# Opsin: Circadian Sun & Sleep — Sunlight timing, better sleep > Syncs daily activities with the sun for improved circadian rhythm and sleep. (iPhone/iPad app by Opsin App LLC.) - Source: https://appshunter.io/ios/app/opsin-circadian-sun-and-sleep/id6788143818 (this page in markdown: same URL + `.md`) - Developer: [Opsin App LLC](https://appshunter.io/developer/6788143820) - Category: Health & Fitness, Lifestyle - Price: Free with in-app purchases - Rating: 5.00/5 from 3 App Store ratings · 2 written reviews indexed - Age rating: 4+ - Requires: iOS 18.0 · 2 MB - Languages: American English - Released: 2026-08-04 - Data updated: 2026-08-16 - Monetization: freemium - User reviews in markdown: https://appshunter.io/ios/app/opsin-circadian-sun-and-sleep/id6788143818/reviews.md ## What is Opsin? Opsin syncs your day with the sun. Most health apps hand you more numbers. Opsin does the opposite — it tells you the one thing to do for your circadian rhythm right now, then shows you it worked in your own sleep and recovery. Light sets your body clock. Opsin sets your light. WHAT OPSIN DOES - Live sun times and your daily light windows — morning light, vitamin D window, blue hour, and bedtime, calculated for your exact location and updated automatically all year. - A real, dynamic dawn alarm — recalculates to civil dawn every night, so you wake into the light without ever resetting a thing. - See what morning light does to you — Opsin reads your sleep and HRV from Apple Health and reflects the difference light makes in your own body. - Jet-lag plans with exact clock times — shift your body clock before you fly, so you land already adjusted. - Your lights, automatically on sun time — optional HomeKit support. WHY IT MATTERS A regulated circadian rhythm is the foundation under sleep, energy, and mood. Instead of highlighting downstream problems, Opsin addresses the behavior at the root — and makes it effortless. PRIVATE BY DESIGN No account. No backend. Your health and location data are processed entirely on your device and never leave your phone. SUBSCRIPTION Opsin Premium unlocks every feature. $9.99/month or $79/year, each with a 7-day free trial. Payment is charged to your Apple ID; subscriptions renew automatically unless canceled at least 24 hours before the period ends. Manage or cancel anytime in your App Store settings. Opsin is a general wellness and educational tool. It is not a medical device and does not diagnose, treat, or prevent any condition. Consult a qualified professional for medical concerns. Scripture quotations taken from the New American Standard Bible® (NASB), Copyright © 1960, 1971, 1977, 1995 by The Lockman Foundation. Used by permission. www.Lockman.org Terms of Use: https://opsinapp.com/terms Privacy Policy: https://opsinapp.com/privacy ## Key features - Live sun times and light windows - Dynamic dawn alarm - Sleep and HRV tracking integration - Jet-lag adjustment plans - HomeKit support ## Pricing and in-app purchases Base price: Free. **Subscriptions** | Subscription | Price | Period | | --- | --- | --- | | Opsin Premium (Monthly) | $9.99 | per month | | Opsin Premium (Annual) | $79.99 | per year | ## Recent user reviews (2 of 2) All indexed reviews: https://appshunter.io/ios/app/opsin-circadian-sun-and-sleep/id6788143818/reviews.md ### 5/5 — Essential for my Health *2026-08-11* Opsin has been incredible for my health. I’ve noticed a huge difference in my energy and the way I feel. No more afternoon slump. I feel more motivated. I procrastinate less. I love all of the extra features and I especially love the daily Bible verses!! So glad I found this app! ### 5/5 — Excellent for tracking sun *2026-08-05* Opsin makes sunrise, light exposure, and sleep guidance easy to understand. The app feels pretty intuitive, and the dawn alarm and jet-lag tools seem especially useful. ## Frequently asked questions about Opsin ### What is Opsin's core function? Opsin's core function is to help users regulate their circadian rhythm by providing personalized sunlight timing information and guidance. It focuses on optimizing light exposure throughout the day to improve sleep, energy, and mood. ### How does Opsin use my data? Opsin is designed with privacy in mind. Your health and location data are processed entirely on your device and never leave your phone, as the app has no account or backend. ### What are the subscription options for Opsin Premium? Opsin Premium offers two subscription plans: $9.99 per month or $79 per year. Both plans include a 7-day free trial and can be managed or canceled anytime through your App Store settings. ### Does Opsin have ads? No, Opsin does not contain advertisements. The app is free to download and use, with an optional premium subscription for advanced features. ### How does Opsin's dawn alarm work? Opsin features a dynamic dawn alarm that recalculates to civil dawn each night. This ensures you wake up naturally with the light without needing to manually reset the alarm daily. ### Can Opsin help with jet lag? Yes, Opsin provides specific jet-lag plans with exact clock times to help you shift your body clock before flying. This aims to ensure you land already adjusted to your new time zone. ### What devices is Opsin available on? Opsin is available on iPhone and iPad devices. It integrates with Apple Health to read sleep and HRV data. ### Is Opsin a medical device? No, Opsin is a general wellness and educational tool. It is not a medical device and does not diagnose, treat, or prevent any medical condition. Consult a qualified professional for any health concerns. ## Version history (last 2 releases) ### 1.1 — 2026-08-11 Opsin now runs on iPhones with iOS 18 and later — welcome to everyone who couldn't join us at launch. • A new introduction that shows you what Opsin does and why your body clock matters • Jet-lag plans rebuilt on the Eastman/Burgess light protocol — realistic shift rates, a progress ring that tracks how far you've re-timed, and an optional plan for the trip home • Guidance for setting up an evening red screen filter • Daily verses refined throughout True Alarm still requires iOS 26. ### 1.0 — 2026-08-04 No release notes. --- *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 2026-08-16.*