Fast forward to the present. In an unforeseen chain of events, all of the programmers at my company all sit on one side of a newly erected wall, and QA/Services/Helpdesk sits on the other side. We have decided as a team to leave the lights off on our side of the wall, and it has made a tremendous improvement. Lighting related headaches and nausea are practically nonexistent.

I’ve noticed lately that the number one search term that brings people to this site is "flicker vertigo", sometimes combined with "aspartame". It seems time to revisit this problem.

Flicker vertigo, annoyingly, is a topic that doesn’t seem to have a lot of information behind it yet. Sure, there are lots of hits on search engines, but if you look at the content excerpts, most of the pages seem to be copied from one another. Almost all of the results involve aviation. The most unique results I was able to find are the following:

• http://www.iflyamerica.org/flicker-vertigo.asp – Anecdotal information from flying a single engine propeller airplane.
• http://www.narcap.org/PerceptualDisorders.htm – Article from the National Aviation Reporting Center on Anomalous Phenomena (NARCAP) including a couple of paragraphs about flicker vertigo. Again, mostly anecdotal evidence from single engine propeller airplanes and helicopters.
• http://asrs.arc.nasa.gov/callback_issues/cb_268.htm – More anecdotal evidence from a Boeing 767 captain affected by the strobe on top of a fuel truck.
• http://en.wikipedia.org/wiki/Flicker_vertigo – The Wikipedia entry. Just a stub for now, since it appears to have been created 10 November 2006. I find it strange that it took so long for flicker vertigo to make it onto Wikipedia.

None of the above links contain much of any information about flicker vertigo. The prevailing opinion seems to be that it only happens to those involved in the aviation industry. One commonality in the sources is that they consider a flicker between 4 and 20 Hz to be the cause of "standard" flicker vertigo. (Of course, most of the article reference the NARCAP info at some point, so that may be why they all use the same numbers.)

One cause of flicker vertigo that I didn’t find mentioned was one that gets me every time – driving on a tree lined road at a time of day where the shadows are falling on the road. The sun "flickers" in and out of the trees with a frequency that’s probably very close to 20 Hz. I can only tolerate this for a minute or two. Any longer than that and I get a splitting headache, dizziness and nausea. I’m sure there’s some term for this that would turn up more hits in a search engine, but to me it’s clearly flicker vertigo.

I mentioned that some of the searches that hit my site include the word "aspartame". In my original post, I stated that evidence had been found that aspartame was linked to an increase in flicker vertigo among (you guessed it) pilots. I still have not been able to find the study (or studies) that this information came from. There is an article on the Flight Safety Foundation’s website, but you have to be a member to access it. I didn’t feel it was worth US$280 for me to become a member just to read the article.

One of the biggest frustrations in trying to find anything associated with aspartame is the sheer number of sites on the Web that are devoted to misinformation and FUD. I mean, how am I going to take anything seriously on a website that declares aspartame to be the "Thalidomide of the ’90s"?

It’s entirely possible that aspartame has some kind of effect on flicker vertigo. My own experience doesn’t seem to bear it out. When I wrote the original article, I was drinking one drink a day that contained aspartame and experiencing vertigo. Currently, I have three to four drinks a day with aspartame, with no vertigo effects. It’s possible that the single drink I eliminated was not what stopped the vertigo. The more likely explanation is that I made some other change that was the real solution – less sugar, less alcohol, etc.

I’m not saying that aspartame is innocent. It’s a man made substitute for a natural substance, so the body is going to process it differently. Does this mean it might cause health issues? I’m not going to say it won’t, but I can’t say that it will, either. I didn’t pay enough attention in organic chemistry…

I will go out on a limb and say that for the majority of the population aspartame has nothing to do with flicker vertigo. If you are already predisposed to flicker vertigo, maybe aspartame can aggravate it, but it certainly doesn’t cause it.

technorati tags:flicker, vertigo, flicker vertigo, aspartame, dizzy, health

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The number one aggravator of my problem is fluorescent lighting – especially in older buildings. According to this page, most older office buildings are using ballasts that operate at 60Hz, meaning the light cycles on and off 120 times a second. This is definitely noticeable. Most office buildings I have worked in are older, so I think it’s safe to assume that many of the fixtures are still using the older ballasts. New ballasts are supposed to operate at around 25,000Hz, eliminating flicker and buzz. I’ll believe it when I see it.

One thing that I found, but have been unable to find credible sources for, is the effect of aspartame on flicker vertigo. Aspartame is used as a sugar substitute in nearly every brand of diet soda. When you’re a person like me who has to watch his sugar intake, diet sodas are pretty much the norm. My drinking habits during the day used to include water or iced tea in the morning, diet soda with lunch, and more water or tea in the afternoon. I began to have problems with extreme vertigo and headaches right after lunch. As soon as I cut out the aspartame, the vertigo subsided to its normal, flickering overhead light caused intensity. So, even though I’ve been unable to find good evidence for the aspartame link, it seems to hold some weight.

Once upon a time, I had my own office. I had the luxury of not turning the overhead lights on every morning, which was immensely helpful. For some reason, however, most people seem to be unable to function with the lights off. From what I understand, nearly every person that uses a computer suffers from some level of CVS. Why do people insist on making it worse for themselves?

I get to my current job early – anywhere from an hour to two hours before everybody else. Needless to say, I never turn on the overhead lights. If I need to see something, my cube has small lights I can turn on that offer indirect lighting. The first person after me to show up in the mornings seems to take the lack of light as a personal affront, and turns them all on. As the lights come on, I can actually feel myself starting to squint and the first glimmerings of a headache start to form.

So far I’ve been laughed at when I suggest leaving the lights off, been told I can’t unscrew the lights that are nearest me, and mocked because I must be some kind of wimp to get headaches from the lights. Hopefully my eye doctor can come up with something that I can use as leverage. I’ve even thought about building a makeshift roof for my cube.