One of the Android apps I use most often – to be fair, that’s because you set it up once and leave it alone – is Twilight. It’s basically f.lux for Android. Technically f.lux for Android is f.lux for Android, but it only works for some phones and requires root.
f.lux (and Twilight) if you haven’t already heard of it, automatically changes the colour balance of your screen to a warmer, more restful shade when the sun goes down. It’s supposed to help you sleep, which I honestly couldn’t say if it actually does, but I personally like it because it feels more restful to my eyes.
That’s great if you’re running Android, Windows, or Mac, but what if you have an iOS device? Well, if you’re willing to jailbreak it you can get f.lux, but if you can’t or don’t want to, you can use this trick to dim your screen. It’s not the same, but it’s certainly better than nothing.
One last thing to note: because Twilight is a screen overlay, Android won’t let you install anything while it’s running, even if it’s not currently changing the colour of your screen. That totally makes sense from a security standpoint, but I wish it would display an error message instead of just silently refusing to do as it’s told. If, for example, you happened to spend an afternoon cursing at your phone because it mysteriously refused to let you install a test build so you could do some debugging, that would be why. Turn off Twilight and magically things will start working again :)