I concur - I've been using this a while and it has made a huge difference to evenings spent in front of screens, and available on all platforms.

helps if you have to drive home from the office after 12 hours, colleagues complained not being able to see other cars clearly

I tried it on Ubuntu and while it worked, it caused a lot of issue,it would cause the whole UI to go nuts, when i would close the screen (laptop) sometimes it would fuck up everything when i would re-open it, and also going 100% CPU randomly, making the computer useless.

At first i thought it was just Ubuntu not liking my graphic card, but as soon as i removed it everything went back to nomral.

f.lux is also great for short and dark winter days. I keep my day temperature around 4,400K and my night temperature around 3,400K in the winter (and substantially warmer during the summer).