Physics According to a new study, red light is more dazzling than expected
Red light is more dazzling than previously assumed. This is the conclusion reached by researchers at the Swiss Federal Institute of Technology in Lausanne (EPFL) in a new study.
14.10.2025, 11:45
SDA
For the study, published on Tuesday in the journal "Scientific Reports", the researchers carried out experiments in an office in which sunlight shone through different colored glazing. The 56 study participants unanimously reported that red glazing caused the most disturbing glare, followed by blue and, to a lesser extent, green filters.
"The glare caused by red glazing was a real surprise, as it contradicts the previous literature," said researcher Jan Wienold, who was involved in the study, in a press release on the EPFL study. According to the researcher, it was previously assumed that only blue light was more dazzling than white light of the same intensity. This assumption was primarily based on studies of car headlights. However, the new study shows that red light exhibits similar behavior.
Models unreliable
These results call into question the "spectral sensitivity function V(λ)" developed a hundred years ago and still used today, which describes how the human eye perceives light of different wavelengths. According to Wienold, the existing models for assessing glare in strongly colored light are only reliable to a limited extent.
This finding could also have practical consequences: In future, buildings could be fitted with more intelligent glazing that provides better protection against glare. The new findings could also be taken into account when planning LED lighting systems for colored light. Wienold and his team have already started further experiments to investigate the effects of other colors and additional methods and to improve the current models for glare assessment.
