Taking Your CPAP Mask Off in Your Sleep?

Taking the mask off without remembering it has no single known cause. The authors of a 2021 trial in Medicina call a blocked nose, which they describe as increased nasal resistance, the well-known reason, and say pressure, leak and mask discomfort may also play a part, though supporting evidence is lacking. The most useful thing you can do is find what your nights have in common in the minutes before the mask came off, and take that pattern to your provider.

If you are in your first weeks of therapy, start with our CPAP adjustment period guide, which covers the early weeks and the habits that help. This guide is for when it keeps happening, whether you are a month in or a year in, and you want to know what to look at.

What the research says

Only a few studies look at mask removal during sleep directly, and they are small. Here is what two of them found.

A trial of patients who took the mask off for no known reason. Chen and colleagues, writing in Medicina in 2021, note that some people with sleep apnea "may remove the mask themselves while sleeping, which leads to poor compliance and an insufficient CPAP therapy effect." They write that "the well-known reason that patients unconsciously remove the mask is increased nasal resistance," and that other reasons "may reflect inappropriate pressure settings, flow leakage," or discomfort from the mask, but that supporting evidence is lacking. They also write that "high pressure may lead to patient discomfort, and unconscious removal of the mask when awakening from sleep."

They tested that idea on a Fisher & Paykel auto-CPAP with SensAwake, a feature that lowers the pressure when the machine senses you waking. Of 35 people randomized, 25 finished. Pressures ran slightly lower with the feature on (the abstract reports the average and 90th-percentile pressures as significantly lower; in the paper's own table of medians, only the 90th percentile reaches significance), but over two weeks CPAP use, sleep quality, daytime sleepiness and nasal obstruction scores were similar with it on or off. In that short trial, lowering the pressure did not change how much people used CPAP.

A study of the minutes before the mask came off. Yamaguchi and colleagues, writing in Respiratory Care in 2015, recorded 36 people who used CPAP poorly and 25 who used it well for two nights while letting them remove the device. Twelve of the poor users took it off. Body position changes, and drops in blood oxygen, were both more frequent in the 15 minutes before the mask came off than at other times with the mask on, and 66.7% of the removals were followed within 5 minutes by a change from lying on the back to another position. The good users changed position often too without taking the mask off, which the authors read as a sign that people can adapt to the discomfort of CPAP when they turn over.

Neither study tells you why you take your own mask off. What they do suggest is where to look. A stuffy nose, leak or mask discomfort, turning over in your sleep, and moments when something brings you close to waking are all worth checking.

Things worth checking

A blocked or stuffy nose

This is the reason the 2021 trial's authors call well known. If your nose is often blocked at night, or the mask feels like it is pushing air into a closed nose, that is worth raising with your doctor rather than treating on your own. Our guide to dry mouth and nose on CPAP covers the humidity side of a dry, stuffed-up nose.

Leak and mask discomfort

The 2021 trial's authors list leak and mask discomfort as possible reasons. The 2015 study's finding about position changes fits a mask that shifts or leaks as you turn over, though that is our reading, not the study's conclusion. Work through the fit checks in why your CPAP mask leaks and how to fix it, and if you have been tightening the straps to stop a leak, read what to do when your mask is too tight first.

Pressure

If the air feels too strong when you half wake, say so to your provider. Pressure is their decision, and they can tell you which comfort settings you can change yourself. The 2021 trial is a reminder that a lower pressure is not a guaranteed fix. Please do not change your pressure yourself. Our guide to CPAP pressure settings explains what the settings mean and what to ask.

Trouble falling or staying asleep

Some people have insomnia as well as sleep apnea. In a 2019 trial in Sleep, Sweetman and colleagues gave 145 people with moderate or severe sleep apnea (an AHI of 15 or more) and insomnia either cognitive behavioral therapy for insomnia (CBT-i) before starting CPAP or the usual care. Over the six months, the CBT-i group averaged 61 minutes more CPAP use a night. If you lie awake for long stretches, or wake in the night and cannot get back to sleep, ask your provider whether CBT-i is worth trying. Our Insomnia Severity Index guide can help you put the problem into words before the visit.

Feeling closed in

In a 2005 study in the Western Journal of Nursing Research, Chasens and colleagues found poor CPAP use (under 2 hours a night) was more than two times higher in people who scored 25 or more on a claustrophobia scale. If the mask makes you feel trapped, the daytime practice in the adjustment period guide is a place to start, and your provider or equipment supplier can talk through mask styles that cover less of the face.

