Get it for free here (both Windows and mac):
justgetflux.com/
It matches the color temperature of your monitor with the temperature outside and it really lessens the strain on the eyes significantly. Sometimes I have to turn it off when I need accurate colors for photo editing, and it reminds me of how piercingly bright my screen actually is.
One of the best pieces of software I currently have installed.
Very nice! I already run my monitor on the orange side of the spectrum when I’m not doing design work, but I like the idea of it changing gradually to suit the time of day.
This is one of those programms that you get used to so fast, you forget it’s there. And then the day comes when you reboot your Mac, f.lux shuts off, and your corneas burst into flames.
I agree - it is very nice: flexible settings too. The claim is that reducing the brightness (colour) of screens when working late doesn’t affect sleep so badly. In my experience with the programme - a month or more - this does seem to be true. I go to Halogen as the evening sets in, and then to Tungsten when I know it’s my final hour (as it were).
Flaming Corneas is my favorite band.
Nice find! I like this program, thanks for bringing it to my attention, Bluesman.
Oh yeah, I love this one. And yes, whenever I have to shut f.lux off for a movie, it’s always such a shocker to see (and feel) the change–I have to grope around blindly to turn it on again post-video so I can face the screen again.
There is a sad side, though, which is that these days when it kicks into dimming at sunset, it’s not even half past four… 
somehow, it doesn’t do it for me. i keep postponing it for an hour. i also tried different configurations, i guess i need my bright screen! it’s possible that later tonight i will change my mind, but right now i keep turning it off…
EDIT: I take it back, if I use the slider and go up to 4800K (whatever that is), compared to the 3400K of halogen, it’s OK. I’ll try it for a little while. Also, I realized I was on fast transition time (20 sec), rather than the slow 1 hour transition time. That parameter may make a big difference
SECOND EDIT: I find it OK on Web pages, but not on Scrivener. I guess it’s because I customized my Scrivener background to a light grey. On Scrivener, flux doesn’t work at all for me
It’s really an eye-saver. Settings are easy and very useful to get a comfortable color temperature. A great piece of software.
Paolo
Thanks, Bluesman!
I didn’t know it. Downloaded & installed… Sounds 
good!
Giovanni
Glad you guys like it.
When I’m working on stuff really late, I use the “darkroom mode”, which makes your desktop look like the controls of a submarine. It takes a little while to get used to, but it’s even more easy on the eyes. With ALT+Pg Down and ALT+Pg Up you can quickly change the backlight, brightness as well. Very handy.
Same here. The dark days have arrived again. I truly hate this time of year. You live in England?
I have been use it for several months. Really like it.
+1 8)
I love f.lux, too, with the Tungsten setting set to fade in slowly. After many months of using it, I don’t even notice it any more, other than by its absence. I don’t know if it helps me sleep better, or if it helps my cognitive performance as a result of maintaining circadian something-or-other, but it certainly is easier on tired eyes in the evening. And I like the way it fades in in the morning as well, if I happen to have got up early.
I have f.lux set up on the user account that I use for “my” stuff, and not set up on my “work” user account, so when I pop into the virtual office in the evening, the sudden glare of bluey whiteness is always a bit of a shock to the system. I don’t know why it hasn’t occurred to me until now to set up f.lux in my work user account, too!
i’m getting used to it… on my macbook air, i seem to have to have the screen tilted at the right angle otherwise the screen seems a bit too ‘orange’… also get a bit of red blur as I scroll text… but I’m getting used to it… the difference is very noticeable when you swap back to ‘normal’ mode from using it…
I don’t get it.
The temperature outside is correlated with the ambient light in my work environment how? Are you people writing outdoors?
And doesn’t the duck/duct tape around the blinds make a perfect light seal for your writing space?
–grr
That we are not is the problem, in theory. Who knows if greatly dimming the light output of your computer monitor and keeping your office otherwise dark is necessary, or that doing the opposite and running it at daylight brightness into the night really matters—but the theory is that one’s Circadian cycle will be less confused if we do not surround ourselves with so much sunlight-white light after it has gone down. The question is whether a glowing rectangle of light being produced by a fluorescent tube or LED array is enough of a factor to be considered a zeitgeber (I think it’s pretty safe to say it is), or more importantly, if making that glowing rectangle more orange instead of white makes a difference (that is where I am dubious). Whatever the case, it sure is easier on my eyes. 8)
Rather than going to the expense and bother of ordering bifocal lenses, my brother-in-law who is an optometrist, suggested I get contact lenses of different strengths … a “near” lens for one eye, and a “far” lens for the other. I tried that … and found myself walking in wide arcs until I learned to squint the off eye.
Then he suggested that to lessen eye strain, I should have the “far” lens tinted blue for outdoor use, and the “near” lens tinted orange for indoor computer use. It works, after a fashion, but all of my photo-retouching work looks odd to my wife.
Ohhh … did I mention I got one of them new ‘touch screen’ monitors and was playing with it? My scaly old fingers tend to drag something awful on that plastic monitor surface, though. So I got a fresh frankfurter out of the fridge, and Wow … does that thing work good on the monitor. Them icons chase that hot dog around like little kittens!
Don’t forget to drape a small towel over the keyboard, though … to catch the drippin’s. :mrgreen:
Colour “temperature” refers to the tint of the ambient light around you. Bluer light (like sunlight at midday) is considered “cooler” and yellowy-red light is considered “warmer”. If you are working with any form of daylight, the colour of that light will be considered cooler than working under most artificial lights, especially incandescent globes (very yellow, more like firelight than daylight).
Note: this is a really simple description of colour temperature. However, unless you’re a photographer or artist (or live with one), this is probably all you need to know.
As for the duct tape, well yes, it seals well but unless you work in absolute darkness, you will still have ambient light and this will therefore still have a temperature colour.
There are two theories apps like f.lux are meant to address. The first is that if the colour from your monitor matches the ambient light around it, you will see the colours more accurately on the screen. However, unless you are trying to match the colour on the screen to something in the room around you, I’m not sure this is much of an issue. The second issue is that our circadian rhythm is linked to daylight. Bright sunlight does sets our circadian rhythm (it can be used to treat jet lag), so the theory is that blueish light from computers and other electronic devices mimics daylight and thus plays merry havoc with our circadian rhythm and hence our sleep (and hence our overall wellbeing). There are many psychologists and neuroscientists concerned about the effect of late night screen time on our youth (as a psychologist, so am I, but not necessarily because of the colour temperature). If this theory is correct, then apps like f.lux are supposed to stop our computers from tricking our circadian rhythm into believing it is daylight. I have not seen any evidence that it works but, just as importantly, nor have I seen any evidence that it doesn’t. It’s a cool theory (colour temperature pun not intended), but I’d like some better evidence.
Irrespective of the theoretical benefits, I’ve heard some people find it easier on their eyes (e.g. AmberV)
Personally, I tried f.lux a few years ago and stopped using it soon after I began. In short, it was fine when using the computer non-stop during the transition at dusk, but when I stopped to do something trivial (like prepare meals or spend time with family) and then return to my computer, I found the resulting sudden shift in colour to be very disconcerting. I never found the colour shift to look right and after manually turning it off each night realised I wasn’t actually using it and deleted the app. Maybe it’s better now and I should revisit it…