As soon as I saw flux pop up on HN this was the first thing that came to mind. I've had trouble sleeping the past 3-4 nights and could not figure out why (no change in any other aspect of my life--diet, stress, workouts, relationships, caffeine, etc. have all been consistent). I routinely spend 2-3 hours reading, working, or watching documentaries right before I go to sleep, but this week when that time rolled around I was still wide awake for another 2-3 hours. Last night I was up until 4AM!
Sure enough, I forgot to turn F.lux back on after disabling it for some photo editing on Sunday, so while I don't have any proof this seems like a strong correlation echo'd by all of the existing research on Herf's website.