gas, stomach aches, bloating and belching" and the advice is to "Check your CPAP pressure with your healthcare professional"; "An ill-fitting mask can cause unacceptable levels of air leakage and that too can have a drying effect."; skin problems from "a buildup of sweat, oil, and dead skin cells accumulating on your mask and tubing" Read on 2026-10-10.
[6]
Fisher & Paykel Healthcare (manufacturer): Why am I waking up with CPAP mask marks on my face?
"If you are concerned about pressure marks, you may wish to consider using masks that have a smaller footprint on your face, such as a nasal mask and nasal pillows mask."; "Try not to overtighten your mask as this can cause leaks and marks on the face."; "A common cause of mask irritations and rashes is a buildup of bacteria created by dirt and oil from your skin." Read on 2026-10-10.
[7]
Fisher & Paykel Healthcare (manufacturer): What is the best nasal CPAP mask?
"Nasal CPAP masks cover the nose or sit under the nose and are held in place with headgear straps."; "You may prefer a nasal CPAP mask if you: are an active sleeper; feel claustrophobic wearing a full-face mask; ... have a beard or goatee (but not a moustache); breathe through your nose when you sleep; prefer to sleep on your side." Read on 2026-10-10.
[8]
National Heart, Lung, and Blood Institute (NHLBI), NIH: Sleep Apnea: Treatment
"A PAP machine is the most common treatment for sleep apnea."; "Talk to your provider about which type is most appropriate for you."; "Your provider may also recommend that you sleep on your side — not on your back"; side effects "may include congestion, dry eyes or mouth, nosebleeds, or a runny nose. If you experience stomach discomfort or bloating, you should stop using your PAP machine and contact your healthcare provider." Read on 2026-10-10.
[9]
National Heart, Lung, and Blood Institute (NHLBI), NIH: Living With Sleep Apnea
Talk to your provider if "You feel claustrophobic or are bothered by the noise" or "Your mask does not stay on or fit well, or it leaks air"; "Your provider may ask you to try different masks or nasal pillows"; "Clean your mask and wash your face before you put on the mask."; "Be sure to refill prescriptions on time for all of the device's parts that need to be replaced regularly, including the tubes, masks, and air filters." Read on 2026-10-10.

Last checked October 10, 2026. General information from official sources, not medical advice. Sleep apnea is diagnosed and treated by a doctor; do not change your pressure or settings yourself, and talk to your sleep doctor or equipment supplier before changing masks. CPAP masks are prescription devices; we sell nothing.