Which type of light source is more likely to produce higher EML?

• A. Warmer amber lights (2700 K)
• B. Dim light under 1000 lux
• C. Red-yellow sodium lamps
• D. Daylight-like lights (5000-6500 K)

Answer: (D)

EML (equivalent melanopic lux) reflects how strongly light stimulates the melanopsin-containing cells in the eye that regulate circadian responses and alertness. Those cells respond best to blue light around 460–480 nm, so light sources with more blue content will produce a higher melanopic response for the same overall illuminance. Daylight-like lighting, with a high correlated color temperature (about 5000–6500 K), has a spectrum richer in blue wavelengths than warm amber (2700 K) or sodium lamps, increasing melanopic stimulation and thus EML. Even if a warm light is bright, its limited blue content means a lower EML than blue-rich daylight-like light. Dim lighting under 1000 lux provides less total light, further reducing EML. So daylight-like, blue-rich lighting at adequate brightness yields the highest EML.