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Circadian requires iOS 26 or later. The optional Apple Watch app requires watchOS 26 or later. You do not need an Apple Watch to use the iPhone app.

Try every feature free for seven days. A permanent unlock costs €6.99 once in the German App Store. No subscription or recurring fees. In other countries, the app displays your local price before purchase.

Circadian estimates your energy pattern using a model based on sleep research. Your sleep and other available Health data personalize the curve. It does not measure your actual performance or replace a medical assessment.

Choose your chronotype in Settings or use “Derive from sleep data” to apply a suggestion based on your sleep patterns.

No. Circadian can use sleep data from any source that writes to Apple Health. Without suitable data, the app uses default values. The optional wrist alarm requires an Apple Watch.

Open Settings → Alarm, enable the smart alarm and allow the system permission request. Choose a wake window or a fixed time. You can also use the sleep window on the dashboard to set an alarm. The calculated wake time is a model estimate, not live sleep-stage detection. Set up your alarm in Circadian, not Apple’s Clock app.

Enable waking on Apple Watch in Circadian and allow automatic launch in the Watch app. Wear your Watch with Sleep mode active. During the wake window, the Watch uses movement cues and wakes you with haptics. An iPhone alarm is also scheduled for your latest wake time. Movement cues are not a measurement of sleep stages.

Add Circadian from the widget gallery on your Home Screen or Lock Screen. Open the app first so it can provide current curve data. A small sleep-window widget is available for StandBy; on Apple Watch, add a Circadian complication.

Circadian includes sleep data that is added or corrected later. First check that the data has reached Apple Health, then reopen Circadian. Historical trend curves are also recalculated using the latest available data, so they can change.

Notifications are off by default. In Settings, you can enable a daily insight about the factors affecting your curve and a reminder for your sleep window. The app asks for permission separately. Set up your alarm independently.

No. Circadian works entirely without an account, login, or registration. All calculations happen locally on your device.

Circadian reads health data from Apple Health: sleep times, heart rate variability (HRV), resting heart rate, respiratory rate, workouts, daylight exposure, and wrist temperature. All data is processed exclusively on your iPhone.

Without HealthKit access, Circadian shows a default curve based on population data. You can grant access at any time in iOS Settings under Health.

Open Circadian, go to Settings, and tap "Restore Purchase". Your purchase status will be automatically restored via your Apple account.

Yes. Circadian includes a dedicated Watch app and widgets for watch face complications. The energy curve is transferred from your iPhone; no raw health data is sent to the Watch.

Circadian does not store any data on servers. Uninstalling the app deletes all locally stored data. You can revoke HealthKit access under Settings → Health → Data Access & Devices → Circadian.