Swallowed air

In a 2013 study in the Journal of Clinical Sleep Medicine, Shepherd and colleagues found that 130 of 259 CPAP users (50.2%) reported symptoms of aerophagia, swallowing air during therapy. That study did not look at mask removal, so we cannot tell you it causes it. But if you wake bloated or with a full stomach on the nights the mask comes off, that is worth noting. Our aerophagia guide covers what to do and when to call your provider.

Waking for another reason

CPAP Clarity's own mask-off note names bathroom breaks and comfort adjustments. Anything that wakes you briefly, such as needing the bathroom, a noise or a hot room, is worth writing down, because the machine's record cannot tell those apart. The morning note below helps with that.

What your data can show

The record shows when therapy stopped. It does not say why, or whether you were asleep or awake when the mask came off. Treat the data as a timeline to bring to your provider, not as an answer.

How your machine treats a removed mask

It depends on the machine and how it is set. ResMed's AirSense 10 user guide says that when SmartStart is enabled, "therapy starts automatically when you breathe into your mask. When you remove your mask, it stops automatically after a few seconds." The AirSense 11 splits this into two settings; its user guide says that when SmartStop is enabled, "therapy stops automatically after a few seconds when you remove your mask." On both machines these are features your care provider enables. Other machines have their own settings, so check your own user guide.

In practice, on an AirSense 10 with SmartStart on, or an AirSense 11 with both SmartStop and SmartStart on, taking the mask off in your sleep tends to end a session, and putting it back on starts a new one. That is our reading of the user guides, not a statement ResMed makes about your data. If the setting is off, the user guides' steps have you press the button to stop therapy.

Where it shows on CPAP Clarity

After you import your SD card, here is where to look.

• The sentence about your hours. At the top of the night, the night's mask times read like "Mask on at 10:48 PM, off at 6:02 AM, with one break in between." A break is a gap between two of the machine's sessions in the same night. The sentence gives mask times only when the machine's sessions add up to its hours of use, so on some machines and nights it leaves them out.
• "Your night, hour by hour." Breaks between sessions are drawn as shaded gaps on the night's ribbon. Tap or click a minute inside one and the readout says "mask off" and "The mask was off at this minute." On a BMC machine, and on older Luna G3 cards that CPAP Clarity reads the same way, a minute where the machine recorded no breathing or a leak over 40 L/min reads "At this minute the machine recorded no breathing or a leak over 40 L/min, which usually means the mask was off, so its readings are left out."
• "What your data means." If, inside one session, the recorded pressure drops to almost nothing for at least two minutes, the list can carry a "Mask removed mid-session" item. If that happened more than 1.5 times a night on average over the past week (on at least three recorded nights), it can also carry "Mask off often this week". A summary-only machine records no pressure through the night, so neither item can appear there.
• "For your doctor." When "Mask off often this week" is on the night, the questions under "Questions for your appointment" can include "I keep taking the mask off during the night. Can we look at comfort or fit?" The printed therapy report has its own "Questions for your appointment" list too.

Look at the minutes before each break

This follows the Yamaguchi study's lead of looking at what happened just before the mask came off. On each night with a break, open "Every chart and number" at the bottom of the night, then "Detailed charts". Every row sits on the same clock, so you can look at the 15 minutes or so before each gap.

1. Leak Rate. A climb in leak that starts several minutes before the gap fits a mask that shifted or broke its seal. A spike right at the edge of the gap is usually the mask coming off, not what caused it.
2. The events row. A run of events right before the gap is worth showing your provider. Events scored as you wake up are not always what they look like; our guide to CPAP events while awake explains why, and why you should not discount them on timing alone.
3. Therapy Pressure. On an auto machine, note whether the pressure had been rising before the gap.
4. SpO2. If you wear a supported oximeter, its oxygen row shows whether your oxygen dipped in those minutes.

Then write a line in the morning. Note the time you noticed the mask was off if you did, anything you remember (a blocked nose, a dry mouth, the mask digging in, a bloated stomach, needing the bathroom, nothing at all), and which side you woke up on. A week of nights with both the chart and the note is much easier for a provider to work with than "I keep taking it off."

When to talk to your provider

ResMed's own answer to a reader who often removes the mask while sleeping without realising it is that "there may be various contributing factors requiring a personalised approach," and to discuss it with a ResMed Sleep Coach, your ResMed dealer or your doctor. Bring it up with your sleep physician or equipment supplier if any of these fit.

