Being the lighting nerd that I am, I have a deep-seeded belief that lighting design can make the world a better place. That’s not always about creating beautiful spaces, it’s also about studying the effects of lighting on people and trying to create the best lighting systems for given circumstances. This led me to investigating a problem that has been brought to my attention several times. Parents on Twitter and elsewhere have told me that their kids suffer headaches, distraction and general poor performance under fluorescent lighting. The problem is that there is scant scientific evidence to support that theory and much of it is dated. Also, why do some kids study under fluorescent light with no problem at all? I did a little investigation and here’s what I came up with.
The Flicker Problem
A 1985 study performed in Australia concluded that autistic students performed better under incandescent light than under fluorescent. The study went on to postulate that perhaps the flicker of fluorescent lighting was to blame. Subsequent study has proven that for all people and children especially the invisible flicker of fluorescent lighting is detrimental.
Here’s how the flicker works in basic form. When electricity passes through anything, a light bulb, your computer or a blender it does so at a specific rate measured in Hz. In the US that’s generally 60hz but it varies. That cycle rate is generally observed at double the service rate in lighting applications so here in the US that means that there is a 120Hz flicker rate through our lighting gear. That means that 120 times per second the light will flicker. That’s very fast - too fast in fact to be perceptible by the human eye - more on that later. This flicker happens in all light sources, but is less observable in incandescent lamps because once the filament heats up the pulse of electricity doesn’t cool it enough to change the light output very much. So once the lamp is hot, even though electricity is pulsing the filament stays hot making the flicker much less prominent. In fluorescent sources there is a fleeting loss of light as the power pulses through the gear.
Here’s where the flicker problem gets complicated. Fluorescent fixture manufacturers have responded by creating electronic ballasts that regulate power flow. This this problem can be reduced to near zero - essentially it is made so fast that it cannot be perceived at all. Electronic ballasts can increase the flicker rate to 20,000Hz or 30,000 Hz so fast they cannot be seen by anyone of any sensitivity. The problem is that a 100Hz flicker and a 20,000Hz flicker are both imperceptible to basic human vision. So you cannot tell with the naked eye what lighting you’re looking at.
My Theory on Why This is a Bad for Autistic Kids (and kids in general)
So knowing what we know about the flicker problem in a technical sense and knowing that some autistic kids have reported problems studying and concentrating under fluorescent light but others haven’t what are we to make of this problem? Well for starters there has not been a lot of study of this phenomena, mostly because ethically conducting such research is very difficult to do. What we do know is that kids are more sensitive to the invisible flickering of fluorescent lamps. We also know that this sensitivity varies in individuals of all ages. So to my mind fluorescent flicker could very well be detrimental to autistic (and other) kids.
There are two reasons this is inconsistently reported. The first is that some classrooms and institutions have installed newer more high-end control gear. These electronic ballasts will eliminate the flicker problem and make it much easier on all students. Other schools/institutions have older or cheaper control gear will allow the flicker to continue and since you can’t see it, the staff of these institutions are likely to argue it isn’t there. The second is that the sensitivity to this problem is likely quite varied for kids on both on the autism spectrum and not, if there was a uniform response to any stimulus it would be much easier to diagnose and get rid of.
Lastly, there are other competing problems in classroom lighting like glare and general over-lighting of the space these could also contribute to headaches and poor performance.
So What Should a Parent Do?
All I can recommend at this point is broaching the subject with school officials. Because the problem is invisible to the naked eye it would likely be difficult to get schools to change their lighting schemes. If the institution isn’t willing to take action they should at least be willing to share information. They should be willing to tell you the make and model of the ballasts of the fluorescent fixtures. That will tell you how old they are and if they are magnetic (bad) or electronic (good). If you can’t make out what ballast it is ask and electrician or email me. At least then you can know if there is a flicker problem or if there is something else possibly going on.
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