A CPAP machine that stops recording data almost always has a fixable cause, and the most common culprit is the SD card. Whether the card is missing, improperly seated, full, or corrupted, the result looks the same: your companion app or clinician portal shows blank nights, zero hours, or no sessions at all. Less often, the problem sits with a wireless connection, a software glitch, or a machine setting you may not know exists. The stakes go beyond curiosity, because missing data can jeopardize insurance coverage during the compliance window that matters most.
The SD Card Is the First Thing to Check
Nearly every modern CPAP records usage, leak rates, and respiratory events to a small SD card tucked into a slot on the side or back of the machine. If that card is not present, not seated correctly, or has gone bad, the machine will still deliver air pressure normally but will have nowhere to store the data. You can use the device all night and feel great, and your app or your sleep clinic will see nothing.
Start by powering the machine off, removing the card, and reinserting it firmly until it clicks. A card that looks like it is in place can be a fraction of a millimeter shy of making contact. If the machine came with a card already installed and you have never touched it, it is still worth pulling it out and reseating it, especially after the machine has been moved, cleaned, or bumped off a nightstand.
SD cards also wear out. They are rated for a limited number of write cycles, and a CPAP writes small amounts of data every single night. After a few years of nightly use, the card can develop bad sectors and silently stop accepting new data. Replacing it with a fresh card of the same type often solves the problem immediately. Most machines use a standard SD or micro-SD card, and the manual will specify the maximum capacity the device supports. A card that is too large for the machine’s firmware to handle can appear blank even though it is physically fine.
A Full Card Looks the Same as a Missing One
CPAP machines store weeks or months of detailed data, depending on the card’s capacity and how much information the machine logs per session. Once the card fills up, the behavior varies by manufacturer. Some machines overwrite the oldest data automatically and keep recording. Others simply stop writing new sessions when the card is full, which means your most recent nights vanish from your app while older data remains. If you have been using the same card for years without ever clearing it, a full card is a real possibility.
You can check this by inserting the card into a computer with a card reader. The file structure will show dated folders or data files, and you can see how much free space remains. If the card is nearly full, copying the data to your computer and then formatting the card through the CPAP machine’s menu (rather than through your computer, which can use the wrong file system) will give you a fresh start. Some manufacturers recommend formatting the card in the machine specifically because the device creates a particular folder structure it expects to find on startup.
Wireless Connectivity Problems
Many newer CPAP machines transmit data wirelessly to a cloud platform, which then feeds your companion app or your provider’s compliance dashboard. If the machine has both an SD card and a wireless modem, data can be present on the card but missing from your app, which makes it look like nothing was recorded when in fact the recording happened just fine and the transmission failed.
Wireless data transfer relies on either a built-in cellular modem or a Bluetooth or Wi-Fi connection to your phone. Cellular modems depend on network coverage in your bedroom, and if your machine sits in a basement or a room with poor signal, it may not upload nightly sessions. Bluetooth connections require the app to be running (or at least backgrounded) on your phone and the phone to be within range of the machine during or shortly after your sleep session. Wi-Fi models need a stable home network and correct credentials stored in the machine’s settings.
A simple test: check the SD card directly. If the card has data but your app does not, the issue is connectivity, not recording. Restarting the machine, moving it closer to a window or router, or manually syncing through the app’s settings often clears the backlog. Some machines queue up unsent sessions and transmit them in bulk once the connection is restored, so a few days of missing data in the app can suddenly appear all at once.
App and Software Glitches
The companion apps that display your CPAP data are not always as reliable as the machines themselves. App updates can introduce bugs that prevent data from displaying, even when the machine recorded everything correctly. A corrupted app cache, a failed login token, or a mismatch between the app version and the machine’s firmware can all create the appearance of missing data.
If your app suddenly shows no recent sessions, try logging out and back in. On smartphones, force-closing the app and reopening it clears minor glitches. Clearing the app’s cache (available in your phone’s app settings) can resolve display issues without losing your account data, since the actual records live on the cloud server, not on your phone. If you recently updated your phone’s operating system, check whether the app developer has released a compatibility update.
Desktop software like OSCAR, a popular open-source tool that reads CPAP data directly from the SD card, can serve as a second opinion. If OSCAR shows complete data on the card but your manufacturer’s app shows gaps, the problem is definitively on the app or cloud side, not with the machine.
Machine Settings That Disable or Limit Recording
Some CPAP machines have a setting that controls how much detail gets recorded, and in rare cases, a setting that disables data logging entirely. This is uncommon on consumer-facing devices, but it exists on certain clinical models or machines that have been configured by a provider before being handed to the patient. If your machine was set up by a sleep lab or a durable medical equipment supplier, the data-recording preferences may have been adjusted during setup.
Accessing the clinical menu varies by brand. On some machines, holding a combination of buttons during startup enters a provider-level settings screen where recording options live. If you are not comfortable navigating these menus, your equipment provider can check the setting during a routine visit or remotely if the machine supports telehealth management. The key point is that the machine might be working perfectly in every other respect while quietly not storing session data because a toggle was turned off.
Power Interruptions and Short Sessions
CPAP machines typically begin recording a session when they detect that you are breathing through the mask and stop recording when the mask is removed or airflow ceases. A session that lasts only a few minutes, such as when you put the mask on and then take it off to get water, may not register as a full session in the app. Some machines set a minimum session length before the data is saved and displayed. If you see occasional missing nights interspersed with normal ones, think about whether those nights involved interrupted sleep, mask removal, or power disruptions.
