Obligatory plug for an open-source alternative, Redshift:

http://jonls.dk/redshift/

I use it on my Linux boxes and it works great. There is a command line client, and a separate optional gui for control.

Android folks should check out Twilight https://play.google.com/store/apps/details?id=com.urbandroid... - note that it works by putting a colour filtered overlay on top of the existing display content. Google does block some actions while this happens - eg accepting terms/permissions for installation of an app. Consequently you have to disable twilight when doing things like app installation/updates. (flux and redshift tweak the gamma tables directly - something that isn't available on Android.)

I've been using this for about a year now. It does seem to have a noticeable impact on my comfort given the time I spend staring at screens.

The transition points at sunrise and sunset are very disruptive, however. Even knowing it is coming, it will break your thought process.

Really? I feel like mine take over an hour and I never notice them. I think that used to be a setting, but I can't seem to find it now.

(OS X, might be different on other platforms?)

Did you try adjusting your transition time? You can switch from Fast to Slow which will gradually adjust over 60 minutes. See if that works better for you.

I'll have to check, because for me its an immediate shift. It even causes system slowdown for a few seconds as it transitions.