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Apple Watch · Apple Health export

See your Apple Watch data next to your CPAP

CPAP Clarity reads your Apple Health export and shows sleep stages, heart rate, HRV, and blood oxygen alongside your CPAP nights. Browser-only import. Nothing leaves your device.

View the Apple Watch dashboard

Can the Apple Watch detect sleep apnea?

Partly, and Apple is unusually careful about the wording. Apple Watch Series 9 and later, Ultra 2, and SE 3 carry a sleep apnea notifications feature, cleared by the FDA via 510(k) in September 2024. It tracks a metric called Breathing Disturbances from the accelerometer and reviews it every 30 days, after at least 10 nights of sleep wear.

The limits matter as much as the feature. Apple states it looks for consistent signs of moderate to severe sleep apnea, that it is not intended to diagnose, treat, or aid in the management of sleep apnea, and that not all people with sleep apnea receive a notification. Mild apnea is outside its detection range, so a quiet watch is not an all-clear.

If you suspect sleep apnea, the right next step is a validated screening questionnaire and a clinical evaluation. Both are linked below.

What CPAP Clarity reads from your Apple Watch

Sleep Stages
Awake / REM / Core / Deep

Apple Watch estimates stages from wrist movement and heart signals on watchOS 9 and later (Series 4 onward). CPAP Clarity totals each stage for the night and renders a proportional stage bar next to your CPAP session. Nights recorded before stages existed import as plain sleep time.

Heart Rate During Sleep
Avg / Min / Max BPM

Watch heart-rate readings inside the sleep window, summarized for the night. Readings written into Apple Health by third-party sleep apps are filtered out, so the numbers reflect the watch sensor.

Resting Heart Rate
Apple's daily value

Apple computes one resting heart rate per day. A multi-night drift above your personal average can flag stress, illness, or sleep debt before you feel it.

Heart Rate Variability
SDNN average (ms)

Apple Watch takes HRV readings opportunistically rather than continuously. CPAP Clarity averages the readings that fall in your sleep window and shows the sample count, so you know how much signal sits behind the number.

Blood Oxygen
Avg / Min (Series 6+)

Series 6 and later and all Ultra models sample blood oxygen during sleep when sleep tracking is on. The samples are spot checks, not a continuous trace. CPAP Clarity shows the overnight average and minimum with the sample count behind them.

Recovery Callouts
RHR + HRV vs baseline

When your resting heart rate runs above your personal baseline while HRV runs below it, the dashboard flags the combination. Low overnight blood oxygen with enough samples behind it gets its own callout.

Multi-Year History
Full export archive

The Apple Health export contains every night the watch has logged. CPAP Clarity streams the archive in your browser, even when the file inside runs to gigabytes, without uploading anything.

CPAP Context Join
Same-date side by side

Every Apple Watch night is joined by calendar date to your CPAP session. The dashboard shows AHI, leak, and usage hours next to sleep stages, HRV, and blood oxygen for the same date.

How the Apple Watch compares to other ways to track sleep

FeatureApple WatchOura RingHome Sleep Study
Sleep stage estimateYes: Movement + heart rateYes: Movement + heart rate + HRVYes: Clinical EEG, AASM scored
Heart rate variabilityYes: Sampled readings, nightly averageYes: Overnight average, nightlyPartial: Not the primary metric
Blood oxygen (SpO2)Partial: Series 6 and later, sampledPartial: Gen 3 and Gen 4 onlyYes: Continuous, medical-grade
Body temperaturePartial: Series 8 and later, wrist tempYes: Baseline deviationNo: Not standard
Daily wear comfortPartial: Wrist, largerYes: Ring, lightweightNo: One night only, in lab or at home
FDA cleared to diagnose apneaNo: Notification feature onlyNo: NoYes: Standard of care

The pattern across consumer trackers holds for the watch too: good agreement with the lab on whether you were asleep, weaker agreement on which stage you were in at any given minute. Use it for trends across weeks, not verdicts about single nights.

Which should you use?

Choose Apple Watch if

you already wear one daily. You want Apple's sleep apnea notification feature (Series 9 and later, Ultra 2, SE 3). You value fitness, daytime heart rate, and sleep in a single device.

Choose Oura if

you want to track sleep architecture, HRV, and recovery trends with minimal hardware on your body overnight, and a battery that does not need nightly charging around your sleep schedule.

Choose a sleep study if

you suspect untreated sleep apnea and need a diagnosis. Your symptoms are not explained by your current therapy. Your physician needs medical-grade evidence for a treatment decision.

What a typical night might look like

Representative example. Numbers below are illustrative, not a real user's data.

