I work as a programmer this is the second year where I start to get bad eye strain and headache (together with dizziness) starting in september (this is the season where Autumn starts here). I have checked everything with my eyes and with the technical enviroment but everythings seems to be ok here. Now I come up with the idea that in september we usually start do turn on the lights and it might be correlated to this. We have Osram FH 35W/840 Cool White which has a color temperature of 4000 K. Could that be the problem? What is the right color temperature or lighting installation for this enviroment (sitting in front of a PC every day 10 hours).

  • 1
    Due to the medical/health related nature of this question, I'm not sure that it's suited to Home Improvement. Also, It's worth nothing, that looking at ANY electronic light source (your monitor) for 10 hours is going to cause eye strain and headache. It would be worth trying some good polarized screen filters AND switching to a more ambient, rather than direct lighting. I would venture a guess that it has more to do with the nature of the work (tedious and mentally taxing) AND you're looking at a monitor all day. Good luck. Sep 25, 2015 at 11:47
  • Since I haven't seen your workspace, I have to make wild guesses. But one common source of eye strain is not proper lighting around your monitor. If your monitor is very bright compared to the wall behind it, it can cause eye strain. Either lower the brightness on the monitor or add a light behind the monitor to brighten the wall.
    – diceless
    Sep 25, 2015 at 18:15

2 Answers 2


First link with an explanation about color temperature, too long to copy here: http://www.osram.nl/media/resource/hires/333565/light-can-be-white-en.pdf


  • fluorescent tubes x30 are equivalent to halogen light. I installed them in my living room because I like warm light, but warm white (2700 K) was too warm. It will not tire your eyes and won't make you feel too awake at night, so you fall asleep normally
  • tubes x40 are cheap industrial lighting, warmer than the light outside, but not so warm to make your place feel "home" (yeah this is the best I can go to be short)
  • tubes x54 are equivalent to outside light, in a bright but not sky-blue day. Not common.
  • tubes x65 are basically almost blue and equivalent to a day when the sky is without cloud, blue. Not suitable.

The "x" above can be 6, 8, 9. For industrial you use 6, better luminous efficiency, for normal use 8, for specialised work (photo editing/printing studio, expositions, ...) and 8 for the rest.

If you have 840 you should be fine, it's very common. 830 is also common, in my company this is what we use in the offices. I can clearly see that, when the light is on during the day, the office walls close to the entrance appear more reddish/yellowish than the walls closer to the window. But it doesn't matter.

Color-wise you are fine (check also the PDF linked).

If you have old ballasts, they run at 100 Hz and you may unconsciously see some flickering. Better replace them with electronic ballasts. The former produce one or two flashes when you turn the tubes on, the latter make the tubes produce at the first shot the light (do the test in the morning when the tube is cold).

If you have an electronic ballast, and you already have a tube 8(35/40/54), then the source of your eyestrain is something else.

Check the monitor, reduce sources of reflections (or of diffused glare if it is a matte display, as it should be, in general, for office work).

Check the distance between eyes and monitor: it should be at arm-length distance.

Take breaks and look around, outside the window, etc, even 10 seconds every 10 minutes help a LOT, use Workrave for Windows or AntiRSI for Mac.

  • hi! We indeed have 840, so this should not be the source of my problem. There can be so many sources (eye muscle inbalances, monitor, light...) I am at least happy I can eliminate one from the list. Thank you so much for your answer!
    – ruedi
    Sep 25, 2015 at 12:42
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    Remember however (despite the other answer about F.lux) that color temperature (of either monitor or room) should not cause eyestrain, I provided the info only to help you choose the best one for your case. I would personally focus on the head-monitor distance and on the relax of the eyes, therefore AntiRSI for Mac or WorkRave for Windows. Your neck muscles will also thank you.
    – FarO
    Sep 26, 2015 at 21:49

Where you're spending so much time at a computer, you might want to start with a relatively easy test: https://justgetflux.com/

F.lux essentially changes the colour of your display as the day goes on, adding more red the later in the day it is.

Takes a few mins to configure (basically just needs GPS coordinates), and you just keep working away.

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