This kind of app may seem like nothing important until you actually use it. I was very skeptical about it but a few months ago I started used f.lux and it really is useful. I use my computer during the night as much I do during the day and it I noticed my eyes and my sleep was being affected. My eyes got tired very fast at night and I wasn't able to fall asleep easily. With f.lux that really changed. I urge every nocturnal computer user to give it a try!