Melanopic light
Melanopic light is a way of scoring light by how strongly it reaches the eye pathway that tells the body clock whether it is day or night.
What does Melanopic light mean?
The word melanopic names a weighting, not a kind of lamp or a brand of bulb. Every light measurement scores the spectrum against some response curve. Ordinary lux is weighted to the eye's daytime brightness response, while melanopic weighting scores the same light by how strongly it drives the receptor pathway that reports day and night to the body clock. The two curves peak at different wavelengths, so two sources can carry very different melanopic signals at the same measured brightness. That is why words like bright, dim, warm, or cool describe what a room looks like without describing what the clock received. The standardised quantity built on this weighting is melanopic equivalent daylight illuminance, or mEDI, defined by the CIE in 2018. Melanopic light is the concept, and mEDI is the number that measures it.
Sources cited for Melanopic light
Every number on this Melanopic light page traces to one of the 2 sources below: 1 peer-reviewed.
Institutional & standards
- CIE S 026:2018, System for Metrology of Optical Radiation for ipRGC-Influenced Responses to Light (defines mEDI)
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