Isn't this a perfect example where using more than localtime() is pointless? Just because it's dark all the time outside you don't want your screen to be red-ish all the time. And in summer you want the effect if you try to sleep, even if the sun is still relatively high.
I generally have a hard time getting to sleep, and most mornings feel like I've been run over by a steamroller, so I don't mind a little red tint if it makes even a tiny difference in the quality of my sleep.
[0] https://en.wikipedia.org/wiki/Delayed_sleep_phase_disorder
I can understand wanting the screen to tint reddish when it's 9 or 10 pm, because I should be going to bed soon.
I don't necessarily want it changing colors at 4pm when it starts getting dark here in the winter. At 4:00, I still need to be up for another 6-10 hours.
Solar noon details here: http://blog.poormansmath.net/images/SolarTimeVsStandardTimeV...