[MattBearman]

I happened to start using f.lux on my macbook 3 days ago, and I'm loving it. Where I am (south west England) sunset is around 4pm, and I usually work until 5 or 6pm. Having a much warmer screen tone as the sky gets darker really feels nicer on my eyes.

I think you really have to use the slow transition (1 hour) mode, 20 seconds is quite jarring.

I program in Aptana with coloured text on back background, and I don't find it any harder to read in night mode. Overall, I can't recommend f.lux enough.

On a related note I've just started using http://www.protectyourvision.org to remind me to get up and move around every 20 minutes, also a highly recommended tool.