F.lux to keep me going all night long.
Without eye strain :)

I'd downloaded it for my phone, needs to be rooted.

For android I use Twilight

Yeah, I use Twilight for Android as well. It has a few minor downsides (one has to disable it for a minute when permission dialog shows in order to be able to click on any button), but it works reliably, doesn't require rooted phone and it is free.

Some monitors have this feature already, it's no flux but definitely helps if you can't install it or don't want to bother with it!

@daemon7osh They're supposed to help you with your sleep schedule!

Cf.lumen is the hand down best app in this category for Android. Everything else is a waste of battery/time.

Thanks to Chainfire.

Personally, EasyEyes is my Savior.
Also obligatory thank-you for my first >100 post

Redshift

I always use custom roms, and had this feature embedded in the os & activated since android 5