In a representative night, the CPAP side might show AHI 1.2 across 6 hours and 48 minutes of use, median leak around 3 L/min, and pressure running 7.4 to 10.6 cmH₂O. The Apple Watch side of the same night might report 13 percent deep sleep, 20 percent REM, 55 percent core, 12 percent awake, an average sleeping heart rate of 57, resting heart rate of 54, HRV averaging 38 milliseconds across 9 samples, and blood oxygen averaging 96 percent with a sampled minimum of 92.

What the two together tell you in this example: the CPAP is preventing scored events, AHI well under 5. Stage percentages are in ordinary ranges. The sampled SpO2 minimum of 92 is a spot check, not a continuous-oximetry nadir, so by itself it says little; the normal average matters more.

None of those numbers prove anything on their own. Together they make for a more concrete conversation with your sleep physician than "AHI 1.2, looks fine." A multi-week drift, like resting heart rate climbing while HRV sinks, is the kind of pattern worth asking about. A single night by itself is not.

How to import your Apple Watch data

1

Export from the Health app

On your iPhone, open the Health app, tap Summary, then your picture or initials at the top right, then Export All Health Data. Apple saves everything as a compressed archive; long histories can take a minute to package.

2

Save the archive somewhere you can reach

AirDrop it to your computer, save it to Files, or share it to yourself. The archive is a ZIP with your health records inside; you do not need to unzip it.

3

Drop the ZIP onto CPAP Clarity

Open the Apple Watch page at /apple-watch and drop the ZIP onto the import card. The whole parse runs in your browser. Nothing leaves your device.

Go to the Apple Watch import page

Frequently Asked Questions

Can the Apple Watch detect sleep apnea?

Within limits, yes. Apple Watch Series 9 and later, Ultra 2, and SE 3 include an FDA-cleared sleep apnea notifications feature (cleared via 510(k) in September 2024). The watch tracks a metric called Breathing Disturbances using its accelerometer and reviews it every 30 days; you need to wear the watch to sleep at least 10 nights in that period. Apple's own framing is precise: the feature looks for consistent signs of moderate to severe sleep apnea, it is not intended to diagnose or treat anything, mild sleep apnea is outside its range, and not all people with sleep apnea receive a notification. CPAP Clarity does not read the breathing disturbances metric. If you get an Elevated notification, talk to your doctor.

Which Apple Watch models work with CPAP Clarity?

Any Apple Watch whose data lands in Apple Health can import. Sleep stages need watchOS 9 or later, which runs on Series 4 and newer; nights recorded before stages existed import as total sleep time without a stage breakdown. Blood oxygen needs Series 6 or later or any Ultra. The sleep apnea notification feature is a separate thing with its own list: Series 9 or later, Ultra 2, or SE 3.

How accurate are Apple Watch sleep stages?

Apple Watch estimates stages from wrist movement and heart signals; a sleep study scores them from brain activity using clinical criteria. Apple has published its estimation methodology, and consumer trackers in general agree well with the lab on sleep versus wake but less well on minute-by-minute staging. Treat the stages as a consistent trend instrument: same wrist, same algorithm, every night. What matters is how your deep and REM percentages move over weeks, not whether one night's number is exact.

What about Blood Oxygen on US watches?

Blood Oxygen works on Series 6 and later and all Ultra models. For watches bought in the United States on or after January 18, 2024 (part numbers ending in LW/A), Apple's documented behavior is that the analysis runs on your iPhone and results appear in the Health app rather than on the watch. Results in the Health app are part of your Health data, which is what the export carries. Two caveats straight from Apple: measurements during sleep only happen if sleep tracking is on, and the readings are designed for general fitness and wellness, not medical use.

Why don't I see respiratory rate or wrist temperature?

CPAP Clarity does not import them yet. The watch records respiratory rate overnight, and Series 8 and later plus Ultra and SE 3 sample wrist temperature during sleep; both show up in the Health app. CPAP Clarity currently reads sleep stages, heart rate, HRV, and blood oxygen from the export. If respiratory rate or wrist temperature next to your CPAP data would help you, say so through the feedback page; it helps us prioritize.

Is my Apple Health data shared with anyone when I import it?

No. The export is parsed entirely in your browser. CPAP Clarity does not upload your Apple Health data to any server. Your sleep stages, heart rate, HRV, and blood oxygen are stored only in your browser's local IndexedDB, on the device you imported from. Clearing your browser data, or using the data hub at /data, removes them.

Do I need a CPAP machine to use Apple Watch with CPAP Clarity?

No. CPAP Clarity reads the Apple Health export on its own. You can import without any CPAP data and view your sleep stages, heart rate, HRV, and blood oxygen at /apple-watch. The dashboard lights up additional cross-night context when both streams are present, but the Apple Watch side of the site works standalone.

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