Study Design: Examining Light Through the Lens of Cognitive Performance
The experiment involved 12 healthy adults and compared three types of lighting (DL, CLED, and DLED) at three illuminance levels (300, 500, and 1000 lx). Researchers evaluated cognitive performance (using the 2-back working memory test), physiological fatigue and alertness (using CFF and HRV methods), as well as participants’ subjective perception of the environment.
DLED vs. LED vs. Daylight: Differences in Cognitive Performance
The results showed that the optimal conditions were provided by an illuminance level of approximately 500 lx. At this level, reaction speed in the working memory test improved by 6.2% compared with both the 300 lx and 1000 lx conditions, while participants exhibited the lowest fatigue levels (CFF) and the highest alertness and comfort. Although the higher illuminance level of 1000 lx stimulated working memory slightly better than 300 lx, it did not lead to the best overall results. Instead, it produced the highest level of physiological fatigue.
The spectral composition of light proved to be just as important as illuminance itself. In this respect, full-spectrum DLED lighting achieved results comparable to daylight and significantly outperformed conventional LED lighting. High-quality daylight LED lighting could therefore functionally replace natural daylight in indoor environments.
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