Circadian: Sleep & Energy
Markus Sekulla Health & Fitness iPhoneiPadiPod touchApple Watch
Circadian: Sleep & Energy is a free Health & Fitness app for iPhone and iPad by Markus Sekulla. Rated 5.0/5 from 4 ratings. Requires iOS 26.0.
- Rating
- 5.0
- 4 ratings
- Price
- Free
- on the App Store
- Size
- 4 MB
- Age 4+
- Updated
- Sep 19
- 2026 · v1.1.1
Screenshots
About Circadian: Sleep & Energy
Plan your day around your sleep rhythm. Circadian estimates your daily energy pattern from sleep, heart rate variability and activity to help you find times for activity and rest. YOUR ENERGY CURVE The curve is based on the two-process model of sleep research (Borbély, 1982) and is personalized with your real HealthKit data. The curve is a model-based estimate. What feeds in: - Sleep amount and sleep quality from last night - Heart rate variability (HRV) and resting heart rate - Workout impact on your energy level - Sleep debt from the last 14 days - Chronotype detection (early bird, normal, night owl) - Daylight exposure and wrist temperature SLEEP WINDOW Circadian recommends a bedtime and wake-up time based on your energy curve and your personal sleep needs. SMART ALARM Choose a personal wake window. Circadian selects a wake time within it based on your calculated energy curve. You can also set up optional waking on your Apple Watch. WIDGETS See your current energy level right on your home screen or lock screen. Also available on Apple Watch. APPLE WATCH Your energy level at a glance, right on your wrist. 4 complications for your watch face: Circular, Rectangular, Corner, and Inline. PRIVACY All health data stays on your device. No account, no cloud, no tracking. ONE-TIME PURCHASE Try free for 7 days with all features. Then unlock once. No subscription, no hidden costs.
What’s new
Version 1.1.1 · Updated September 19, 2026
Sleep data updates more reliably after a later sync. Improvements to the energy curve, history and notifications, plus a corrected Health permission flow during setup. The smart alarm supports a personal wake window and optional waking on Apple Watch.
App privacy
The developer, Markus Sekulla, reported these privacy practices to Apple.
Data Not Collected
The developer does not collect any data from this app.
Alternatives to Circadian: Sleep & Energy
Looking for apps like Circadian: Sleep & Energy? Here are 6 similar apps on the App Store. The highest rated is My Circadian (5.0/5), and all 6 are free to download.
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SunSync - Circadian Tracker
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Circadian AI Sleep & Rhythm
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Circadian Rhythm: Body Clock
4.6
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Circadian Rhythm & Sleep: ARC
4.4
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BodyClock - Circadian Rhythm
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My Circadian
5.0
| App | Rating | Price | Last updated | Compare |
|---|---|---|---|---|
| Circadian: Sleep & Energy | 5.0 / 5 (4 ratings) | Free | September 19, 2026 | |
| SunSync - Circadian Tracker | – | Free | Jun 24, 2026 | Compare |
| Circadian AI Sleep & Rhythm | – | Free | Aug 30, 2026 | Compare |
| Circadian Rhythm: Body Clock | 4.6 / 5 (11) | Free | Sep 28, 2026 | Compare |
| Circadian Rhythm & Sleep: ARC | 4.4 / 5 (8) | Free | Oct 3, 2026 | Compare |
| BodyClock - Circadian Rhythm | – | Free | Jun 21, 2026 | Compare |
| My Circadian | 5.0 / 5 (2) | Free | Jan 6, 2024 | Compare |