# Circadian Rhythm Light Meter — Melanopic mEDI mDER EML M/P MI > Measures melanopic light content to regulate circadian rhythm and improve sleep/alertness. (iPhone/iPad app by Contechity AB.) - Source: https://appshunter.io/ios/app/circadian-rhythm-light-meter/id6761270886 (this page in markdown: same URL + `.md`) - Developer: [Contechity AB](https://appshunter.io/developer/1649290454) - Category: Utilities, Education - Price: Free with in-app purchases - Rating: 4.00/5 from 2 App Store ratings - Age rating: 17+ - Requires: iOS 15.0 · 44 MB - Languages: American English, Afrikaans, Bulgarian, Catalan, Croatian, Czech, Danish, Dutch, Estonian, Filipino and 30 more - Released: 2026-04-12 - Data updated: 2026-09-04 - Monetization: free with in-app purchases - User reviews in markdown: https://appshunter.io/ios/app/circadian-rhythm-light-meter/id6761270886/reviews.md ## What is Circadian Rhythm Light Meter? Support your circadian rhythm by measuring the melanopic content of your light environment! Designed for health-conscious individuals, lighting designers, workplace wellness consultants, and anyone interested in how light affects sleep, alertness, and well-being. WHAT IS MELANOPIC LIGHT? Your body's internal clock — the circadian rhythm — is to a large extent regulated by specialized cells in your eyes (ipRGCs) that are sensitive to blue light around 490 nm. Traditional lux meters only measure total brightness, but not all light affects your circadian system equally. This app measures the melanopic component — the light that actually drives your body's response. KEY METRICS • Melanopic Equivalent Daylight Illuminance (mEDI) — the primary CIE S 026 circadian metric • Melanopic Daylight Efficacy Ratio (mDER) — compare circadian effectiveness of light sources • Melanopic/Photopic Ratio (M/P) — balance between visual and circadian stimulation • Melanopic Irradiance (MI) in W/m² per CIE standard • Equivalent Melanopic Lux (EML) — for WELL Building Standard compatibility • Color Temperature (CCT) and Illuminance (lux) KEY FEATURES • Actionable lighting recommendations based on time of day, mEDI and color temperature • Light source type selection (daylight, LED, incandescent, halogen, fluorescent) • Save measurements with timestamps and comments • Built-in calibration for optimal accuracy • Multilingual support, including english • Customizable settings IDEAL FOR • Improving sleep quality — identify excessive evening blue light • Boosting daytime alertness — ensure sufficient melanopic light exposure • Human Centric Lighting (HCL) design and verification • WELL Building Standard compliance using EML measurements • Evaluating light therapy lamps and SAD devices • Testing blue light blocking glasses effectiveness • Research and education in circadian photobiology THE RIGHT LIGHT AT THE RIGHT TIME Bright, blue-rich light during the day promotes alertness and synchronizes your circadian rhythm. In the evening, reducing melanopic light allows melatonin to rise naturally, preparing your body for restful sleep. ACCURACY For optimal accuracy, use a common white paper when measuring. Hold it at eye level, illuminated by the light source you want to assess. Select the correct light source type for the most reliable melanopic estimates. While pre-calibrated for good results, optional calibration further enhances accuracy on your specific device. Privacy Policy, https://contechity.com/circadian-light-meter/pp.html End User License Agreement, https://contechity.com/circadian-light-meter/eula.html FREE FOR A LIMITED TIME Enjoy full functionality for a few weeks. After that, choose a one-time fee or subscription — still at a fraction of the cost of a dedicated device. DEDICATED SUPPORT Your feedback helps improve the app. Contact us at apps@contechity.com for support or suggestions. Turn your phone into a circadian light meter today and take control of your light environment. ## Key features - Measure melanopic equivalent daylight illuminance (mEDI) - Analyze melanopic daylight efficacy ratio (mDER) - Calculate melanopic/photopic ratio (M/P) - Get actionable lighting recommendations - Select light source types for accurate readings - Save measurements with timestamps and comments ## Pricing and in-app purchases Base price: Free. **Subscriptions** | Subscription | Price | Period | | --- | --- | --- | | Full Access (Month) | $0.99 | per month | **One-time purchases** | Purchase | Price | Type | | --- | --- | --- | | Full Access (Lifetime) | $9.99 | one-time | ## Frequently asked questions about Circadian Rhythm Light Meter ### What is the Circadian Rhythm Light Meter app? Circadian Rhythm Light Meter is a utility app that measures the melanopic content of your light environment. It helps you understand how light affects your body's internal clock, influencing sleep and alertness. ### How accurate is the Circadian Rhythm Light Meter? For optimal accuracy, the app recommends using a common white paper at eye level, illuminated by the light source you want to assess. Selecting the correct light source type and using optional calibration further enhances reliability. ### What are the key metrics provided by Circadian Rhythm Light Meter? The app provides key metrics such as Melanopic Equivalent Daylight Illuminance (mEDI), Melanopic Daylight Efficacy Ratio (mDER), Melanopic/Photopic Ratio (M/P), Melanopic Irradiance (MI), Equivalent Melanopic Lux (EML), Color Temperature (CCT), and Illuminance (lux). ### What are the subscription options for Circadian Rhythm Light Meter? Circadian Rhythm Light Meter offers a free trial period of 14 days for full functionality. After the trial, users can choose a one-time fee or a subscription plan, with the monthly subscription costing $0.99. ### Does Circadian Rhythm Light Meter have ads? The provided data does not specify if the app contains advertisements. However, it does mention a free trial followed by a one-time fee or subscription, suggesting monetization beyond ads. ### What devices is Circadian Rhythm Light Meter compatible with? The app is available for mobile devices, as indicated by its listing as a mobile application. Specific operating system compatibility (iOS or Android) is not detailed in the provided information. ### How often is Circadian Rhythm Light Meter updated? The app was last updated on June 14, 2026, with version 1.1.0. This indicates a recent update, suggesting ongoing development and support for the application. ### What is the age rating for Circadian Rhythm Light Meter? Circadian Rhythm Light Meter has an age rating of 17+. This is likely due to the technical nature of the information presented and its target audience. ## Version history (last 3 releases) ### 1.1.1 — 2026-09-03 • Improved camera reliability. • More reliable language downloads on shaky networks. • Misc minor improvements. This is a new app. Please let us know what you think in a review! ### 1.1.0 — 2026-06-14 • Misc minor improvements This is a new app. Please let us know what you think in a review! ### 1.0.0 — 2026-04-12 No release notes. ## More apps by Contechity AB - [Flicker Meter for Light - PWM](https://appshunter.io/ios/app/flicker-meter-for-light-pwm/id1672848632) - [White Balance Kelvin Meter](https://appshunter.io/ios/app/white-balance-kelvin-meter/id6443791592) - [Colorimeter Camera Color Meter](https://appshunter.io/ios/app/colorimeter-camera-color-meter/id6449255688) - [Light Spectrometer Wavelength](https://appshunter.io/ios/app/light-spectrometer-wavelength/id6450930820) - [Lux Light Meter Photography](https://appshunter.io/ios/app/lux-light-meter-photography/id6478221966) - [Screen Brightness Nits Meter](https://appshunter.io/ios/app/screen-brightness-nits-meter/id6749894754) All apps by Contechity AB: https://appshunter.io/developer/1649290454 ## Related topics [circadian rhythm light meter](https://appshunter.io/ios/topics/circadian-rhythm-light-meter) · [contechity ab](https://appshunter.io/ios/topics/contechity-ab) --- *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 2026-09-04.*