Before using f.lux fulltime I noticed that I sometimes got headaches after long days in front of displays, so I started using f.lux not only after sundown, but

Before using f.lux fulltime I noticed that I sometimes got headaches after long days in front of displays, so I started using f.lux not only after sundown, but also during the day and it's very effective. There's no way I'm going back. Essential piece of software for me.