# Circadian Energy — Body Clock & Energy Tracker > Personalized daily energy curve and sleep window calculator using HealthKit data. (iPhone/iPad app by Markus Sekulla.) - Source: https://appshunter.io/ios/app/circadian-energy/id6759719638 (this page in markdown: same URL + `.md`) - Developer: [Markus Sekulla](https://appshunter.io/developer/1880340583) - Category: Health & Fitness, Productivity - Price: Free with in-app purchases - Rating: 5.00/5 from 3 App Store ratings · 1 written reviews indexed - Age rating: 4+ - Requires: iOS 26.0 · 3 MB - Languages: English, French, German, Italian, Spanish - Released: 2026-03-10 - Data updated: 2026-08-22 - Monetization: free with in-app purchases - User reviews in markdown: https://appshunter.io/ios/app/circadian-energy/id6759719638/reviews.md ## What is Circadian Energy? Circadian calculates your personal energy curve for the day. Based on your sleep, heart rate variability, and workouts, the app shows you when you're fit today and when your next peak is coming. 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. Not a generic daily rhythm, your individual energy. 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 your optimal bedtime and wake-up time based on your energy curve and your personal sleep needs. 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. ## Key features - Personalized energy curve calculation - Optimal sleep window recommendations - HealthKit data integration - Chronotype detection - Home screen and lock screen widgets - Apple Watch complications ## Pricing and in-app purchases Base price: Free. **One-time purchases** | Purchase | Price | Type | | --- | --- | --- | | Unlock Circadian Energy | $4.99 | one-time | ## Recent user reviews (1 of 1) All indexed reviews: https://appshunter.io/ios/app/circadian-energy/id6759719638/reviews.md ### 5/5 — YAYY *2026-04-04* I love how simple this is, it just gives me an energy score. It’s a really clean interface and the watch complications are really nice. It’s also cheap! I didn’t have to pay a subscription for this, just $5 which is maybe even less than I’d be willing to pay for it. Free trial for 7 days too and you don’t have to give payment info beforehand so you don’t get caught paying a subscription when you didn’t intend to **Developer response:** Thanks for the kind words! I built Circadian Energy as something I wanted to use myself, so keeping it simple with fair pricing was a no-brainer. Glad that resonates. And nice to hear the watch complications are getting some love too. Hope it keeps helping you stay on top of your energy! ## Frequently asked questions about Circadian Energy ### What is Circadian Energy? Circadian Energy calculates your personal energy curve for the day based on your sleep, heart rate variability, and workouts. It helps you understand when you're most fit and when your next peak energy is expected. ### How does Circadian Energy personalize my energy curve? It uses your real HealthKit data, including sleep amount and quality, heart rate variability, workout impact, sleep debt, chronotype, daylight exposure, and wrist temperature to create a unique energy profile. ### Does Circadian Energy have ads? No, Circadian Energy does not contain advertisements. The app is free to try for 7 days and then requires a one-time purchase to unlock all features. ### Can I see my energy level on my watch? Yes, Circadian Energy offers four Apple Watch complications (Circular, Rectangular, Corner, and Inline) to display your current energy level at a glance directly on your watch face. ### Is my health data safe with Circadian Energy? Yes, all health data stays on your device. The app emphasizes privacy with no account creation, no cloud storage, and no tracking of your personal information. ### What devices does Circadian Energy support? Circadian Energy is supported on iPhone and Apple Watch. Widgets are also available for your home screen and lock screen. ### How often is Circadian Energy updated? The latest version, 1.1.0, was released on May 27, 2026, indicating active development. Users can expect regular updates to improve functionality and add new features. ### What is the cost of Circadian Energy? Circadian Energy offers a 7-day free trial with all features. After the trial, a one-time purchase is required to unlock the app permanently, with no subscriptions or hidden costs. ## Version history (last 5 releases) ### 1.1.0 — 2026-05-27 - New Trends view: compare today's energy curve against any past day or date range. - Optional notifications in the morning and evening. - Insight right under the curve on the Dashboard: explains what is shaping your curve the most today. - Smaller bug fixes that could occasionally make the curve sit too high. Enjoy the update. ### 1.0.9 — 2026-04-13 New watch face complications for Apple Watch: - Corner: Energy level with progress bar - Inline: Energy level with current phase This brings the total to 4 watch complications. Enjoy the update. ### 1.0.8 — 2026-04-10 Fixed a bug where the trial period sometimes did not start reliably. ### 1.0.7 — 2026-04-08 New Lock Screen Widgets * New: Your current energy level right on your Lock Screen, as a circular gauge or compact text. * Fix: Improved display of the nightstand view in landscape. Enjoy the update! ### 1.0.6 — 2026-04-07 Sleep Window Widget and StandBy * New sleep window widget shows your bedtime and wake windows in the evening, and the next peak and dip during the day. * New: Rotate your iPhone to landscape for a nightstand view with clock and energy curve. * New: Scrolling along the curve now shows your sleep recommendation in the energy area. * Fix: Scrolling along the curve is now more reliable. Enjoy the update! ## More apps by Markus Sekulla - [Keptiq](https://appshunter.io/ios/app/keptiq/id6759723841) All apps by Markus Sekulla: https://appshunter.io/developer/1880340583 --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-22.*