I've now tried f.lux for the past week or so. And now I'm disabling it. I like working late at night, and being a student in a term of revising but no lectures, I'm very flexible about what times I have to wake up. So it made me tired when I didn't want to be which was annoying. It did work very well at getting me to bed though, so I'll definitely reenable it when I want to go to bed earlier.
If you have a late but fairly consistent bedtime, you can set your location several time zones to the west. f.lux kicks in at sunset in your reported location.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.