Circadian-Friendly Light Emitters: From CCT-Tuning to Blue-Free Technology

Common levels of blue radiation are sufficient to disrupt the circadian cycle, calling for blue-depleted emitters in the evening. Most current solutions employ low-CCT and suffer from poor light quality. Aurelien David, chief scientist at Soraa explains the melanopic lumen and its possible sources of inaccuracy related to the uncertainty in assessing the circadian action spectrum. In addition, he also discusses the concept of a blue-free emitter with minimal melanopic lumen at very low CCT and how such a spectrum providing a good light quality can be optimized.

The last two decades of research have revealed a significant effect of blue radiation on our circadian cycle, calling for suitable light emitters. The basics of these physiological effects of blue light are first reviewed. Metrics to measure these effects are introduced, and variations in the estimated circadian action spectrum are illustrated. Strategies to influence circadian entrainment are discussed, including CCT-tuning and more advanced spectral engineering. Finally, the specific challenge of offering low-entrainment light emitters is highlighted; a solution based on the novel blue-free technology is presented, and shown to break the trade-off between light quality and circadian entrainment plaguing conventional LED sources, with applications in general lighting and displays.

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