• You keep finding the mask off on most nights after your first few weeks.
• Your night view shows "Mask off often this week".
• Your nose is blocked most nights.
• You wake bloated, or the air feels too strong when you half wake.
• You lie awake for long stretches, or cannot get back to sleep after waking.
• The mask makes you feel trapped.

Take the nights with breaks, your morning notes and your therapy report. Our guide to sharing your CPAP data with your doctor covers what to bring, and improving CPAP compliance has habits that help alongside whatever your provider suggests.

Import your SD card and see when the mask came off →

Common Questions

Why do I take my CPAP mask off in my sleep without remembering?

There is no single known cause. The authors of a 2021 trial call a blocked nose (increased nasal resistance) the well-known reason, and say pressure, leak and mask discomfort may play a part, though evidence for those is lacking. A 2015 study found position changes and oxygen drops were more frequent in the 15 minutes before people took the mask off.

Can my CPAP data show when the mask came off?

It can show when therapy stopped, not why. On CPAP Clarity, a gap between two sessions in one night shows as a break in the hours sentence and a shaded gap on the night's ribbon, and a stretch of at least two minutes with the pressure near zero inside a session can show as "Mask removed mid-session". The data cannot tell whether you were asleep or awake.

Does my CPAP stop when I take the mask off?

It depends on the machine and its settings. ResMed's user guides say that with SmartStart enabled on the AirSense 10, or SmartStop on the AirSense 11, therapy stops automatically after a few seconds when you remove your mask. Your care provider enables those features. Check your own machine's user guide for how it behaves.

Will a lower pressure stop me from taking the mask off?

Not necessarily. In a 2021 trial of a feature that lowers the pressure when it senses you waking, pressures were lower with it on, but over two weeks CPAP use was similar with it on or off among the 25 people who finished. Pressure is your provider's decision, so raise it with them rather than changing it yourself.

When should I talk to my provider about taking the mask off?

When it keeps happening on most nights after your first few weeks, when your night view shows "Mask off often this week", or when a blocked nose, bloating, trouble staying asleep or a trapped feeling is part of the picture. Bring a week of nights with breaks and a short note from each morning.

Primary Sources

• Chen YL, Chuang LP, Lin SW, et al. Effects of Pressure Control Device (SensAwake) on Obstructive Sleep Apnea (OSA) Patients Who Remove the Mask for Unknown Reasons during Automatic Continuous Positive Airway Pressure (Auto-CPAP) Therapy: A Prospective Randomized Crossover Trial. Medicina (Kaunas). 2021;57(9):915. Nasal resistance as the well-known reason for unconscious removal, pressure, leak and mask discomfort as possible reasons with supporting evidence lacking, and the two-week crossover result. PMC full text (opens in new tab)
• Yamaguchi Y, Hibi S, Ishii M, et al. Removal of the CPAP Therapy Device During Sleep and Its Association With Body Position Changes and Oxygen Desaturations. Respir Care. 2015 May;60(5):658-665. PubMed 25587170 (opens in new tab)
• Sweetman A, Lack L, Catcheside PG, et al. Cognitive and behavioral therapy for insomnia increases the use of continuous positive airway pressure therapy in obstructive sleep apnea participants with comorbid insomnia: a randomized clinical trial. Sleep. 2019;42(12):zsz178. PubMed 31403168 (opens in new tab)
• Chasens ER, Pack AI, Maislin G, Dinges DF, Weaver TE. Claustrophobia and adherence to CPAP treatment. West J Nurs Res. 2005;27(3):307-321. PubMed 15781905 (opens in new tab)
• Shepherd K, Hillman D, Eastwood P. Symptoms of aerophagia are common in patients on continuous positive airway pressure therapy and are related to the presence of nighttime gastroesophageal reflux. J Clin Sleep Med. 2013;9(1):13-17. PubMed 23319899 (opens in new tab)
• ResMed. AirSense 10 user guide. SmartStart starts therapy when you breathe into the mask and stops it a few seconds after you remove it, when enabled by your care provider. ResMed AirSense 10 user guide (PDF) (opens in new tab)
• ResMed. AirSense 11 user guide. SmartStart and SmartStop, features enabled by your care provider. ResMed AirSense 11 user guide (PDF) (opens in new tab)
• ResMed. How can I keep my mask on at night? I often remove it while I'm sleeping without realising it. (patient FAQ). ResMed FAQ (opens in new tab)