Almost always, no. It is the first thing people assume the machine must do, and it is the one thing it is deliberately built not to do. Here is what actually happens instead, the single setting that comes closest, and how to check your own machine in about two minutes.
A standard CPAP is not a warning device. When the mask comes off in the night, a typical machine does two things, neither of which involves waking you:
So the information exists. It simply arrives after the night it describes.
ResMed machines — the AirSense and AirCurve families — have a setting called Leak Alert. With it enabled, the device beeps when the mask leaks badly, and taking the mask off counts as a bad leak. That is the closest thing to a mask-off alarm that comes in the box.
Two caveats, and they matter:
Philips DreamStation 2 machines do not have a dedicated mask-off alert at all. Older Respironics models had a leak alert that would beep when a mask came off; it is not a feature you can count on finding on current hardware. If your machine is another brand, the answer is in its user guide under alerts or alarms — and "no entry" is itself the answer.
This is not an oversight. Three reasons, and once you see them the behaviour stops being surprising:
A CPAP is not life support. Devices that must alarm on a disconnection — ventilators keeping someone breathing — are a different class of equipment, with alarm requirements to match, because the consequence of a missed disconnection there is immediate. A CPAP treats a condition that is serious over years, not over minutes. Masks are even built with anti‑asphyxiation vents so that a person breathes room air if pressure stops. The design goal is "do no harm when it comes off", not "shout".
An alarm on every leak would be unbearable. The machine cannot tell a removed mask from a mask that has slipped, a yawn, a mouth leak, or a turn onto one side. Something that fired on all of those would wake you several times a night, every night, and the machine would be unplugged within a week. Manufacturers who have tried loud alerting on sleep devices have generally pulled back from it for exactly this reason.
The machine does not know what it is looking at. It measures pressure and flow in a tube. It cannot see the bed. It does not know if you are asleep, awake, reading, or in the bathroom — which is also the answer to the question people often ask next: no, a CPAP cannot tell whether you are asleep.
Everyone who searches this question has already worked out that the machine will not help, and lands on one of these:
This is our product, so weigh it accordingly. MaskAlarm turns a spare phone on a stand into exactly the thing the CPAP does not include: it watches the bed and sounds an alarm — usually within a minute or two — when the mask has come off, and keeps sounding until the mask is back on or you stop it. The alarm is in the room, loud, and aimed at a sleeping person, which is the part a nightstand beep is not.
The limits, plainly: it is a consumer convenience aid, not a medical device. It does not diagnose, treat or measure anything, and it is not a substitute for prescribed therapy, your clinician's advice, or fixing a mask that does not fit. It is best-effort — it needs a reasonably clear view of the bed and a phone that stays plugged in — and it costs money, where checking your leak data costs nothing. If the mask comes off because of a solvable fit problem, solve that first; an alarm is for the nights that happen anyway.
Does my CPAP have an alarm? Check the user guide for your exact model under alerts. If it is a ResMed AirSense or AirCurve, a leak alert exists but your provider controls it. If it is a current Philips DreamStation, there is no dedicated mask-off alert.
Why do I wake up with the mask off and no memory of removing it? That is the normal case, not a strange one. Removal during light sleep is usually unremembered, which is why the morning evidence — where the mask ended up, whether the straps were undone — tells you more than your recollection does.
Do the mask-off hours still count towards compliance? They are not meant to, but how each machine records them varies, and a huge leak is not always a clean gap in the usage total. If an insurer or supplier requirement depends on it, ask them to read the leak and usage data with you.
Call your equipment supplier if the mask is old, leaking, or has never fitted properly, and ask directly whether a leak alert can be enabled. Call the sleep clinic if you are waking unrefreshed, if the symptoms that led to therapy have come back, or if the mask is coming off every single night despite the fit being right — that pattern is worth a conversation about pressure settings rather than a conversation about alarms.
MaskAlarm (CPAP Mask-Off Alarm) is a consumer convenience aid and is not a medical device. It does not diagnose, treat, cure, or prevent any disease, and it is not a substitute for medical care or caregiver supervision. Device behaviour described here is based on manufacturers' published user guidance and can change between models, firmware versions and provider settings — check your own machine's user guide. Always follow the guidance of the treating clinician.