Power outages mid-session can also cause data loss. If the machine loses power abruptly rather than being shut down through normal mask removal, the session file may not close properly, resulting in a corrupted or missing entry. Using a battery backup or surge protector helps prevent this, especially in areas with unstable power.
Why Missing Data Matters for Insurance
This is where missing CPAP data stops being an annoyance and becomes a financial problem. In the United States, Medicare and many private insurers require documented proof that you are using your CPAP before they will continue covering the device. The Centers for Medicare and Medicaid Services defines adherence as using the device for at least four hours per night on 70% of nights during a consecutive 30-day period within the first 90 days of therapy.1PubMed Central. Centers for Medicare and Medicaid Services Positive Airway Pressure Adherence Criteria May Limit Treatment to Many Medicare Beneficiaries If your machine is not recording data during that initial window, you may appear non-compliant even if you have been using the device every single night.
Failing to meet the adherence threshold can mean the supplier takes the machine back, and you have to restart the qualification process. If you discover missing data early in your compliance period, contact your equipment provider immediately. They can often pull data directly from the machine, check the SD card, or note in your file that the gap was due to a technical issue rather than non-use. The sooner you flag the problem, the more options you and your provider have.
Brand-Specific Quirks Worth Knowing
Different CPAP manufacturers handle data storage and transmission in slightly different ways, and being aware of your machine’s particular habits can save you from unnecessary troubleshooting.
ResMed’s AirSense series, one of the most widely used lines, records data to both an SD card and a built-in cellular modem that transmits to the myAir app and the AirView provider portal. If your myAir app shows no data but the AirView portal (which your provider accesses) does, the issue is likely with your app or phone, not the machine. ResMed machines also have a known behavior where the SD card must be formatted in FAT32; a card formatted in a different file system will not be recognized.
Philips Respironics DreamStation models use a micro-SD card and offer both cellular and Bluetooth connectivity. The DreamMapper app has had periods of instability following software updates, and Philips’s recall of certain DreamStation models in 2021 complicated the data landscape further, as some replacement devices came with different connectivity features than the originals.
Fisher & Paykel’s SleepStyle machines use a smaller user base and a different app ecosystem. Their data export process involves connecting the machine directly to a computer via USB in some models, rather than relying on an SD card. If you are looking for a card slot and cannot find one, check whether your particular model uses a different transfer method entirely.
When Data Exists but Looks Wrong
Sometimes the complaint is not that data is completely absent but that it looks implausible. A session shows zero hours when you know you slept all night, or the leak rate reads as impossibly high, or the AHI (the count of breathing disruptions per hour) is wildly different from what your sleep study showed. These anomalies usually point to mask fit issues rather than recording failures. A mask that is not sealed properly can cause the machine to misread airflow, generating data that technically recorded but does not reflect what actually happened.
A zero-hour session that you know lasted all night can also result from a time or date error on the machine. If the internal clock resets (after a power outage, battery replacement, or factory reset), the machine may record the session under a wrong date, making it invisible when you look at tonight’s data but findable if you scroll to a different calendar date. Checking and correcting the machine’s clock is a quick fix that is easy to overlook.
How to Confirm Your Machine Is Recording Right Now
If you want to verify that your CPAP is actively logging data before going to sleep tonight, here is a practical sequence:
- Check the SD card: Remove it, inspect it for visible damage, reinsert it firmly, and power on the machine. Most machines display a card icon on the screen when the card is recognized.
- Run a short test session: Put on your mask and breathe normally for five to ten minutes, then remove the mask and check the machine’s on-screen summary. If the machine shows a session with usage time, it recorded data.
- Sync your app: Open your companion app and force a sync. If the test session appears, the full pipeline from machine to card to cloud to app is working.
- Read the card on a computer: If the app still shows nothing, insert the card into a computer. Navigate to the data folders and look for a file with today’s date. If the file exists, the machine recorded data and the problem is in transmission or display, not recording.
Running this check before your compliance deadline gives you time to fix whatever is broken, whether that means replacing a card, updating the app, or calling your equipment provider for help.
Older Machines and End-of-Life Firmware
CPAP machines are generally prescribed for a five-year replacement cycle, but many people use theirs for longer. Older machines may stop receiving firmware updates, and their companion apps or cloud services can be discontinued. When a manufacturer sunsets a cloud platform, the machine may still record data locally to the SD card, but the app that once displayed that data no longer works or no longer connects. This does not mean the data is gone. It means you need a different way to access it.
OSCAR and similar third-party tools can read SD card data from most major CPAP brands regardless of whether the manufacturer’s own software is still supported. If your machine is older and your app has stopped updating, switching to a direct card-reading workflow is often the most reliable path. Your sleep clinic can also read the card during appointments using their own clinical software, which tends to support older device models longer than consumer apps do.
If your machine is approaching the end of its useful life and you are noticing more frequent data gaps, erratic readings, or hardware glitches like a flickering display or unusual motor noise, the recording problem may be a symptom of broader wear. At that point, discussing a replacement with your provider makes more sense than continuing to troubleshoot a device that is aging out across multiple systems.