OH GOD MY EYES

November 30, 2007 7:44 PM

Why do blue Christmas lights hurt the hell out of my eyes?

Recently there has been an upswing in the number of people with these bright blue Christmas lights strung all over their yards. Normally I love Christmas lights -- they're so festive! -- but these blue ones make me physically repulsed somehow. They hurt my eyes and give me a headache like someone has put a knife into my skull. It's a similar (but toned-down) version of what happens if I look at a blacklight/ultraviolet light, which give me ridiculously bad pain, even to the point of making me throw up.

What gives? These blue lights suck so much that I am freaked out to even drive right now: when I see them, I instinctively turn my head, and I keep worrying that one of these times I'll do it and run into a car/deer/whathaveyou.

Is there a reason for this phenomenon? Is anyone else experiencing this? Am I just insane?

posted by InnocentBystander to health & fitness (11 comments total)

Could it be related to what is talked about in this previous askme question?
posted by Memo at 7:56 PM on November 30, 2007

LED style Xmas lights are almost always have unfiltered rectification. This results in a horrible 60Hz flicker that is noticeable to some people (me for example). I find the blue ones the worst offender for the brain piercing feel when directly observed. Mostly I think because they appear to be both brighter and more point sourcy though I don't know if this an equipment difference or a physiology difference.
posted by Mitheral at 8:26 PM on November 30, 2007 [1 favorite has favorites]

I think it's because the blue light refracts more in the lens of your eye, so it focuses in front of your retina, as if it were more distant than its surroundings. Your eye doesn't focus like a camera lens, which moves forward and back. Instead it focuses by contracting or relaxing the ciliary body muscles to make the lens thicker or thinner. When you try to focus on the blue lights, the surroundings go out of focus, making you want to re-focus, and giving you a ciliary muscle yo-yo effect. To check this out, you could squint, or look at the lights through a pinhole in a piece of dark paper. The increased depth of field should prevent you from re-focusing, and relieve the bothersome effect.
posted by weapons-grade pandemonium at 9:03 PM on November 30, 2007 [1 favorite has favorites]

Is anyone else experiencing this?

Me. The other colours aren't bad, but the blue ones hurt both my eyes and my brain. I hate them. My partner describes them as "it's like you can see them, but you can't really see them. Like they disappear if you look directly at them."
posted by arcticwoman at 10:42 PM on November 30, 2007 [1 favorite has favorites]

they don't hurt my brain, but i don't like them either. the blue and the creepy icy white ones are the worst. also: they cast no light- i put a few strings up on my porch last summer and even when they were lit, it was still too dark to eat out there. led xmas lights are sort of sneaky somehow. they're like vampire lights. stephen king sometimes writes about colours from other dimensions that hurt his characters' brains- led xmas lights do that for mine. i think they're up to no good, festive carbon reduction my ass.
posted by twistofrhyme at 12:27 AM on December 1, 2007 [4 favorites has favorites]

Blue has a highest frequency than other colours in the light spectrum. The higher frequency may cause more strain for your eyes. Red on the other hand has the lowest frequency and thus more comfortable to look at. LEDs/lights in submarines are red to keep the eyes sensitive to the dark and looking through the scope.
posted by gttommy at 12:43 AM on December 1, 2007

No pain, but I still don't like them. My blue-eyed wife is more sensitive to blue light than I am. Do you have blue eyes?
posted by BrotherCaine at 1:52 AM on December 1, 2007

A similar question was asked a few days ago. Here's my answer from that thread.

We're physiologically set up to be bad at seeing blue things in high acuity. Our eyes have three types of cones (as opposed to rods) that are used for color vision. The type of cone that maximally receives light at the short end of the spectrum is sometimes called the blue cone. These cones are a very small part of the visual system. Only five percent of the total number of cones are blue cones, and there are NO blue cones in the central two degrees of the foveal pit, where all our high acuity spatial processing takes place.

Why is this so? The standard explanation points to chromatic aberration. Different wavelengths of light get bent to different extents when passing through air, so if you try to superimpose all these differently colored images on top of one another, you'll get a blurry image. It might make sense for high spatial acuity to just rely on a small range of wavelengths in order to avoid blurriness. So, there's a possible explanation for why we use only two cones for spatial color vision. (The medium and long wavelength cones respond to light wavelengths that are very similar, so they don't produce much aberration. They are evolutionarily closely related -- one is a slight mutation of the other. The short blue cone is way down the range.)

So, don't feel bad. We're all bad at seeing blue things! I find those deep blue LEDs that suddenly appeared all over the place a few Christmases ago to be totally hypnotic for this reason. Compared to all the other colors of lights, they just look so flat.

I'd guess that you get headaches because you instinctively strain or squint to make out the blue lights in high resolution, even though you can't. Or maybe the flatness of the color just freaks you out in general. Incidentally, the night after writing that answer in the thread, I was walking through Brooklyn with some friends and came across a house sign that said "Feliz Navidad" in lights and that shifted colors. When the sign turned blue, the words became totally illegible. That was kinda neat -- I wouldn't have noticed if I hadn't just written that comment.
posted by painquale at 1:56 AM on December 1, 2007 [2 favorites has favorites]

As per the previous askme: Our eyes suck at blue. Be glad metafilter doesn't burn more.
posted by disillusioned at 1:57 AM on December 1, 2007

I was just having this discussion with my family last night. There's this mall that wraps up their hundred-ish trees with lights every year, and this year half of them switched to those horrible blue ones. I drove by the display on the highway and could not concentrate because they were so distracting.
posted by lilac girl at 10:03 AM on December 1, 2007

I haven't seen these LED lights, but the blue/violet twinkle lights have always fascinated me because (no other word for it) they tickle my eyes, and it pleases me. I see them fuzzy, but highly attractive.
posted by Goofyy at 5:10 AM on December 3, 2007