I think I tried f.lux a year or so ago, and uninstalled it soon after without really giving it a shot. I wish I had stuck with it a bit more because having recently rediscovered it, I think it's making a big difference.
If you've never heard of f.lux, it is a program for OSX,
iOS, Windows & Linux that changes the overall color temperature of your display in the evening by dramatically reducing the amount of red light.
We know that night-time exposure to blue light keeps people up late. We believe that f.lux adjusts colors in a way that greatly reduces the stimulating effects of blue light at night.
When I first tried it, the red hue looked awful -- I couldn't imagine using it full time. I think my problem was I installed it at night and it immediately took out all the blue so my eyes never gradually adjusted. I'm not sure what caused me to try it again, but now I can't imagine not using it, and I wish I could actually configure my TV with the same setting when doing just casual watching.
My recommendation is to install it during the day. When it transitions to Sunset and then Bedtime it transitions gradually (you can change that if you wish). I also recommend picking custom colors and setting Sunset to about 50% and Bedtime to around 20%. The initial defaults are more extreme in the temperature adjustment and could be a bit off putting if you aren't used to it.
Unfortunately Apple won't let the app on the App Store and recently issued a cease and desist notice when they tried to distribute the source code so users could side load the app with a developer account. That just royally sucks and I'll probably have more to say on that topic later.
My one complaint is that there is a limit to the amount of customization you can do. For example, when Sunset and Bedtime occur is determined by your geo location and as far as I can tell can't be changed. I also would have liked a simple Pause/Resume control from the menu bar.
Overall however, I'm sold. f.lux has become a permanent addition to all my computers and I really hope I can get it on my iPhone & iPad soon.