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 melanopsin-containing retinal ganglion 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 Features
📊 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)
🎯 Actionable lighting recommendations based on time of day
💡 Light source type selection (daylight, LED, incandescent, halogen, fluorescent)
💾 Save measurements with timestamps and comments
🔧 Built-in calibration for optimal accuracy
{{flag}} Multilingual support, including {{language}}
⚙️ 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. This app tells you whether your current light is suitable for the time of day.

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.

Based on Science
The melanopic calculations are based on the CIE S 026 standard and established spectral models. The app brings circadian light assessment to your smartphone, making it accessible to everyone.

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.

Support & Feedback
Your feedback helps improve the app. Contact us at [email protected] for support or suggestions.

Turn your phone into a circadian light meter today and take control of your light environment.