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 relia