A recent study conducted by Fagerhult's Lighting Academy, found that high levels of LED light can boost students' cortisol levels.
The study measured the hormone levels of students at a University in Sweden. Researchers found that in LED-lit rooms, with luminance levels of 100cd/m2, the hormone level of cortisol increased in the students. Cortisol is a hormone that helps control our body clock. The higher cortisol levels are, the more awake and alert we feel.
This was based on a study from 2009 where fluorescent T5 luminaires showed an increase in cortisol levels in students. This happened when they were exposed to high luminance in the morning and afternoon. Though both lights show an increase in cortisol levels, it was found that LEDs increased cortisol levels slightly faster.
The research facility is now looking at students' grades to see if the improved hormone levels result in better academic performance, but this has not yet been proven in relation to LED-lit classrooms. The 2009 study on increased fluorescent light levels showed an increase in performance by one grade on average in the dark part of the year.
An earlier study conducted in 2007 found that colour temperature did not make a difference whereas light intensity did.
Director of Fagerhult Lighting Academy, Henrik Clausen, said: "People started asking whether LED would have the same effect as T5, so we had to repeat our research. We did that at a school in Sweden where we found the same hormone release results. Actually, the pupils' cortisol levels raised a little bit faster with LEDs than they did with fluorescents. It's probably because there is an inherent peak of blue light in LEDs but we don't know that for sure."
Clausen added that the results should not be applied to everything without proper research: "If you want to do research you have to choose a path and we chose to focus on classroom lighting, so we don't claim that this approach works for everything."