Apple Watch
Per-night sleep stages, heart rate, HRV, and overnight SpO2 from your Apple Health export. Read locally, never sent anywhere.
Read your Apple Health export, joined to your CPAP nights
An Apple Watch records sleep stages, heart rate, heart-rate variability (HRV), respiratory rate, and (on Series 6 and later) overnight blood-oxygen estimates. The Apple Health app shows you these numbers; CPAP Clarity is what you import them into when you want them sitting next to your CPAP therapy data on the same calendar night.
The import path is the export.zip your iPhone's Health app generates on demand. Open Health, tap your profile, tap Export All Health Data, AirDrop the ZIP to your Mac (or email it to yourself). Drop the ZIP onto the dashboard import zone. CPAP Clarity unzips it in your browser, streams the embedded export.xml through a Web Worker so your UI stays responsive, and stores per-night summaries in your browser's IndexedDB. We cannot write to your Apple Health account and the ZIP is not retained anywhere outside your browser tab.
Once imported, the dashboard automatically joins each Apple Watch night to the CPAP session on the same date. A night with high CPAP leak that also shows reduced REM percentage and elevated resting heart rate tells a richer story than either source alone. The full join logic is documented in the Apple Watch guide for CPAP users.
How to read these numbers
Sleep stages (Deep, Core, REM, Awake) are estimated from movement and pulse pattern, not measured by EEG. They track relative night-to-night change reliably; they do not substitute for sleep-lab scoring. HRV (SDNN) is recorded opportunistically throughout the day; the per-night average is drawn from samples that fell inside the sleep window. Heart rate averages exclude third-party HealthKit writers (AutoSleep, Pillow, Bevel) so the number reflects the Apple Watch only. SpO2 on Series 6 and later is a wrist-based estimate, not a calibrated medical measurement; treat it as one of several data points, not as a diagnostic threshold.
These are wellness measurements, not clinical signals. Wearable sleep stages are estimates derived from movement and pulse, not the gold-standard EEG a sleep lab uses. Use these readings as one more data point in conversation with your sleep physician, not as a replacement for the CPAP data your machine records.
Frequently asked questions
How do I export my Apple Health data?
On your iPhone, open the Health app, tap your profile picture in the top right, then scroll down and tap Export All Health Data. iOS produces an export.zip you can AirDrop or email to your computer. The ZIP contains an export.xml file (the only file CPAP Clarity reads) plus workout GPX files and an HL7 CDA mirror we discard. A multi-year export commonly lands at 200 to 400 MB; CPAP Clarity unzips it in your browser and parses it via a Web Worker so the UI stays responsive.
Which Apple Watch models are supported?
Every Apple Watch model that runs watchOS 8 or later writes sleep records, heart rate, and HRV into Apple Health, so every modern Apple Watch (Series 3 through 10, SE, Ultra) is supported today. Sleep stage breakdown (Deep / Core / REM) requires watchOS 9 or later (Series 4 and newer). Overnight SpO2 requires Series 6 or later hardware. CPAP Clarity surfaces what your model recorded; Series 3 / 4 / 5 nights render sleep stages and HR without the SpO2 card.
Will Apple Watch sleep stages match a sleep study?
Not exactly. The Apple Watch estimates sleep stages from movement and heart-rate pattern, while a clinical sleep study scores stages from EEG. The two methods agree on broad structure (sleep / wake, REM presence) but disagree on minute-by-minute scoring. Use these stages as a relative trend, not as an absolute clinical label. A drop in REM percentage across multiple nights with elevated CPAP leak is meaningful even if the absolute REM minutes do not match a sleep lab. CPAP Clarity surfaces these as wellness metrics, not clinical signals.
How does Apple Watch SpO2 compare to a pulse oximeter?
Apple Watch SpO2 (Series 6 and later) is a wrist-based estimate sampled opportunistically during sleep, not a continuous medical-grade measurement. It tracks broad overnight trend reliably; it does not substitute for a dedicated fingertip or wrist pulse oximeter (Wellue O2 Ring, OxySmart, O2Ring S). For users who want continuous overnight SpO2 alongside their CPAP nights, CPAP Clarity also reads the Wellue family. Both streams can be imported and viewed side by side on the dashboard.
Can I import multiple years of Apple Watch data at once?
Yes. The Apple Health export is your full account history. The reference fixture (a multi-watch household with three different Apple Watch generations over time) parses in about 4.5 seconds on a 2024 MacBook Pro through the byte-streaming Web Worker. Multi-watch nights are merged via interval-union so a Series-4-to-Series-9 upgrade week does not double-count sleep stages. Third-party HealthKit writers (AutoSleep, Pillow, Bevel) are filtered out of the HR and HRV aggregates so the per-night numbers reflect the Apple Watch only.